Federal tax engine: sources

IRS underpayment rate by quarter

Used by: Extended fields: Schedule A, 8606, 5329, the RMD, blindness, QSS and Form 2210; Form 2210: the penalty. Status: verified.

• Quarterly interest rates (Internal Revenue Service; record) checked 2026-10-12
  Underpayment (corporate and non-corporate) 7% 7% 6% 7%; 4th quarter rates - Internal Revenue Bulletin: 2026-36

Rev. Rul. numbers 2025-7/-11/-18/-22, 2026-5/-10/-15 each confirmed in IRB 2025-13/23/37/48, 2026-08/22/36.

Tax-exempt interest (§103) enters Social Security provisional income (§86(b)(2)(B)) but not taxable income

Used by: Tax-exempt interest. Status: verified.

• 26 U.S. Code § 103 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income does not include interest on any State or local bond
• 26 U.S. Code § 86 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the amount of interest received or accrued by the taxpayer during the taxable year which is exempt from tax

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

Form 1040 and schedules: the line each engine value is reported on (TY2025 forms; the TY2026 forms are not yet published)

Used by: Tax-exempt interest; IRA distributions and Roth conversions; Pensions and annuities; Social Security benefits; Taxable Social Security (the Pub 915 worksheet); Net short-term gain or loss; Net long-term gain or loss; Combined net gain or loss; Line 7a: the net gain, or a net loss; Other ordinary income; Total income; Adjusted gross income; Standard deduction and the §63(f) aged amount; The senior deduction (Schedule 1-A); Additional deductions on line 13b; Total deductions; Taxable income; Tax: the brackets and the capital-gains worksheet; Tax: the Tax Table below $100,000; Tax: the Schedule D Tax Worksheet; The 10% additional tax on early distributions; Net investment income tax; Other taxes; Total tax. Status: verified.

• Form 1040 (2025): U.S. Individual Income Tax Return (Internal Revenue Service; record) checked 2026-10-12
  Tax-exempt interest; IRA distributions; Pensions and annuities; Social security benefits; Capital gain or (loss). Attach Schedule D if required; Additional income from Schedule 1, line 10; This is your total income; This is your adjusted gross income; Standard deduction or itemized deductions (from Schedule A); Additional deductions from Schedule 1-A, line 38; Add lines 12e, 13a, and 13b; This is your taxable income; Tax (see instructions); Other taxes, including self-employment tax, from Schedule 2, line 21; This is your total tax
• Schedule 1-A (Form 1040) (2025): Additional Deductions (Internal Revenue Service; record) checked 2026-10-12
  Enhanced deduction for seniors. Add lines 36a and 36b
• Schedule 2 (Form 1040) (2025): Additional Taxes (Internal Revenue Service; record) checked 2026-10-12
  Additional tax on IRAs or other tax-favored accounts; Net investment income tax. Attach Form 8960; These are your total other taxes
• Schedule D (Form 1040) (2025): Capital Gains and Losses (Internal Revenue Service; record) checked 2026-10-12
  Net short-term capital gain or (loss); Net long-term capital gain or (loss); Combine lines 7 and 15 and enter the result

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

IRA distributions are included in gross income (§408(d)(1))

Used by: IRA distributions and Roth conversions. Status: verified.

• 26 U.S. Code § 408 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  any amount paid or distributed out of an individual retirement plan shall be included in gross income by the payee or distributee

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

Pension and annuity payments are included in gross income (§72(a))

Used by: Pensions and annuities. Status: verified.

• 26 U.S. Code § 72 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income includes any amount received as an annuity

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

SS taxability base / adjusted base §86(c)

Used by: Social Security benefits; Taxable Social Security (the Pub 915 worksheet). Status: verified.

• 26 U.S. Code § 86 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  (A) except as otherwise provided in this paragraph, $25,000, (B) $32,000 in the case of a joint return, and (C) zero; (A) except as otherwise provided in this paragraph, $34,000, (B) $44,000 in the case of a joint return

Pub 915 MFS lived-apart uses $25,000

Used by: Taxable Social Security (the Pub 915 worksheet). Status: verified.

• Publication 915, Social Security and Equivalent Railroad Retirement Benefits (Internal Revenue Service; record) checked 2026-10-12
  $25,000 if you are married filing separately and lived apart from your spouse for all of; $0 if you are married filing separately and lived with your spouse at any time during

Pub 915 currently shows the 2025 edition (same statutory amounts).

Net short-term, net long-term and net capital gain (§1222)

Used by: Net short-term gain or loss; Net long-term gain or loss; Combined net gain or loss. Status: verified.

• 26 U.S. Code § 1222 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the excess of short-term capital gains for the taxable year over the short-term capital losses for such year; the excess of long-term capital gains for the taxable year over the long-term capital losses for such year; the excess of the gains from sales or exchanges of capital assets over the losses from such sales or exchanges

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

Capital-gain distributions: 1099-DIV box 2a -> Form 1040 line 7a (Schedule D not required box, line 7b) or Schedule D line 13; QDCG worksheet line 3

Used by: Capital-gain distributions (Schedule D line 13). Status: verified.

• Instructions for Form 1040 (2025), line 7a/7b and QDCG worksheet (Internal Revenue Service; record) checked 2026-10-12
  your only capital gains are capital gain distributions from form(s) 1099-div, box 2a (or substitute statements); none of the form(s) 1099-div (or substitute statements) have an amount in box 2b (unrecaptured section 1250 gain), box 2c (section 1202 gain), or box 2d (collectibles (28%) gain); if exception 1 applies, enter your total capital gain distributions (from box 2a of form(s) 1099-div) on line 7a and check the box "schedule d not required" on line 7b; use the qualified dividends and capital gain tax worksheet in the line 16 instructions to figure your tax; no. enter the amount from form 1040 or 1040-sr, line 7a
• Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  capital gain or (loss). attach schedule d if required; schedule d not required
• Form 1040 (2026) DRAFT - do not file (Internal Revenue Service; record) checked 2026-10-12
  form 1040 (2026) created 8/19/26 draft - do not file; capital gain or (loss). attach schedule d if required . . . . . . . . . check if: schedule d not required
• Instructions for Schedule D (2025), capital gain distributions (Internal Revenue Service; record) checked 2026-10-12
  enter on schedule d, line 13, the total capital gain distributions paid to you during the year, regardless of how long you held your investment. this amount is shown in box 2a of form 1099-div; if there is an amount in box 2b, include that amount on line 11 of the unrecaptured section 1250 gain worksheet in these instructions if you complete line 19 of schedule d; if there is an amount in box 2d, include that amount on line 4 of the 28% rate gain worksheet in these instructions if you complete line 18 of schedule d
• Publication 550 (2025), Investment Income and Expenses (Internal Revenue Service; record) checked 2026-10-12
  capital gain distributions (capital gain dividends) are paid to you or credited to your account by mutual funds (or other regulated investment companies) and real estate investment trusts (reits); report capital gain distributions as long-term capital gains, regardless of how long you owned your shares in the mutual fund or reit; capital gain distributions line 7a, or, if required, schedule d, line 13
• Form 1099-DIV (Rev. January 2024) (Internal Revenue Service; record) checked 2026-10-12
  2a total capital gain distr. 2b unrecap. sec. 1250 gain; 2c section 1202 gain 2d collectibles (28%) gain
• Instructions for Form 1099-DIV (payer) (Internal Revenue Service; record) checked 2026-10-12
  enter any amount included in box 2a that is an unrecaptured section 1250 gain from certain depreciable real property; enter any amount included in box 2a that is a section 1202 gain from certain qualified small business stock

Qualified dividends as net capital gain (§1(h)(11)) are already verified in rule qualified_dividends; not repeated. A box-2b/2c/2d amount forces Schedule D and, when line 18 or 19 of Schedule D is non-zero, the Schedule D Tax Worksheet (rule cg_28_1250_rates). Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

28% rate gain and unrecaptured §1250 gain: §1(h)(1)(E)/(F), §1(h)(3)-(4); Schedule D lines 18-20 route to the Schedule D Tax Worksheet

Used by: 28% rate gain (Schedule D line 18); Unrecaptured section 1250 gain (Schedule D line 19); Tax: the Schedule D Tax Worksheet. Status: verified.

• 26 U.S. Code §1(h) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  (e) 25 percent of the excess (if any) of- (i) the unrecaptured section 1250 gain (or, if less, the net capital gain (determined without regard to paragraph (11))), over; (f) 28 percent of the amount of taxable income in excess of the sum of the amounts on which tax is determined under the preceding subparagraphs of this paragraph; reduced (but not below zero) by the sum of- (i) unrecaptured section 1250 gain, and (ii) 28-percent rate gain, plus (b) qualified dividend income; the term "28-percent rate gain" means the excess (if any) of- (a) the sum of- (i) collectibles gain; and (ii) section 1202 gain
• Schedule D (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  if you are required to complete the 28% rate gain worksheet (see instructions), enter the amount, if any, from line 7 of that worksheet; if you are required to complete the unrecaptured section 1250 gain worksheet (see instructions), enter the amount, if any, from line 18 of that worksheet; complete the qualified dividends and capital gain tax worksheet in the instructions for form 1040, line 16. don't complete lines 21 and 22 below. no. complete the schedule d tax worksheet in the instructions
• Instructions for Schedule D (2025), Schedule D Tax Worksheet (Internal Revenue Service; record) checked 2026-10-12
  complete this worksheet only if line 18 or line 19 of schedule d is more than zero and lines 15 and 16 of schedule d are gains; multiply line 39 by 25% (0.25); multiply line 42 by 28% (0.28); unrecaptured section 1250 gain. subtract line 17 from line 13. if zero or less, enter -0-. if more than zero, enter the result here and on schedule d, line 19
• Schedule D (Form 1040) 2026 DRAFT (Internal Revenue Service; record) checked 2026-10-12
  schedule d (form 1040) 2026

TY2026 Schedule D instructions draft on irs-dft is still the TY2025 text (mentions carryover from 2024 to 2025); use final TY2025 instructions for the worksheet structure. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

§1211(b) capital loss limit

Used by: Line 7a: the net gain, or a net loss; Capital loss allowed (Schedule D line 21). Status: verified.

• 26 U.S. Code § 1211 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the lower of- (1) $3,000 ($1,500 in the case of a married individual filing a separate return)

fed2/w3a (R2) added the limit behind an opt-in; engine 1.3.0 (fed2/r13) applies it on every return, the planner's default path and POST /api/federal-tax included. FedInputExt.capital_loss_floor (API capitalLossRules:false) is the explicit opt-out to the pre-1.3.0 floor (a net loss is a zero gain).

Gross income (§61)

Used by: Other ordinary income; Total income. Status: verified.

• 26 U.S. Code § 61 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income means all income from whatever source derived

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

§469 passive activity loss limit and the $25,000 offset for rental real estate with active participation

Used by: Rental real estate: the passive activity loss limit (Form 8582); Partnerships, S corporations, estates and trusts (Schedule E Parts II-III) and Form 8582's other passive activities. Status: verified.

• 26 U.S. Code § 469 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Except as provided in paragraph (7), the term "passive activity" includes any rental activity.; The aggregate amount to which paragraph (1) applies for any taxable year shall not exceed $25,000.; the $25,000 amount under paragraph (2) shall be reduced (but not below zero) by 50 percent of the amount by which the adjusted gross income of the taxpayer for the taxable year exceeds $100,000; (i) any amount includible in gross income under section 86,; (iii) the amounts allowable as a deduction under sections 219, 221, and 250, and (iv) any passive activity loss or any loss allowable by reason of subsection (c)(7); (i) "$12,500" for "$25,000" each place it appears, (ii) "$50,000" for "$100,000" in paragraph (3)(A); does not live apart from his spouse at all times during such taxable year; such interest (including any interest of the spouse of the individual) is less than 10 percent (by value) of all interests in such activity; paragraph (2) shall not apply to any rental real estate activity of such taxpayer for such taxable year; such taxpayer performs more than 750 hours of services during the taxable year in real property trades or businesses in which the taxpayer materially participates; any unused deduction allocable to such activity under subsection (b) shall be offset against the income from such activity for the taxable year; any such deduction or credit remaining after the application of subparagraphs (A) and (B) shall continue to be treated as arising from a passive activity; any loss or credit from an activity which is disallowed under subsection (a) shall be treated as a deduction or credit allocable to such activity in the next taxable year

Added 2026-10-06 (fed/2.1, engine 2.1.0); every quote checked with scripts/check_state_tax_sources.py. §469(i)(3)(E) lists the MAGI exclusions in the statute (§86 social security, §§219/221/250 deductions, passive losses); the Form 8582 instructions (rule form_8582) also leave out the deductible part of self-employment tax, and the engine follows the instructions. §469(i)(1)-(3) amounts are fixed in law (no inflation clause): rule fed-pal-allowance of research/data/federal-tax-indexing.json. §469(c)(7)(B) tests (more than half of personal services, more than 750 hours, material participation) are the caller's assertion (realEstateProfessional). §469(f)(1)(C): a prior unallowed loss of a former passive activity left after offsetting that activity's income stays passive: it goes on Form 8582 and can use the special allowance (rule form_8582).

Form 8582 (2025) Parts I-III: the rental real estate special allowance

Used by: Rental real estate: the passive activity loss limit (Form 8582). Status: verified.

• Form 8582 (2025), Passive Activity Loss Limitations (Internal Revenue Service; record) checked 2026-10-12
  Prior years' unallowed losses (enter the amount from Part IV, column (c)); Combine lines 1a, 1b, and 1c; If this line is zero or more, stop here and include this form with your return; all losses are allowed, including any prior year unallowed losses entered on line 1c or 2c.; If your filing status is married filing separately and you lived with your spouse at any time during the year, do not complete Part II. Instead, go to line 10.; Enter the smaller of the loss on line 1d or the loss on line 3; Enter $150,000. If married filing separately, see instructions; Enter modified adjusted gross income, but not less than zero. See instructions; Multiply line 7 by 50% (0.50). Do not enter more than $25,000. If married filing separately, see instructions; Add the income, if any, on lines 1a and 2a and enter the total; Total losses allowed from all passive activities for 2025. Add lines 9 and 10.
• Instructions for Form 8582 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Married persons filing separate returns who lived apart from their spouses at all times during the year must enter $75,000 on line 5 instead of $150,000.; To figure modified adjusted gross income, combine all the amounts used to figure adjusted gross income, except don't take into account:; Any passive activity loss as defined in section 469(d) (1),; Any rental real estate loss allowed to real estate professionals; The taxable amount of social security and tier 1 railroad retirement benefits,; Deductible contributions to traditional individual retirement accounts (IRAs) and section 501(c)(18) pension plans,; The deduction allowed for the deductible part of self-employment taxes,; The student loan interest deduction, or; Don't enter more than $12,500 on line 8 if you're married filing a separate return and you and your spouse lived apart at all times during the year.; The special allowance isn't available if you were married, are filing a separate return for the year, and lived with your spouse at any time during the year.; Your adjusted gross income on line 11 of Form 1040 or Form 1040-SR is $92,000 and you have taxable social security benefits of $5,500 on line 6b. Your modified adjusted gross income is $86,500 ($92,000 - $5,500).; PALs not allowed in the current year are carried forward until they're allowed either against passive activity income; against the special allowance, if applicable;; If a rental real estate activity isn't a passive activity for the current year, any prior-year unallowed loss is treated as a loss from a former passive activity.; A prior-year unallowed loss from a former passive activity is allowed to the extent of current year income from the activity.; If current year net income from the activity is more than the prior-year unallowed loss from the activity, enter the prior-year unallowed loss and the current year net income up to the amount of prior-year unallowed loss on Form 8582.; If the activity has a net loss for the current year, enter the prior-year unallowed loss (but not the current year loss) on Form 8582.

Added 2026-10-06 (fed/2.1, engine 2.1.0). One rental net amount per return (Schedule E line 21 total): Part I line 1a (income) or 1b (loss), the prior unallowed loss on line 1c; without active participation the same amounts go on line 2a-2c and Part II does not apply (line 3 < 0 and line 1d >= 0 skips to line 10). Line 6 MAGI items the engine has: the rental activity itself (a passive loss is left out), taxable social security, the IRA deduction, the deductible part of SE tax, the student loan interest deduction. The series EE/I bond and adoption-assistance exclusions and the FDII/GILTI deduction are not in the engine. Correction to the 2.1 design (real estate professional with a prior unallowed loss): the prior-year loss of the former passive activity goes on Form 8582 with the current net income up to that loss (none when the year is a loss; the current-year loss itself is nonpassive and allowed in full). So the prior loss is allowed against that income AND, the activity being rental real estate with active participation, the rest can still use the Part II special allowance; only what is left after Part II carries forward. Line 6 MAGI leaves out the professional's nonpassive rental loss (§469(i)(3)(E)(iv)).

Schedule E (2025) Part I totals: rental real estate income or loss to Schedule 1 line 5; rents are net investment income and not self-employment income

Used by: Rental real estate income or loss (Schedule E line 26, Schedule 1 line 5); Net investment income: rents (Form 8960 line 4a). Status: verified.

• Schedule E (Form 1040) 2025, Supplemental Income and Loss (Internal Revenue Service; record) checked 2026-10-12
  Subtract line 20 from line 3 (rents) and/or 4 (royalties).; Deductible rental real estate loss after limitation, if any, on Form 8582 (see instructions); Income. Add positive amounts shown on line 21. Do not include any losses; Losses. Add royalty losses from line 21 and rental real estate losses from line 22. Enter total losses here; Total rental real estate and royalty income or (loss). Combine lines 24 and 25. Enter the result here. If Parts II, III, and IV, and line 40 on page 2 do not apply to you, also enter this amount on Schedule 1 (Form 1040), line 5. Otherwise, include this amount in the total on line 41 on page 2; Total income or (loss). Combine lines 26, 32, 37, 39, and 40. Enter the result here and on Schedule 1 (Form 1040), line 5
• Instructions for Schedule E (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  You may need to complete Form 8582 to figure the amount of loss, if any, to enter on line 22.; If you have an unallowed rental real estate loss from a prior year that after completing Form 8582 you can include this year, include that loss on line 22.
• Form 8960 (2025), Net Investment Income Tax (Internal Revenue Service; record) checked 2026-10-12
  Rental real estate, royalties, partnerships, S corporations, trusts, trades or businesses, etc. (see instructions)
• Instructions for Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Line 4a of Form 8960 includes total income reported on Schedules C, E, and F (Form 1040) that is potentially subject to NIIT.; Schedule 1 (Form 1040), line 5.; Conversely, a total loss comprised of both passive and nonpassive income is entered as a negative on line 4a.
• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income from interest, dividends, annuities, royalties, and rents
• 26 U.S. Code § 1402 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  there shall be excluded rentals from real estate and from personal property leased with the real estate

Added 2026-10-06 (fed/2.1, engine 2.1.0). Not modelled (disclosed): the Rev. Proc. 2019-38 QBI safe harbour for rental real estate, the §1.1411-4(g)(7) rule that takes a qualifying real estate professional's rental income out of net investment income, §469(g) dispositions and the per-activity allocation of an unallowed loss (Form 8582 worksheets 5-6).

Wages: Form 1040 line 1a (W-2 box 1); line 1z total

Used by: Wages (Form 1040 line 1a). Status: verified.

• Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  total amount from form(s) w-2, box 1 (see instructions)
• Form 1040 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  total amount from form(s) w-2, box 1 (see instructions); add lines 1a through 1h

FICA rates 6.2%/1.45% and the $184,500 2026 wage base are verified in rules fica_rates, ss_wage_base, ss_wage_base_fr. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

FICA rates / Additional Medicare

Used by: Wages (Form 1040 line 1a); Self-employment tax (Schedule SE, Schedule 2 line 4); Additional Medicare Tax (Form 8959); Employee payroll taxes (FICA), a standalone function. Status: verified.

• 26 U.S. Code § 3101 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  a tax equal to 6.2 percent of the wages; a tax equal to 1.45 percent of the wages; a tax equal to 0.9 percent of wages; in the case of a joint return, $250,000; in any other case, $200,000

SE factor 0.9235 derived from §1402(a)(12) (1 - half of 15.3%).

Self-employment tax: Schedule SE 92.35% (line 4a), $400 floor (§1402(b)(2)), 12.4% up to wage base less SS wages (lines 7-10), 2.9% (line 11), half deductible (§164(f), line 13 -> Schedule 1 line 15), SE tax -> Schedule 2 line 4

Used by: Business income (Schedule 1 line 3); Self-employment tax (Schedule SE, Schedule 2 line 4); Deductible part of self-employment tax (Schedule 1 line 15); Adjustments to income (Form 1040 line 10). Status: verified.

• 26 U.S. Code §1401(a)-(b)(1) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  a tax equal to 12.4 percent of the amount of the self-employment income for such taxable year; a tax equal to 2.9 percent of the amount of the self-employment income for such taxable year
• 26 U.S. Code §1402 (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  the net earnings from self-employment, if such net earnings for the taxable year are less than $400; that part of the net earnings from self-employment which is in excess of (i) an amount equal to the contribution and benefit base (as determined under section 230 of the social security act) which is effective for the calendar year in which such taxable year begins, minus (ii) the amount of the wages paid to such individual during such taxable years; one-half of the sum of the rates imposed by subsections (a) and (b) of section 1401 for such year (determined without regard to the rate imposed under paragraph (2) of section 1401(b))
• 26 U.S. Code §164(f) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  there shall be allowed as a deduction for the taxable year an amount equal to one-half of the taxes imposed by section 1401 (other than the taxes imposed by section 1401(b)(2)) for such taxable year
• Schedule SE (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  if line 3 is more than zero, multiply line 3 by 92.35% (0.9235); combine lines 4a and 4b. if less than $400, stop; you don't owe self-employment tax; subtract line 8d from line 7. if zero or less, enter -0- here and on line 10 and go to line 11; multiply the smaller of line 6 or line 9 by 12.4% (0.124); multiply line 6 by 2.9% (0.029); enter here and on schedule 2 (form 1040), line 4; deduction for one-half of self-employment tax. multiply line 12 by 50% (0.50). enter here and on schedule 1 (form 1040), line 15
• Schedule SE (Form 1040) 2026 DRAFT (Internal Revenue Service; record) checked 2026-10-12
  maximum amount of combined wages and self-employment earnings subject to social security tax or $184,500 the 6.2% portion of the 7.65% railroad retirement (tier 1) tax for 2026
• Instructions for Form 1040 (2025), Schedule 1 line 15 (Internal Revenue Service; record) checked 2026-10-12
  line 15 deductible part of self-employment tax if you were self-employed and owe self-employment tax, fill in schedule se to figure the amount of your deduction

The 0.9% Additional Medicare on SE income is excluded from the half-SE-tax deduction (§164(f)(1) parenthetical) - see rule addl_medicare_8959 for 8959 Part II. TY2026 draft Schedule SE instructions (irs-dft/i1040sse--dft.pdf) are TY2026 text. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

QBI deduction, simplified (Form 8995): 20% of QBI, limited to 20% of (taxable income before QBI minus net capital gain incl. qualified dividends); QBI reduced by deductible half of SE tax, SE health insurance and retirement contributions

Used by: Business income (Schedule 1 line 3); Self-employed retirement plan deduction (Schedule 1 line 16); Self-employed health insurance deduction (Schedule 1 line 17); Adjustments to income (Form 1040 line 10); Qualified business income deduction (Forms 8995 / 8995-A). Status: verified.

• 26 U.S. Code §199A(a) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  an amount equal to 20 percent of the excess (if any) of- (a) the taxable income of the taxpayer for the taxable year, over (b) the net capital gain (as defined in section 1(h)) of the taxpayer for such taxable year; 20 percent of the taxpayer's qualified business income with respect to the qualified trade or business
• Instructions for Form 8995 (2025) (Internal Revenue Service; record) checked 2026-10-12
  this includes, but isn't limited to, unreimbursed partnership expenses, business interest expense, deductible part of self-employment tax, self-employment health insurance deduction, and contributions to qualified retirement plans
• Form 8995 (2025) (Internal Revenue Service; record) checked 2026-10-12
  use this form if your taxable income, before your qualified business income deduction, is at or below $197,300 ($394,600 if married filing jointly)
• Form 8995 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  use this form if your taxable income, before your qualified business income deduction, is at or below $201,750 ($201,775 if married filing separately; $403,500 if married filing jointly); qualified business income component. multiply line 4 by 20% (0.20); enter your net capital gain, if any, increased by any qualified dividends; income limitation. multiply line 13 by 20% (0.20); minimum deduction for active qualified business income (see instructions); qualified business income deduction. enter the greater of line 15 or line 16
• Form 1040 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  qualified business income deduction from form 8995 or form 8995-a

Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

OASDI wage base 2026

Used by: Self-employment tax (Schedule SE, Schedule 2 line 4); Excess social security tax withheld (Schedule 3 line 11); Employee payroll taxes (FICA), a standalone function. Status: verified.

• Contribution and benefit base (Social Security Administration, Office of the Chief Actuary; record) checked 2026-10-12
  For earnings in 2026, this base is $184,500; The OASDI tax rate for self-employment income in 2026 is 12.4 percent

Additional Medicare Tax 0.9%: §3101(b)(2) wages, §1401(b)(2) SE income with the wage coordination; Form 8959 -> Schedule 2 line 11

Used by: Additional Medicare Tax (Form 8959); Employee payroll taxes (FICA), a standalone function. Status: verified.

• 26 U.S. Code §1401 (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  a tax equal to 0.9 percent of the self-employment income for such taxable year which is in excess of- (i) in the case of a joint return, $250,000; the amounts under clause (i), (ii), or (iii) (whichever is applicable) of subparagraph (a) shall be reduced (but not below zero) by the amount of wages taken into account in determining the tax imposed under section 3121(b)(2) with respect to the taxpayer
• Form 8959 (2025) (Internal Revenue Service; record) checked 2026-10-12
  also include this amount on schedule 2 (form 1040), line 11; self-employment income from schedule se (form 1040), part i, line 6. if you had a loss, enter -0-; married filing jointly . . . . . . . . . . . . . . . $250,000 married filing separately . . . . . . . . . . . . . . $125,000 single, head of household, or qualifying surviving spouse . . . $200,000
• Instructions for Form 8959 (2025) (Internal Revenue Service; record) checked 2026-10-12
  medicare wages and self-employment income are combined to determine if your income exceeds the threshold. a self-employment loss shouldn't be considered for purposes of this tax; the $130,000 of kathleen's wages reduces liam's self-employment income threshold to $120,000 ($250,000 threshold minus the $130,000 of wages, as figured on lines 9 through 11 of form 8959)
• Instructions for Form 8959 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  filing status threshold amount married filing jointly $250,000 married filing separately $125,000 single $200,000 head of household $200,000 qualifying surviving spouse $200,000
• Schedule 2 (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  11 additional medicare tax. attach form 8959

Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Excess social security withheld with more than one employer: §6413(c)(1) + §31(b); Schedule 3 line 11

Used by: Excess social security tax withheld (Schedule 3 line 11). Status: verified.

• 26 U.S. Code §6413(c) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  if by reason of an employee receiving wages from more than one employer during a calendar year the wages received by him during such year exceed the contribution and benefit base
• 26 U.S. Code §31(b) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  the amount allowed as a credit under such regulations shall, for purposes of this subtitle, be considered an amount withheld at source as tax under section 3402
• Instructions for Form 1040 (2025), Schedule 3 line 11 (Internal Revenue Service; record) checked 2026-10-12
  line 11 excess social security and tier 1 rrta tax withheld if you, or your spouse if filing a joint return, had more than one employer for 2025 and total wages of more than $176,100; you can take a credit on this line for the amount withheld in excess of $10,918.20. but if any one employer withheld more than $10,918.20, you can't claim the excess on your return; figure this amount separately for you and your spouse
• Schedule 3 (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  excess social security and tier 1 rrta tax withheld

The 2026 cap (6.2% x $184,500) is arithmetic, not a quoted figure; no final TY2026 instruction text states it yet (the i1040gi draft on irs-dft is still TY2025). Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Social Security retirement earnings test: exempt amounts, $1-for-$2 / $1-for-$3 withholding, which earnings count (42 U.S.C. 403(f))

Used by: The Social Security earnings test, a standalone function. Status: verified.

• SSA OACT: Exempt amounts under the earnings test (Social Security Administration; record) checked 2026-10-12
  we withhold $1 in benefits for every $2 of earnings in excess of the lower exempt amount; we withhold $1 in benefits for every $3 of earnings in excess of the higher exempt amount; these exempt amounts generally increase annually with increases in the national average wage index; this higher exempt amount applies only to earnings made in months prior to the month of nra attainment
• SSA: Receiving Benefits While Working (Social Security Administration; record) checked 2026-10-12
  we count only the wages you make from your job or your net profit if you're self-employed; we don't count pensions, annuities, investment income, interest, veterans benefits, or other government or military retirement benefits; for 2026, that limit is $24,480; in 2026, this limit on your earnings is $65,160
• 42 U.S. Code §403(f) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  an individual's excess earnings for a taxable year shall be 33⅓ percent of his earnings for such year in excess of the product of the applicable exempt amount; or 50 percent of his earnings for such year in excess of such product in the case of any other individual; an individual's earnings for a taxable year shall be (i) the sum of his wages for services rendered in such year and his net earnings from self-employment for such year, minus (ii) any net loss from self-employment for such year

20 CFR 404.430/404.434 on eCFR render their body text client-side; a plain fetch returned only page chrome, so no claim is recorded there (status unverifiable). 42 U.S.C. 403(f) is used instead. Exempt amounts are set as MONTHLY amounts rounded to $10 (403(f)(8)(B)); the annual figures are 12x. 20 CFR 404.430 (eCFR) is not cited: eCFR renders the section text in the browser, so the weekly checker's fetch returns only page chrome and the quote cannot be verified (federal engine 2.0 W0, 2026-09-30). 42 U.S.C. 403(f) carries the same rule and is cited instead. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Retirement earnings test 2026

Used by: The Social Security earnings test, a standalone function. Status: verified.

• Exempt amounts under the earnings test (Social Security Administration, Office of the Chief Actuary; record) checked 2026-10-12
  the annual exempt amount in 2026 is $24,480; For people attaining NRA in 2026, the annual exempt amount is $65,160

Adjusted gross income (§62)

Used by: Adjusted gross income. Status: verified.

• 26 U.S. Code § 62 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  in the case of an individual, gross income minus the following deductions

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

2026 standard deduction

Used by: Standard deduction and the §63(f) aged amount; The year's brackets and deductions. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Married Individuals Filing Joint Returns and Surviving Spouses (§ 1(j)(2)(A)) $32,200 Heads of Households (§ 1(j)(2)(B)) $24,150; (§ 1(j)(2)(C)) $16,100 Married Individuals Filing Separate Returns (§ 1(j)(2)(D)) $16,100

Rev. Proc. 2025-32 §4.14(1).

§63(f) additional std deduction aged/blind 2026

Used by: Standard deduction and the §63(f) aged amount; The year's brackets and deductions. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  the additional standard deduction amount under § 63(f) for the aged or the blind is $1,650. The additional standard deduction amount is increased to $2,050 if the individual is also unmarried and not a surviving spouse

Rev. Proc. 2025-32 §4.14(3) (section 4 holds the 2026 items). Code comments and the standard-deduction pages cited the 2025 section (3); corrected 2026-09-28. Engine 1.5.0: a filer or spouse born on January 1 takes it a year early (rule age65_day_before).

Age 65 is reached the day before the 65th birthday (born January 1 = 65 at the end of the prior year)

Used by: Standard deduction and the §63(f) aged amount; The senior deduction (Schedule 1-A). Status: verified.

• Publication 554 (2025), Tax Guide for Seniors (Internal Revenue Service; record) checked 2026-10-12
  You are considered age 65 on the day before
• Instructions for Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  If you were born on January 1, 1961, you are considered to be age 65 at the end of 2025; A person is considered to reach age 65 on the day before the person's 65th birthday
• Schedule 1-A (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  were born before January 2, 1961

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect. Applied to the two age-65 tests only: the RMD applicable age reads the date of birth (26 CFR 1.401(a)(9)-2), and no IRS text applies the day-before rule to 55, 59½ or 70½.

§63(f)(2) additional standard deduction for the blind

Used by: Additional standard deduction for blindness. Status: verified.

• 26 U.S. Code § 63 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  (2) Additional amount for blindThe taxpayer shall be entitled to an additional amount of $600- (A) for himself if he is blind at the close of the taxable year
• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  the additional standard deduction amount under § 63(f) for the aged or the blind is $1,650. The additional standard deduction amount is increased to $2,050 if the individual is also unmarried and not a surviving spouse

The MFS case of a spouse with no income who is not a dependent (§63(f)(2)(B) via §151(b)) is not modelled: MFS counts the filer only.

Line labels of Schedule A, Forms 8606, 5329 and 2210 (TY2025 forms; TY2026 not yet published)

Used by: Additional standard deduction for blindness; Medical and dental expenses; State and local taxes paid; The SALT cap and its phase-down; Interest you paid; Gifts to charity: the percentage limits and the 0.5% floor; Total itemized deductions; Form 8606: the nontaxable part of a conversion; Form 8606: the nontaxable part of all distributions; Form 8606: basis carried forward; Roth IRA distributions: ordering and the 5-year rules; Form 5329: early distributions; Form 5329: the exceptions to the additional tax; Form 5329: the missed-RMD excise tax; Form 2210: the required annual payment; Form 2210: the underpayment by installment; Form 2210: the penalty. Status: verified.

• Schedule A (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  Subtract line 3 from line 1. If line 3 is more than line 1, enter -0-; Add lines 5a through 5c; Enter the smaller of line 5d or $40,000 ($20,000 if married filing separately); Add lines 8e and 9; Add lines 11 through 13; Add the amounts in the far right column for lines 4 through 16
• Form 8606 (2025) (Internal Revenue Service; record) checked 2026-10-12
  This is the nontaxable portion of the amount you converted to Roth IRAs; Add lines 11 and 12. This is the nontaxable portion of all your distributions; c Taxable amount. Subtract line 25b from line 25a; Subtract line 13 from line 3. This is your total basis in traditional IRAs for 2025 and earlier years
• Form 5329 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Early distributions included on line 1 that are not subject to the additional tax; 55 Add lines 54a and 54b. Include the total on Schedule 2 (Form 1040), line 8
• Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Required annual payment. Enter the smaller of line 5 or line 8; 19 Penalty. Enter the total penalty from line 14 of the Worksheet for Form 2210, Part III, Section B-Figure the Penalty; Required installments. If box C in Part II applies

The engine's own ids for amounts the TY2025 forms have no line for (the §68 reduction, the blind addition, the itemize flag, the §170(p) deduction, the RMD) say so in their labels.

OBBBA senior deduction §151(d)(5)(C)

Used by: The senior deduction (Schedule 1-A); The year's brackets and deductions. Status: verified.

• 26 U.S. Code § 151 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  In the case of a taxable year beginning before January 1, 2029, there shall be allowed a deduction in an amount equal to $6,000 for each qualified individual; reduced (but not below zero) by 6 percent of so much of the taxpayer's modified adjusted gross income as exceeds $75,000 ($150,000 in the case of a joint return); this subparagraph shall apply only if the taxpayer and the taxpayer's spouse file a joint return

Codified at IRC §151(d)(5)(C) (added by OBBBA §70103): (C)(i)-(ii) amount per qualified individual, (C)(iii)(I) the 6% phase-out, (C)(v) joint-return requirement. Code comments cited subparagraphs (A)/(B); corrected 2026-09-28.

OBBBA §70103 effective date (2025 start)

Used by: The senior deduction (Schedule 1-A). Status: verified.

• Public Law 119-21 (One Big Beautiful Bill Act), enrolled text (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  SEC. 70103. TERMINATION OF DEDUCTION FOR PERSONAL EXEMPTIONS OTHER THAN TEMPORARY SENIOR DEDUCTION; The amendments made by this section shall apply to taxable years beginning after December 31, 2024. SEC. 70104

IRS: senior deduction per individual ($12,000 couple), 2025-2028

Used by: The senior deduction (Schedule 1-A). Status: verified.

• Working Families Tax Cuts: tax deductions for working Americans and seniors (Internal Revenue Service (newsroom); record) checked 2026-10-12
  Effective for 2025 through 2028, individuals who are age 65 and older may claim an additional deduction of $6,000; $12,000 total for a married couple where both spouses qualify

URL redirects from the old one-big-beautiful-bill-* slug.

§224(c) tips received in a trade or business (not as an employee): deductible only up to that business's net profit

Used by: Tips received in a trade or business (section 224(c)). Status: verified.

• 26 U.S. Code §224(c) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  other than the trade or business of performing services as an employee; exceeds the sum of the deductions (other than the deduction allowed under this section) allocable to the trade or business in which such qualified tips are received
• Occupations That Customarily and Regularly Received Tips; Definition of Qualified Tips (T.D. 10044, final regulations, 26 CFR 1.224-1(e); 91 FR 19026) (Federal Register (Treasury, IRS); record) checked 2026-10-12
  the deduction under section 224 for a trade or business is limited to the individual's net income (without regard to the section 224 deduction) from that trade or business; would include the expenses deducted on the Schedule C for that trade or business; Manicurist O is allowed a qualified tip deduction of only $15,000
• Schedule 1-A (Form 1040) (2026) DRAFT, not for filing (Internal Revenue Service; record) checked 2026-10-12
  Qualified tips received in the course of a trade or business; Schedule C, line 31; Other allocable deductions; Add lines 5 and 7
• Schedule 1-A (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  Do not enter more than the net profit from the trade or business; Add lines 4c and 5

Modelled since federal engine 2.3.2 (API selfEmployedQualifiedTips / spouseSelfEmployedQualifiedTips): the engine's one business per person, its net profit selfEmploymentIncome (Schedule C line 31); the 2026 draft's column (iv), other allocable deductions, is not an input (the final regulations leave whether the half-SE-tax, self-employed health insurance and retirement deductions are allocable outside their scope). Before 2.3.2 the API took every tip in qualifiedTips without this limit.

§224 tips / §225 overtime: SSN required, joint return if married, MAGI = AGI + §911/931/933 exclusions, terminate after 2028; below-the-line (§63(b)(5)-(6), Schedule 1-A -> 1040 line 13b (2025) / 13a (2026 draft))

Used by: No tax on tips (Schedule 1-A Part II); No tax on overtime (Schedule 1-A Part III). Status: verified.

• 26 U.S. Code §224 (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  no deduction shall be allowed under this section unless the taxpayer includes on the return of tax for the taxable year such individual's social security number; the term "modified adjusted gross income" means the adjusted gross income of the taxpayer for the taxable year increased by any amount excluded from gross income under section 911, 931, or 933; this section shall apply only if the taxpayer and the taxpayer's spouse file a joint return for the taxable year; no deduction shall be allowed under this section for any taxable year beginning after december 31, 2028
• 26 U.S. Code §225 (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  no deduction shall be allowed under this section unless the taxpayer includes on the return of tax for the taxable year such individual's social security number; overtime compensation paid to an individual required under section 7 of the fair labor standards act of 1938 that is in excess of the regular rate; no deduction shall be allowed under this section for any taxable year beginning after december 31, 2028
• 26 U.S. Code §63(b) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  (4) the deduction provided in section 170(p), (5) the deduction provided in section 224, (6) the deduction provided in section 225
• Schedule 1-A (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  modified adjusted gross income (magi) amount enter the amount from form 1040, 1040-sr, or 1040-nr, line 11b; you and/or your spouse who received qualified tips must have a valid social security number to claim the deduction; enter the smaller of the amount on line 6 or $25,000; divide line 10 by $1,000. if the resulting number isn't a whole number, decrease the result to the next lower whole number; enter the smaller of the amount on line 14c or $12,500 ($25,000 if married filing jointly); add lines 13, 21, 30, and 37. enter here and on form 1040 or 1040-sr, line 13b
• Schedule 1-A (Form 1040) 2026 DRAFT (Internal Revenue Service; record) checked 2026-10-12
  add lines 15, 27, 36, and 43. enter here and on form 1040, 1040-sr, or 1040-nr, line 13a

Also extends rule overtime. Senior deduction interaction: existing rules senior/senior_eff; the same Schedule 1-A line-3 MAGI feeds the senior phase-out (Sch 1-A line 31 in 2025). Not an above-the-line adjustment: Schedule 1-A total goes to Form 1040 line 13b (2025) / 13a (2026 draft), after AGI (line 11b), so it does not reduce AGI, NIIT MAGI, IRMAA MAGI or §86 provisional income. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

No tax on tips §224

Used by: No tax on tips (Schedule 1-A Part II). Status: verified.

• 26 U.S. Code § 224 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall not exceed $25,000; by $100 for each $1,000 by which the taxpayer's modified adjusted gross income exceeds $150,000 ($300,000 in the case of a joint return)

Modelled since federal engine 2.0 W2 (Schedule 1-A; API fields qualifiedTips / qualifiedOvertime).

No tax on overtime §225

Used by: No tax on overtime (Schedule 1-A Part III). Status: verified.

• 26 U.S. Code § 225 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall not exceed $12,500 ($25,000 in the case of a joint return)

Modelled since federal engine 2.0 W2 (Schedule 1-A; API fields qualifiedTips / qualifiedOvertime).

OBBBA §70105 changes to §199A: phase-in range $75,000/$150,000 (not indexed); §199A(i) $400 minimum deduction for >= $1,000 active QBI (material participation), indexed after 2026 (base 2025, round to nearest $5); termination repealed

Used by: Qualified business income deduction (Forms 8995 / 8995-A). Status: verified.

• 26 U.S. Code §199A(b)(3)(B), (i) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  exceeds the threshold amount, but does not exceed the sum of the threshold amount plus $75,000 ($150,000 in the case of a joint return); the deduction allowed under subsection (a) for the taxable year shall be equal to the greater of- (a) the amount of such deduction determined without regard to this subsection, or (b) $400; a taxpayer whose aggregate qualified business income with respect to all active qualified trades or businesses of the taxpayer for such taxable year is at least $1,000; in which the taxpayer materially participates (within the meaning of section 469(h)); determined by substituting "calendar year 2025" for "calendar year 2016" in subparagraph (a)(ii) thereof. if any increase under this paragraph is not a multiple of $5, such increase shall be rounded to the nearest multiple of $5; prior to amendment, text read as follows: "this section shall not apply to taxable years beginning after december 31, 2025."
• Public Law 119-21 §70105 (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  sec. 70105. extension and enhancement of deduction for qualified business income; minimum deduction for active qualified business income
• Rev. Proc. 2025-32 §2.12 and §4.26 (Internal Revenue Service; record) checked 2026-10-12
  section 70105 of the obbba amended § 199a(i) to add a minimum deduction of $400; the $400 and $1,000 amounts in § 199a(i) will be adjusted for inflation for taxable years beginning after 2026; married individuals filing joint returns $403,500 $553,500 married individuals filing separate returns $201,775 $276,775 all other returns $201,750 $276,750
• Instructions for Form 8995 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  there is a minimum qualified business income deduction of $400 for taxpayers whose aggregate qualified business income for such taxable year is at least $1,000; if the smaller of line 10 or 14 is less than $400, enter $400 if the aggregate qualified business income from lines 1i through 1v, column (c) with respect to all qualified trades or businesses in which you materially participated; deduction amount determined under section 199a, subject to the applicable limitations

Is the $400 minimum limited by taxable income? The statute does not say so: §199A(i)(1) sets the deduction to 'the greater of' the regular amount or $400, and the regular amount is the one that carries the 20%-of-taxable-income limit. The TY2026 draft 8995 line 17 is 'the greater of line 15 or line 16' and the draft instructions say to enter $400 when 'the smaller of line 10 or 14 is less than $400'. So on the form the $400 is NOT capped by the income limitation (line 14). The draft line-16 text (split across a page break) does add 'subject to the applicable limitations', which it does not define. Taxable income itself cannot go below zero: 2026 draft Form 1040 line 15 reads 'if zero or less, enter -0-'. The net effect is that the deduction can reduce taxable income to 0 and no further. An engine that allows $400 when taxable income before QBI is 0 matches the statute and the draft form. Capping it at taxable income gives the same taxable income, because line 15 is floored at 0, but reports a different line 13b. Phase-in range amounts ($75,000/$150,000) have no inflation clause in §199A; only the threshold (e)(2) is indexed. Rev. Proc. 2025-32 phase-in end = threshold + 75,000/150,000. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

§199A threshold / phase-in end 2026

Used by: Qualified business income deduction (Forms 8995 / 8995-A). Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Married Individuals Filing Joint Returns $403,500 $553,500 Married Individuals Filing Separate Returns $201,775 $276,775 All Other Returns $201,750 $276,750

§4.26.

The K-1s' section 199A information (QBI, W-2 wages, UBIA, SSTB) as one more trade or business on Form 8995 / 8995-A; passive QBI is QBI; guaranteed payments are not

Used by: Qualified business income deduction (Forms 8995 / 8995-A). Status: verified.

• Partner's Instructions for Schedule K-1 (Form 1065) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Code Z. Section 199A information. Generally, you may
• Shareholder's Instructions for Schedule K-1 (Form 1120-S) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Code V. Section 199A information. Generally, you may
• Beneficiary's Instructions for Schedule K-1 (Form 1041) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Code I. Section 199A information. Generally, you may be
• Instructions for Form 8995 (2025) (Internal Revenue Service; record) checked 2026-10-12
  disallowed or limited, including the basis, at-risk, passive loss, or; Amounts received as guaranteed payments.

The aggregation of the K-1 businesses into one column is the caller's (an aggregation election or one business); the section 199A(i) minimum counts it only as an active business (k1QbiActive).

Taxable income (§63(a), (b))

Used by: Total deductions; Taxable income. Status: verified.

• 26 U.S. Code § 63 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income minus the deductions allowed by this chapter; adjusted gross income, minus

Added 2026-09-28 (A1/DOC1): a source for a Form 1040 composition step of the federal engine; every quote checked with scripts/check_state_tax_sources.py --url/--expect.

2026 ordinary brackets Single

Used by: Tax: the brackets and the capital-gains worksheet; Tax: the Tax Table below $100,000. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  TABLE 3 - Section 1(j)(2)(C) - Unmarried Individuals (other than Surviving Spouses and Heads of Households) If Taxable Income Is: The Tax Is: Not over $12,400; Over $105,700 but not over $201,775 $17,966 plus 24%; Over $201,775 but not over $256,225 $41,024 plus 32%; Over $256,225 but not over $640,600 Over $640,600 $58,448 plus 35% of the excess over $256,225 $192,979.25 plus 37% of the excess over $640,600

PDF column order interleaves the last two Single rows; snippet matches the extracted order.

2026 ordinary brackets MFJ

Used by: Tax: the brackets and the capital-gains worksheet; Tax: the Tax Table below $100,000. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Not over $24,800 10% of the taxable income; Over $24,800 but not over $100,800 $2,480 plus 12% of the excess over $24,800; Over $403,550 but not over $512,450 $82,048 plus 32% of the excess over $403,550; Over $512,450 but not over $768,700 $116,896 plus 35%; Over $768,700 $206,583.50 plus 37% of the excess over $768,700; $35,932 plus 24% of the excess over $211,400

2026 ordinary brackets MFS

Used by: Tax: the brackets and the capital-gains worksheet; Tax: the Tax Table below $100,000. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Over $256,225 but not over $384,350 $58,448 plus 35% of the excess over $256,225; Over $384,350 $103,291.75 plus 37% of the excess over $384,350

2026 ordinary brackets HOH

Used by: Tax: the brackets and the capital-gains worksheet; Tax: the Tax Table below $100,000. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Not over $17,700 10% of the taxable income; Over $17,700 but not over $67,450 $1,770 plus 12%; Over $67,450 but not over $105,700 $7,740 plus 22%; Over $105,700 but not over $201,750 $16,155 plus 24%; Over $201,750 but not over $256,200 $39,207 plus 32%; Over $256,200 but not over $640,600 $56,631 plus 35%; Over $640,600 $191,171 plus 37%

2026 LTCG 0%/15% max amounts

Used by: Tax: the brackets and the capital-gains worksheet; Tax: the Schedule D Tax Worksheet. Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Married Individuals Filing Joint Returns and Surviving Spouse $98,900 $613,700 Married Individuals Filing Separate Returns $49,450 $306,850 Heads of Household $66,200 $579,600 All Other Individuals $49,450 $545,500

§4.03.

Qualified dividends taxed as net capital gain (QDCG worksheet), incl. worksheet line 25 (never above the regular tax)

Used by: Tax: the brackets and the capital-gains worksheet; Qualified dividends (line 3a). Status: verified.

• 26 U.S. Code § 1 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  means net capital gain (determined without regard to this paragraph) increased by qualified dividend income; substituting "121-day period" for "91-day period"
• Publication 505 (2026), Tax Withholding and Estimated Tax (Internal Revenue Service; record) checked 2026-10-12
  Enter your qualified dividends expected for 2026; Enter your net capital gain expected for 2026
• Form 1040 and 1040-SR Instructions 2025 (Internal Revenue Service; record) checked 2026-10-12
  Enter the smaller of line 15 or line 16 of Schedule D. If either line 15 or line 16 is blank or a loss, enter -0-; Tax on all taxable income. Enter the smaller of line 23 or line 24
• Form 1099-DIV (Internal Revenue Service; record) checked 2026-10-12
  1a Total ordinary dividends; 1b Qualified dividends
• Publication 550, Investment Income and Expenses (Internal Revenue Service; record) checked 2026-10-12
  You must have held the stock for more than 60 days during the 121-day period that begins 60 days before the ex-dividend date

fed2/w3a (R1). The holding-period test (the 121-day period) is assumed met for every dividend entered as qualified. Worksheet line 25 is applied on returns with R1/R2 amounts only; the 1.0.0 path (long-term gain alone) does not apply it (defects ledger 2026-09-28, open). The holding-period test (more than 60 days in the 121-day period that begins 60 days before the ex-dividend date; IRS Pub 550) is taken as met: every dividend the caller calls qualified is taxed as qualified. Stated in the API's notModeled list, on /methodology.html and in the app's yield hint.

The IRS Tax Table: Form 1040 line 16 below $100,000 (IRC §3)

Used by: Tax: the Tax Table below $100,000. Status: verified.

• 26 U.S. Code § 3 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  In lieu of the tax imposed by section 1, there is hereby imposed for each taxable year on the taxable income of every individual; the amounts of the tax shall be computed on the basis of the rates prescribed by section 1; The Secretary may provide that this section shall apply also for any taxable year to individuals who itemize their deductions
• Instructions for Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  If your taxable income is less than $100,000, you must use the Tax Table; Figure the tax on the amount on line 5. If the amount on line 5 is less than $100,000, use the Tax Table; Figure the tax on the amount on line 1. If the amount on line 1 is less than $100,000, use the Tax Table; The amount shown where the taxable income line and filing status column meet is $2,562

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect. The construction (midpoint, half-dollar rounding up, the row widths) was verified on every row of the 2025 table (i1040tt.pdf, which now redirects to p1040.pdf): 2,062 rows x 4 filing statuses, 0 mismatches against the 2025 rate schedules. The 2026 table is not published; the engine builds it the same way on the 2026 schedules. Only POST /api/federal-tax and libfedtax apply it (taxTable, default true). The planner (/api/simulate) and the ACA bridge use the rate schedules on every dollar: their years are projections whose tables are not published and their solvers need a continuous tax; the difference is at most about half a row times the marginal rate plus rounding in a year.

Foreign tax credit without Form 1116: §904(j) - all foreign income qualified passive (payee statement), creditable taxes <= $300 ($600 joint), election; Schedule 3 line 1

Used by: Foreign tax credit without Form 1116 (the section 904(j) election). Status: verified.

• 26 U.S. Code §904(j) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  the entire amount of such individual's gross income for the taxable year from sources without the united states consists of qualified passive income; the amount of the creditable foreign taxes paid or accrued by the individual during the taxable year does not exceed $300 ($600 in the case of a joint return); such item of income is shown on a payee statement furnished to the individual
• 26 U.S. Code §901(a) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  if the taxpayer chooses to have the benefits of this subpart, the tax imposed by this chapter shall, subject to the limitation of section 904, be credited
• Instructions for Form 1040 (2025), Schedule 3 line 1 (Internal Revenue Service; record) checked 2026-10-12
  you don't have to complete form 1116 to take this credit if all of the following apply; the total of your foreign taxes wasn't more than $300 (not more than $600 if married filing jointly); you held the stock or bonds on which the dividends or interest were paid for at least 16 days; enter on line 1 the smaller of (a) your total foreign taxes, or (b) the total of the amounts on form 1040 or 1040-sr, line 16, and schedule 2, line 1a
• Instructions for Form 1116 (2025) (Internal Revenue Service; record) checked 2026-10-12
  by making this election, the foreign tax credit limitation (lines 15 through 23 of the form) won't apply to you; your total creditable foreign taxes aren't more than $300 ($600 if married filing a joint return)

Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

FTC limitation §904(a) (tax x foreign-source taxable income / worldwide taxable income), §904(b)(2) capital-gain rate-differential adjustment (Form 1116 QD/CG adjustment 0.4054 / 0.5405, 25% / 28% groups 0.6757 / 0.7568, adjustment exception), carryback 1 / carryforward 10 (§904(c)); line 18 adds back the senior deduction

Used by: Foreign tax credit with Form 1116 (the section 904(a) limit, passive category); The AMT foreign tax credit (Form 6251 line 8). Status: verified.

• 26 U.S. Code §904(a)-(c) (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  the total amount of the credit taken under section 901(a) shall not exceed the same proportion of the tax against which such credit is taken which the taxpayer's taxable income from sources without the united states (but not in excess of the taxpayer's entire taxable income) bears to his entire taxable income for the same taxable year; the taxable income in the case of an individual, estate, or trust shall be computed without any deduction for personal exemptions under section 151 or 642(b); reduced by the rate differential portion of foreign source net capital gain; in the first preceding taxable year and in any of the first 10 succeeding taxable years, in that order
• Form 1116 (2025) (Internal Revenue Service; record) checked 2026-10-12
  individuals: enter the sum of (i) form 1040, 1040-sr, or 1040-nr, line 11b, minus form 1040, 1040-sr, or 1040-nr, line 14, and (ii) schedule 1-a (form 1040), line 37; divide line 17 by line 18. if line 17 is more than line 18, enter "1"; individuals: enter the total of form 1040, 1040-sr, or 1040-nr, line 16, and schedule 2 (form 1040), line 1z; multiply line 20 by line 19 (maximum amount of credit)
• Instructions for Form 1116 (2025) (Internal Revenue Service; record) checked 2026-10-12
  this deduction is reported on schedule 1-a (form 1040), line 37, and needs to be removed from taxable income for purposes of computing the foreign tax credit limitation; you must adjust the amount of your foreign source qualified dividends and capital gain distributions if both of the following apply; line 5 of the qualified dividends and capital gain tax worksheet is greater than zero. • line 23 of the qualified dividends and capital gain tax worksheet is less than line 24 of that worksheet; the amount of your foreign source capital gain distributions plus the amount of your foreign source qualified dividends is less than $20,000; multiply your foreign source qualified dividends or capital gain distributions in each separate category by 0.4054 if the foreign source qualified dividends or capital gain distributions are taxed at a rate of 15%, and by 0.5405 if they are taxed at a 20% rate; $394,600 if married filing jointly or qualifying surviving spouse, b. $197,300 if married filing separately, c. $197,300 if single, or d. $197,300 if head of household
• Form 1116 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  subtract form 1040, 1040-sr, or 1040-nr, line 14, from form 1040, 1040-sr, or 1040-nr, line 11b. increase the result by the amount from schedule 1-a (form 1040), line 43
• Publication 514, Foreign Tax Credit for Individuals (Internal Revenue Service; record) checked 2026-10-12
  multiply the applicable amount of the net capital gain by 0.6757; multiply the applicable amount of the foreign source net capital gain by 0.7568

The adjustment-exception ceiling in the TY2025 instructions ($394,600 / $197,300) is a TY2025 figure. The i1116 file on irs-dft is still TY2025 text, so no 2026 figure is sourced here. Status: unknown for 2026. The senior deduction is removed from the line-18 denominator because §904(b)(1) excludes §151 deductions and the senior deduction sits in §151(d)(5)(C). Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

AMT exemption / phase-out 2026 (the reference amounts; the engine's are FedWorkParams amt_*, rule amt_2026_params)

Used by: Alternative minimum tax (Form 6251). Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Joint Returns or Surviving Spouses Exemption amount $140,200 Unmarried Individuals (other than Surviving Spouses) $90,100 Married Individuals Filing Separate Returns $70,100; Joint Returns or Surviving Spouses $1,000,000 $1,280,400 Unmarried Individuals (other than Surviving Spouses) $500,000 $680,200

Modelled since federal engine 2.0 W3 (Form 6251 on every API return); the capital-gains / TLH tool figures it through the engine since W6 (2026-10-01).

AMT 2026 (Rev. Proc. 2025-32 §4.10 + §55 as amended by P.L. 119-21 §70107): exemption, 26%/28% breakpoint, phase-out thresholds and 50% phase-out rate

Used by: Alternative minimum tax (Form 6251). Status: verified.

• Rev. Proc. 2025-32 §4.10, §2.07 (Internal Revenue Service; record) checked 2026-10-12
  under § 55(b)(1), the excess taxable income above which the 28 percent tax rate applies is: filing status excess taxable income married individuals filing separate returns $122,250 all other taxpayers $244,500; joint returns or surviving spouses $1,000,000 $1,280,400 unmarried individuals (other than surviving spouses) $500,000 $680,200 married individuals filing separate returns $500,000 $640,200; section 55(d)(4)(b) as amended provides that the $1,000,000 amount described in § 55(d)(4)(a)(ii)(i) is not adjusted for inflation for any taxable year beginning before january 1, 2027
• 26 U.S. Code §55 (Legal Information Institute (Cornell) - U.S. Code; record) checked 2026-10-12
  26 percent of so much of the taxable excess as does not exceed $175,000, plus (ii) 28 percent of so much of the taxable excess as exceeds $175,000; the amount determined under the preceding sentence shall be reduced by the alternative minimum tax foreign tax credit for the taxable year; by substituting "$1,000,000" for "$150,000" in subparagraph (a), (ii) by substituting "50 percent of the dollar amount applicable under subparagraph (a)" for "$112,500" in subparagraph (b); (iv) by substituting "50 percent" for "25 percent"; (2026, in the case of the $1,000,000 amount in subparagraph (a)(ii)(i)); "calendar year 2025", in the case of the $1,000,000 amount in subparagraph (a)(ii)(i); any increased amount determined under clause (i) shall be rounded to the nearest multiple of $100
• Public Law 119-21 §70107 (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  sec. 70107. extension of increased alternative minimum tax exemption amounts and modification of phaseout thresholds
• Form 6251 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  if line 6 is $244,500 or less ($122,250 or less if married filing separately), multiply line 6 by 26% (0.26). otherwise, multiply line 6 by 28% (0.28) and subtract $4,890 ($2,445 if married filing separately) from the result; single or head of household . . . . . . $ 500,000 . . . . . $ 90,100 married filing jointly or qualifying surviving spouse 1,000,000 . . . . . 140,200 married filing separately . . . . . . . 500,000 . . . . . 70,100; if married filing separately and line 4 is more than $640,200, see instructions
• Instructions for Form 6251 (2025) (Internal Revenue Service; record) checked 2026-10-12
  the exemption amount on form 6251, line 5, has increased to $88,100 ($137,000 if married filing jointly or qualifying surviving spouse; $68,500 if married filing separately); the amount used to determine the phaseout of your exemption has increased to $626,350 ($1,252,700 if married filing jointly or qualifying surviving spouse)

2026 phase-out rate 50%: Rev. Proc. complete-phaseout amounts confirm it, e.g. 1,000,000 + 140,200 / 0.5 = 1,280,400. TY2025 used 25% ($1,252,700 threshold). That was the pre-OBBBA $1,000,000 figure indexed from 2017 with 2025 as the last year; OBBBA reset it to $1,000,000 in 2026. The breakpoint $175,000 is indexed under §55(d)(3) (base 2011, nearest $100); MFS is half (§55(b)(1)(C)). It is NOT covered by the §55(d)(4) base-year change. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Form 6251 structure relevant to retirees (TY2025 final; TY2026 draft keeps lines): line 1a/1b (senior deduction added back), 2a (SALT or standard deduction add-back), 2g private activity bond interest, 2i ISO, Part III keeps 0/15/20% on QD/CG, line 8 AMTFTC; line 8 AMT Form 1116: line 18 = Form 6251 line 4, or the AMT Worksheet for Line 18 (lines 23, 30 x 0.4643, 33 x 0.2857, 36 x 0.1071 off line 4) with the foreign QD at 0.5357 / 0.7143 / 0.8929; line 8 blank when line 10 >= line 7

Used by: Alternative minimum tax (Form 6251); The AMT foreign tax credit (Form 6251 line 8). Status: verified.

• Form 6251 (2025) (Internal Revenue Service; record) checked 2026-10-12
  subtract schedule 1-a (form 1040), line 37, from form 1040, 1040-sr, or 1040-nr, line 14; if filing schedule a (form 1040), enter the taxes from schedule a, line 7; otherwise, enter the amount from form 1040 or 1040-sr, line 12e; interest from specified private activity bonds exempt from the regular tax; exercise of incentive stock options (excess of amt income over regular tax income); complete part iii on the back and enter the amount from line 40 here; alternative minimum tax foreign tax credit (see instructions); amt. subtract line 10 from line 9. if zero or less, enter -0-. enter here and on schedule 2 (form 1040), line 2
• Instructions for Form 6251 (2025) (Internal Revenue Service; record) checked 2026-10-12
  the deduction is treated as a personal exemption that is added back to alternative minimum taxable income as an adjustment under section 56(b)(5)(d); if you aren't filing schedule a (form 1040), then enter the standard deduction amount that you reported on form 1040 or 1040-sr, line 12e; enter on line 2g interest income from "specified private activity bonds" reduced (but not below zero) by any deduction that would have been allowable if the interest were includible in gross income for the regular tax; if you made an election to claim the foreign tax credit on your 2025 tax return without filing form 1116, your amtftc is the same as the foreign tax credit on schedule 3 (form 1040), line 1; you will figure the amtftc using the same limitation rules that apply to the foreign tax credit for regular tax purposes, but with amt amounts; enter the amount from line 4 of form 6251 on line 18 of the amt form 1116; leave line 8 blank; multiply your foreign source qualified dividends in each separate category by 0.5357 if the foreign source qualified dividends are taxed at a rate of 15%, and by 0.7143 if they are taxed at a rate of 20%; when the amount of any amt gain is in the 25% rate group, multiply it by 0.8929 instead of the number used for regular tax; multiply line 4 of the worksheet by 0.1071 (instead of the number used for regular tax)
• Form 6251 (2026) DRAFT (Internal Revenue Service; record) checked 2026-10-12
  subtract schedule 1-a (form 1040), line 43, from form 1040, 1040-sr, or 1040-nr, line 14; if you reported capital gain distributions directly on form 1040 or 1040-sr, line 7a; you reported qualified dividends on form 1040 or 1040-sr, line 3a

Schedule 1-A tips/overtime/car-loan deductions stay deducted for AMT: line 1a removes only the senior line (37 / 2026 draft 43) from line 14. TY2026 draft instructions for 6251 on irs-dft are still the TY2025 text. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Minimum tax credit (Form 8801) - note only, not modelled

Used by: Alternative minimum tax (Form 6251). Status: verified.

• Form 8801 (2025) (Internal Revenue Service; record) checked 2026-10-12
  credit for prior year minimum taxindividuals, estates, and trusts; minimum tax credit and carryforward to 2026
• Schedule 3 (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  credit for prior year minimum tax. attach form 8801

Only the deferral items (e.g. ISO spread) create the credit; exclusion items (SALT, standard deduction, private activity bond interest) do not. This is why 8801 needs multi-year state and is out of scope for a single-year engine. Federal engine 2.0 W0 (2026-09-30): merged from research/data/federal-engine-2-sources.json; engine locations are filled in by the wave that models the rule (docs/federal-engine-2/PLAN.md).

Form 1040 (2025) lines 16-24, 27a, 28 and Schedule 3 (2025) lines 1, 4, 6d, 8

Used by: Form 1040 lines 18 to 22: the order of the nonrefundable credits. Status: verified.

• Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Amount from Schedule 2, line 3; Add lines 16 and 17; Child tax credit or credit for other dependents from Schedule 8812; Amount from Schedule 3, line 8; Add lines 19 and 20; Subtract line 21 from line 18. If zero or less, enter -0-; Add lines 22 and 23. This is your total tax; Earned income credit (EIC); Additional child tax credit (ACTC) from Schedule 8812; Add lines 27a, 28, 29, 30, and 31. These are your total other payments and refundable credits
• Schedule 3 (Form 1040) 2025, Additional Credits and Payments (Internal Revenue Service; record) checked 2026-10-12
  Foreign tax credit. Attach Form 1116 if required; Retirement savings contributions credit. Attach Form 8880; Credit for the elderly or disabled. Attach Schedule R; Add lines 1 through 4, 5a, 5b, and 7. Enter here and on Form 1040, 1040-SR, or 1040-NR, line 20

Added 2026-10-06 (fed/2.1, engine 2.1.0). The EIC and the ACTC are payments (line 32), not part of line 24.

§22 credit for the elderly or the disabled (Schedule R)

Used by: Credit for the elderly or the disabled (Schedule R). Status: verified.

• 26 U.S. Code § 22 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  an amount equal to 15 percent of such individual's section 22 amount for such taxable year; who has attained age 65 before the close of the taxable year, or (2) who retired on disability before the close of the taxable year and who, when he retired, was permanently and totally disabled; (i) $5,000 in the case of a single individual, or a joint return where only one spouse is a qualified individual, (ii) $7,500 in the case of a joint return where both spouses are qualified individuals, or (iii) $3,750 in the case of a married individual filing a separate return; the initial amount shall not exceed the disability income for the taxable year; the initial amount shall not exceed the sum of $5,000 plus the disability income for the taxable year of the spouse who has not attained age 65 before the close of the taxable year; which is excluded from gross income and payable under- (I) title II of the Social Security Act; (1) $7,500 in the case of a single individual, (2) $10,000 in the case of a joint return, or (3) $5,000 in the case of a married individual filing a separate return, the section 22 amount shall be reduced by one-half of the excess of the adjusted gross income over $7,500, $10,000, or $5,000, as the case may be; Except in the case of a husband and wife who live apart at all times during the taxable year, if the taxpayer is married at the close of the taxable year, the credit provided by this section shall be allowed only if the taxpayer and his spouse file a joint return for the taxable year
• Schedule R (Form 1040) 2025, Credit for the Elderly or the Disabled (Internal Revenue Service; record) checked 2026-10-12
  Box 1, 2, 4, or 7 . . . . . . . . . . . . $5,000; Box 6, add $5,000 to the taxable disability income of the spouse who was under age 65. Enter the total.; If you completed line 11, enter the smaller of line 10 or line 11. All others, enter the amount from line 10; Nontaxable part of social security benefits and nontaxable part of railroad retirement benefits treated as social security (see instructions); Enter the amount from Form 1040 or 1040-SR, line 11a; Box 3, 4, 5, 6, or 7 . . . . . . $10,000; Subtract line 15 from line 14. If zero or less, enter -0-; Enter one-half of line 16; Add lines 13c and 17; Subtract line 18 from line 12. If zero or less, stop; you can't take the credit.; Multiply line 19 by 15% (0.15); Tax liability limit. Enter the amount from the Credit Limit Worksheet in the instructions; Credit for the elderly or the disabled. Enter the smaller of line 20 or line 21. Also enter this amount on Schedule 3 (Form 1040), line 6d; You were 65 or older and you lived apart from your spouse for all of 2025
• Instructions for Schedule R (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  You are considered age 65 on the day before your 65th birthday. As a result, if you were born on January 1, 1961, you are considered to be age 65 at the end of 2025.; On January 1, 2025, you had not reached mandatory retirement age; Enter the amount from Form 1040 or 1040-SR, line 18; Enter the amount from Schedule 3 (Form 1040), lines 1, 2, and 6l; Subtract line 2 from line 1. Enter this amount on Schedule R (Form 1040), line 21. If zero or less, stop; you can't take this credit; the amount to enter on this line is generally the difference between the amounts entered on Form 1040 or 1040-SR, line 6a and line 6b; single, head of household, or qualifying surviving spouse $17,500 or more $5,000 married filing jointly and only one spouse is a qualifying individual $20,000 or more $5,000 married filing jointly and both spouses are qualifying individuals $25,000 or more $7,500 married filing separately and you lived apart from your spouse for all of 2025 $12,500 or more $3,750

Added 2026-10-06 (fed/2.1, engine 2.1.0). Correction to the 2.1 design: the Schedule R Credit Limit Worksheet subtracts Schedule 3 lines 1, 2 and 6l (not lines 1-3): the elderly credit is taken before the education credits. Of those lines the engine has only line 1 (foreign tax credit). The §22 amounts are fixed in law (no inflation clause): rule fed-elderly-credit of research/data/federal-tax-indexing.json. Table 1's AGI limits are not separate parameters: initial amount x 2 + the §22(d) threshold. Permanent and total disability (physician's statement) and the mandatory-retirement-age test are the caller's assertion (taxableDisabilityIncome).

§25B saver's credit (Form 8880) for 2026, and its end for retirement contributions after 2026

Used by: Saver's credit (Form 8880). Status: verified.

• 26 U.S. Code § 25B (with the Pub. L. 119-21 §70116 amendment notes) (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  an amount equal to the applicable percentage of so much of the qualified retirement savings contributions of the eligible individual for the taxable year as do not exceed $2,000; (A) if the adjusted gross income of the taxpayer is not over $30,000, 50 percent, (B) if the adjusted gross income of the taxpayer is over $30,000 but not over $32,500, 20 percent, (C) if the adjusted gross income of the taxpayer is over $32,500 but not over $50,000, 10 percent, and (D) if the adjusted gross income of the taxpayer is over $50,000, zero percent; a dollar amount equal to 75 percent of such dollar amount; a dollar amount equal to 50 percent of such dollar amount; the term "eligible individual" means any individual if such individual has attained the age of 18 as of the close of the taxable year; any individual who is a student (as defined in section 152(f)(2)); in the case of any taxable year beginning before January 1, 2027- (i) the amount of the qualified retirement contributions (as defined in section 219(e)) made by the eligible individual; shall be reduced (but not below zero) by the aggregate distributions received by the individual during the testing period from any entity of a type to which contributions under paragraph (1) may be made; (i) such taxable year, (ii) the 2 preceding taxable years, and (iii) the period after such taxable year and before the due date (including extensions) for filing the return of tax for such taxable year; any distribution received by the spouse of such individual shall be treated as received by such individual if such individual and spouse file a joint return; applicable to taxable years beginning after Dec. 31, 2026, subsection (a) of this section is amended by striking "$2,000" and inserting "$2,100"; Pub. L. 119-21, § 70116(a)(2), repealed Pub. L. 117-328, § 103(e)(1)
• 26 U.S. Code § 6433 - Saver's Match (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Any eligible individual who makes qualified retirement savings contributions for the taxable year shall be allowed a matching contribution
• Notice 2025-67: 2026 retirement plan limitations (Internal Revenue Service; record) checked 2026-10-12
  the limitation under section 25B(b)(1)(B) is increased from $51,000 to $52,500; the limitation under section 25B(b)(1)(B) is increased from $38,250 to $39,375; the limitation under section 25B(b)(1)(B) is increased from $25,500 to $26,250
• Form 8880 (2025), Credit for Qualified Retirement Savings Contributions (with instructions) (Internal Revenue Service; record) checked 2026-10-12
  was born after January 1, 2008; Certain distributions received after 2022 and before the due date (including extensions) of your 2025 tax return (see instructions). If married filing jointly, include both spouses' amounts in both columns.; In each column, enter the smaller of line 5 or $2,000; Limitation based on tax liability. Enter the amount from the Credit Limit Worksheet in the instructions; Credit for qualified retirement savings contributions. Enter the smaller of line 10 or line 11 here and on Schedule 3 (Form 1040), line 4; $47,500 $51,000 0.2 0.1 0.0; Distributions not taxable as the result of a rollover or a trustee-totrustee transfer.; Loans from a qualified employer plan treated as a distribution.; Distributions from an inherited IRA by a nonspousal beneficiary.; Enter the total of your credits from Schedule 3, lines 1 through 3, 6d, and 6l; Under the SECURE 2.0 Act of 2022, beginning with 2027 tax returns, the saver's credit will be replaced by a saver's match that will be deposited by the government directly into your retirement account. Starting with 2027 tax returns, Form 8880 will only be used to claim the saver's credit for ABLE account contributions.

Added 2026-10-06 (fed/2.1, engine 2.1.0). The 2026 50% and 10% tops are also quoted in rule roth_savers. Correction to the 2.1 design: SECURE 2.0 §103 did not replace §25B outright. Its §25B amendment (§103(e)(1)) was repealed by Pub. L. 119-21 §70116(a)(2); §25B(d)(1) as amended by §70116(a)(1) counts the retirement contributions only for taxable years beginning before January 1, 2027, and keeps the credit (cap $2,100 from 2027) for ABLE contributions by the designated beneficiary. The engine's inputs are retirement contributions, so its credit is 0 in 2027 and later; ABLE contributions are not an engine input. Form 8880 line 4: on a joint return each spouse's distributions reduce BOTH columns (§25B(d)(2)(D)). Correction to the 2.1 design: the Credit Limit Worksheet also subtracts Schedule 3 line 6l (not in the engine). Age 18 follows the day-before-birthday rule (Form 8880: not eligible if born after January 1, 2008, for 2025).

Roth IRA phase-out and Saver's credit 2026

Used by: Saver's credit (Form 8880). Status: verified.

• Notice 2025-67: 2026 retirement plan limitations (Internal Revenue Service; record) checked 2026-10-12
  between $242,000 and $252,000 for married couples filing jointly; between $153,000 and $168,000; married taxpayers filing a joint return is increased from $47,500 to $48,500; is increased from $79,000 to $80,500; household is increased from $35,625 to $36,375; is increased from $59,250 to $60,375; all other taxpayers is increased from $23,750 to $24,250; is increased from $39,500 to $40,250

Engine 2.1.0 (fed/2.1): the saver's credit AGI table of Form 8880 is FedWorkParams.savers_agi in backend/src/federal_tax.c; the 20% tier tops and the statute/form quotes are in rule savers_credit_25b; indexing rule fed-savers-agi.

Child tax credit 2026

Used by: Child tax credit, credit for other dependents and additional child tax credit (Schedule 8812). Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  the maximum amount of the credit allowed under § 24(a) is $2,200; the amount used in § 24(d)(1)(A) to determine the amount of the credit under § 24 that may be refundable is $1,700

§4.05. Engine 2.1.0 (fed/2.1): Schedule 8812 in backend/src/federal_tax.c (FedWorkParams.ctc_per_child, ctc_refundable) and its JS mirror frontend/js/calc/federal-tax-engine-2026.js; form lines in rule ctc_8812; indexing rules fed-ctc and fed-ctc-refundable.

CTC statutory: $400k/$200k threshold, $500 ODC, $2,500 floor

Used by: Child tax credit, credit for other dependents and additional child tax credit (Schedule 8812). Status: verified.

• 26 U.S. Code § 24 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the threshold amount shall be $400,000 in the case of a joint return ($200,000 in any other case); shall be increased by $500 for each; Subsection (d)(1)(B)(i) shall be applied by substituting "$2,500" for "$3,000"

Engine 2.1.0 (fed/2.1): FedWorkParams.ctc_threshold[0..1], ctc_other_dependent, ctc_earned_floor (fixed in law: indexing rule fed-ctc-fixed); JS mirror frontend/js/calc/federal-tax-engine-2026.js.

§24 child tax credit and credit for other dependents (Schedule 8812 Parts I, II-A, II-B)

Used by: Child tax credit, credit for other dependents and additional child tax credit (Schedule 8812). Status: verified.

• Schedule 8812 (Form 1040) 2025, Credits for Qualifying Children and Other Dependents (Internal Revenue Service; record) checked 2026-10-12
  Enter the amount from line 11a of your Form 1040, 1040-SR, or 1040-NR; Multiply line 4 by $2,200; Multiply line 6 by $500; Married filing jointly-$400,000; All other filing statuses-$200,000; If more than zero and not a multiple of $1,000, enter the next multiple of $1,000.; Multiply line 10 by 5% (0.05); Enter the amount from Credit Limit Worksheet A; Enter the smaller of line 12 or line 13. This is your child tax credit and credit for other dependents; Subtract line 14 from line 12. If zero, stop here; you cannot take the additional child tax credit; x $1,700. Enter the result.; Is the amount on line 18a more than $2,500?; Multiply the amount on line 19 by 15% (0.15) and enter the result; On line 16b, is the amount $5,100 or more?; Withheld social security, Medicare, and Additional Medicare taxes from Form(s) W-2, boxes 4 and 6. If married filing jointly, include your spouse's amounts with yours.; Enter the total of the amounts from Schedule 1 (Form 1040), line 15; Schedule 2 (Form 1040), line 5; Schedule 2 (Form 1040), line 6; and Schedule 2 (Form 1040), line 13; 1040 and 1040-SR filers: Enter the total of the amounts from Form 1040 or 1040-SR, line 27a, and Schedule 3 (Form 1040), line 11.; Enter the larger of line 20 or line 25; This is your additional child tax credit. Enter this amount on Form 1040, 1040-SR, or 1040-NR, line 28
• Instructions for Schedule 8812 (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  If you are completing Part II-B and your employer withheld or you paid Additional Medicare Tax or tier 1 RRTA tax, use the Additional Medicare Tax and RRTA Tax Worksheet, later, to figure the amount to enter on line 21.; Enter the social security tax withheld (Form(s) W-2, box 4,; Enter any amount from Form 8959, line 7; Enter the Additional Medicare Tax withheld (Form 8959, line 22); Enter one-half of the Additional Medicare Tax, if any, on self-employment income (one-half of Form 8959, line 13); Enter the amount from line 18 of your Form 1040, 1040-SR, or 1040-NR.; Schedule 3, line 5b; Schedule 3, line 6m; your earned income from Worksheet B (in your Instructions for Form 1040), line 4b,; Enter any net profit or (loss) from Schedule C, line 31,; Enter the amount from Schedule 1 (Form 1040), line 15; Combine lines 1a, 1b, 2a, 2b, and 2e. If zero or less, stop.
• 26 U.S. Code § 24 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be reduced (but not below zero) by $50 for each $1,000 (or fraction thereof) by which the taxpayer's modified adjusted gross income exceeds the threshold amount; 50 percent of the taxes imposed by section 1401 on the self-employment income of the taxpayer for the taxable year; The amount determined under subsection (d)(1)(A) with respect to any qualifying child shall not exceed $1,400

Added 2026-10-06 (fed/2.1, engine 2.1.0). The 2026 amounts: rules ctc (Rev. Proc. 2025-32 §4.05) and ctc_statute. Credit Limit Worksheet A subtracts Schedule 3 lines 1, 2, 3, 4, 5b, 6d, 6f, 6l and 6m (as the 2.1 design says); of these the engine has 1 (FTC), 4 (saver's) and 6d (elderly). Credit Limit Worksheet B (mortgage interest, adoption, residential clean energy, DC homebuyer credits) is not needed: none of those credits is in the engine. Correction to the 2.1 design: Part II-B line 22 is Schedule 1 line 15 (the deductible HALF of SE tax, §24(d)(2)(A)(ii)), and line 24 subtracts the EIC AND Schedule 3 line 11 (excess social security withheld). Line 21 with Additional Medicare Tax: withheld SS + withheld Medicare + Form 8959 line 7 - Form 8959 line 22, plus one-half of Form 8959 line 13. Line 18a earned income: the EIC Worksheet B line 4b when the EIC is figured; otherwise the Earned Income Worksheet: Form 1040 line 1z + Schedule C line 31 - Schedule 1 line 15 (the same amount). The $5,100 test of line 16b is 3 x $1,700.

EITC 2026 table

Used by: Earned income credit (Form 1040 line 27a). Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Earned Income Amount $13,020 $18,290 $18,290 $8,680 Maximum Amount of Credit $4,427 $7,316 $8,231 $664; Threshold Phaseout Amount (Married Filing Jointly) $31,160 $31,160 $31,160 $18,140 Completed Phaseout Amount (Married Filing Jointly) $58,863 $65,899 $70,244 $26,820; Threshold Phaseout Amount (All other filing statuses) $23,890 $23,890 $23,890 $10,860 Completed Phaseout Amount (All other filing statuses) $51,593 $58,629 $62,974 $19,540; aggregate amount of certain investment income exceeds $12,200

§4.06. Engine 2.1.0 (fed/2.1): FedWorkParams.eitc_earned[0..3], eitc_threshold[2][4], eitc_inv_limit (indexing rules fed-eitc-amounts, fed-eitc-investment-limit); the maximum credit and completed phaseout amounts follow from the earned income amounts, thresholds and the §32(b)(1) percentages. Eligibility, earned income and the EIC Table: rule eitc_rules_32.

EITC credit/phaseout percentages §32(b)(1)

Used by: Earned income credit (Form 1040 line 27a). Status: verified.

• 26 U.S. Code § 32 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  1 qualifying child 34 15.98 2 qualifying children 40 21.06 3 or more qualifying children 45 21.06 No qualifying children 7.65 7.65

Engine 2.1.0 (fed/2.1): the C engine and frontend/js/calc/federal-tax-engine-2026.js apply these percentages (rates: not indexed).

§32 earned income credit: eligibility, earned income, the EIC Table and the investment income worksheet

Used by: Earned income credit (Form 1040 line 27a). Status: verified.

• 26 U.S. Code § 32 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  has attained age 25 but not attained age 65 before the close of the taxable year; the amount of the taxpayer's net earnings from self-employment for the taxable year (within the meaning of section 1402(a)), but such net earnings shall be determined with regard to the deduction allowed to the taxpayer by section 164(f); In the case of an individual who is married, this section shall apply only if a joint return is filed for the taxable year under section 6013.; resides with a qualifying child of the individual for more than one-half of such taxable year; shall have income brackets of not greater than $50 each; In the case of any taxable year beginning after December 31, 2020, and before January 1, 2022; the excess (if any) of- (i) gross income from rents or royalties not derived in the ordinary course of a trade or business; the capital gain net income (as defined in section 1222) of the taxpayer for such taxable year; the aggregate income from all passive activities for the taxable year; In the case of a joint return filed by an eligible individual and such individual's spouse, the phaseout amount determined under subparagraph (A) shall be increased by $5,000.
• Instructions for Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Self-Employed NOT Required To File Schedule SE For example, your net earnings from self-employment were less than $400.; 1a. Enter the amount from Schedule SE, Part I, line 3.; d. Enter the amount from Schedule SE, Part I, line 13.; b. Enter any net profit or (loss) from Schedule C, line 31; and Schedule K-1 (Form 1065), box 14, code A (other than farming)*.; b. Combine lines 1e, 2c, 3, and 4a. This is your total earned income.; Were you, or your spouse if filing a joint return, at least age 25 but under age 65 at the end of 2025? (Check "Yes" if you, or your spouse if filing a joint return, were born after December 31, 1960, and before January 2, 2001.); Are you a married taxpayer whose filing status is married filing separately or head of household?; Caution. This is not a tax table.; 1 50 100 150 50 100 150 200 2 6 10 13 9 26 43 60 10 30 50 70 11 34 56 79; the amount you are looking up from your EIC Worksheet is $2,455, you would enter $842.; Use this column if your filing status is married filing separately and you qualify to claim the EIC.
• Publication 596 (2025), Earned Income Credit (Internal Revenue Service; record) checked 2026-10-12
  A taxpayer is considered to reach age 25 on the day before the taxpayer's 25th birthday. However, the rule for reaching age 65 is different; a taxpayer reaches age 65 on the taxpayer's 65th birthday.; Enter any amount from Form 1040 or 1040-SR, line 2b; Enter the amount from Form 1040 or 1040-SR, line 7a. If the amount on that line is a loss, enter -0-; Enter the total of any net income from passive activities (such as income included on Schedule E, line 26,; Combine the amounts on lines 11 and 12 of this worksheet. (If the result is less than zero, enter -0-.); Add the amounts on lines 1, 2, 3, 4, 7, 10, and 13. Enter the total. This is your investment income; If any of the rental real estate income (or loss) included on Schedule E, line 26, isn't from a passive activity, enter "NPA"

Added 2026-10-06 (fed/2.1, engine 2.1.0). The 2026 amounts: rules eitc (Rev. Proc. 2025-32 §4.06) and eitc_pct (§32(b)(1)). No temporary rule applies to 2026: §32(n) (age 19, no upper age) covered only taxable years beginning in 2021. Correction to the 2.1 design: the age test is NOT the §63(f) day-before rule at both ends. Age 25 is reached the day before the 25th birthday, age 65 on the 65th birthday (Pub 596): for 2026 a childless filer qualifies if born after December 31, 1961 and before January 2, 2002. Correction to the 2.1 design: earned income from self-employment is Schedule SE line 3 (net profit, before the 92.35% factor) minus line 13 (the §164(f) deduction), not net earnings x 92.35%; under the $400 Schedule SE floor it is the Schedule C line 31 profit in full (Worksheet B Part 2). A Schedule C loss reduces earned income. Correction to the 2.1 design (investment income): rental real estate enters Pub 596 Worksheet 1 through the passive-activity lines 11-13, from Schedule E line 26 (after the Form 8582 limit, so an allowed loss offsets other passive income) and floored at 0; a real estate professional's (non-passive, NPA) rental income or loss is not investment income. EIC Table: $50 brackets from $1; the credit is the §32(a)-(b) formula at the bracket midpoint rounded to the nearest dollar (first row $1-$50: 2 / 9 / 10 / 11; $2,450-$2,500 with one child: $842 = 0.34 x 2,475 rounded). MFS filers who qualify use the single column.

§72(t) 10% additional tax; 59½ exception

Used by: The 10% additional tax on early distributions; Form 5329: early distributions; §72(q): the 10% on a nonqualified annuity before 59½. Status: verified.

• 26 U.S. Code § 72 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be increased by an amount equal to 10 percent of the portion of such amount which is includible in gross income; made on or after the date on which the employee attains age 59½

Engine 1.1.0 (age clock): without a birth month the tax applies through the year the owner reaches 59 and not from the year they reach 60; with one, only to the share of the year before 59½ (tax_calculator.c early_withdrawal_penalty_share). The §72(t)(2) exceptions of disability, substantially equal periodic payments and separation from service at 55 (50 for public safety) are modelled (rule 72t_exceptions); others are not.

NIIT §1411 rate and thresholds

Used by: Net investment income tax. Status: verified.

• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  a tax equal to 3.8 percent of the lesser of; in the case of a taxpayer making a joint return under section 6013 or a surviving spouse (as defined in section 2(a)), $250,000; ½ of the dollar amount determined under paragraph (1); in any other case, $200,000

NIIT IRS page

Used by: Net investment income tax. Status: verified.

• Net Investment Income Tax (Internal Revenue Service; record) checked 2026-10-12
  Married filing jointly - $250,000, Married filing separately - $125,000, Single or head of household - $200,000

§1411 net investment income: interest, dividends and net gain (Form 8960 line 5a = Form 1040 line 7a)

Used by: Net investment income tax; Taxable interest (line 2b); Ordinary dividends (line 3b); Total investment income (Form 8960 line 8); Form 8960 line 12: net investment income. Status: verified.

• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income from interest, dividends, annuities, royalties, and rents; the modified adjusted gross income for such taxable year; net investment income for such taxable year
• Instructions for Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Form 1040 or 1040-SR, line 7a

fed2/w3a (R1/R2) introduced the whole-NII base for returns with R1/R2 amounts; engine 1.3.0 (fed2/r13) uses it on every return (the pre-1.3.0 default base left out long-term gain sheltered by an unused deduction; defects ledger 2026-09-28, fixed). Engine 1.5.0 (fed6/f1): nonqualified annuities on line 3 and the Part II deductions (rules niit_annuities, niit_part2).

Medical and dental expenses §213(a) over 7.5% of AGI (Schedule A line 4)

Used by: Medical and dental expenses. Status: verified.

• 26 U.S. Code § 213 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  to the extent that such expenses exceed 7.5 percent of adjusted gross income

SALT cap §164(b)(6)-(7) with the 30% phase-down (Schedule A line 5e)

Used by: State and local taxes paid; The SALT cap and its phase-down; Itemize or take the standard deduction. Status: verified.

• 26 U.S. Code § 164 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  in the case of any taxable year beginning in calendar year 2025, $40,000; in the case of any taxable year beginning in calendar year 2026, $40,400; reduced by 30 percent of the excess (if any) of the taxpayer's modified adjusted gross income over the threshold amount; in the case of any taxable year beginning in calendar year 2026, $505,000; shall not result in the applicable limitation amount being less than $10,000

Modelled: see rule salt_sched_a (the MFS halving, the 101% steps and the Schedule A worksheet).

SALT cap as the engine applies it: MFS halving, 101% indexing, Schedule A line 5e worksheet

Used by: The SALT cap and its phase-down. Status: verified.

• 26 U.S. Code § 164 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall not exceed the applicable limitation amount (half the applicable limitation amount in the case of a married individual filing a separate return); 101 percent of the dollar amount in effect under this subparagraph for taxable years beginning in the preceding calendar year; (half the threshold amount in the case of a married individual filing a separate return)
• 2025 Instructions for Schedule A (Form 1040) (Internal Revenue Service; record) checked 2026-10-12
  Multiply line 6 by 30% (0.30); Enter the larger of the amount on line 8 or $10,000; half the amount on line 9 if married filing separately; If you elect to itemize for state tax or other purposes even though your itemized deductions are less than your standard deduction, check the box on line 18

MAGI = AGI (no §§911/931/933 exclusions in the engine). The statute states no rounding for the 101% steps; the engine does not round.

Itemize-vs-standard §63(b)/(e); MFS spouse-itemizes rule §63(c)(6)(A)

Used by: Interest you paid; Total itemized deductions; Itemize or take the standard deduction. Status: verified.

• 26 U.S. Code § 63 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Unless an individual makes an election under this subsection for the taxable year, no itemized deduction shall be allowed for the taxable year; a married individual filing a separate return where either spouse itemizes deductions
• Instructions for Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  will be less if you take the larger of your standard deduction or itemized deductions
• Instructions for Schedule A (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  your federal income tax will be less if you take the larger of your itemized deductions or your standard deduction

Engine 1.5.1 (PROP-FED-4): auto mode figures the return both ways when Schedule A has amounts and keeps the lower total tax (engine 1.5.1 kept the standard deduction on a tie; engine 1.5.2 takes the larger deduction on a tie, |difference| <= $0.005, as the 1040 and Schedule A instructions quoted above: line 15, which the capital-loss carryover worksheet and later years read, then follows the larger deduction). Engine <= 1.5.0 itemized when Schedule A (after §68) exceeded the standard deduction plus §170(p), on the premise that a larger deduction never raises the tax, which Form 8960 Part II (itemized returns only, engine 1.5.0) broke: $113,512 instead of $112,344 on the finding's return, and a $1,223.60 step on one cent of investment interest.

Charitable deduction limits §170(b)(1)(C)/(G)/(H) and the OBBBA 0.5% floor §170(b)(1)(I)

Used by: Gifts to charity: the percentage limits and the 0.5% floor. Status: verified.

• 26 U.S. Code § 170 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall not exceed 30 percent of the taxpayer's contribution base for such year; 60 percent of the taxpayer's contribution base for the taxable year, over (II) the aggregate amount of contributions taken into account under subparagraph (A) for such taxable year; the term "contribution base" means adjusted gross income (computed without regard to any net operating loss carryback to the taxable year under section 172); shall be allowed only to the extent that the aggregate of such contributions exceeds 0.5 percent of the taxpayer's contribution base for the taxable year; (ii) second, by taking into account charitable contributions to which subparagraph (C) applies to the extent thereof; (vi) sixth, by taking into account charitable contributions to which subparagraph (G) applies to the extent thereof; subparagraph (A) shall be applied by reducing (but not below zero) the contribution limitation allowed for the taxable year under such subparagraph by the aggregate contributions allowed under this subparagraph for such taxable year; shall be taken into account after all other charitable contributions
• Public Law 119-21 (One Big Beautiful Bill Act), enrolled text (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  SEC. 70425. 0.5 PERCENT FLOOR ON DEDUCTION OF CONTRIBUTIONS MADE BY INDIVIDUALS
• Publication 526 (2025), Charitable Contributions (Internal Revenue Service; record) checked 2026-10-12
  Enter your cash contributions to 50% limit organizations; Deductible amount. Enter the smaller of line 10 or line 12; Subtract line 27 from line 26; Deductible amount. Enter the smallest of line 8, 28, or 29

Carryovers (5 years) of contributions over the percentage limits, and of amounts disallowed by the floor, are not modelled: the excess is not deducted in the year (disclosed in federal_tax.c). Only cash and capital-gain property to public charities are modelled (no private-foundation 20%/30% classes). Engine 1.5.0 (FED-DIFF-01): the Worksheet 2 order — cash first under 60%, then property under the smallest of 30% and 50% minus the cash; engine <= 1.4.0 took the property first and gave the cash only what was left of 60%, never applying line 28.

Charitable contribution carryover: 5 succeeding years, current year first, oldest carryover first (IRC 170(d)(1)(A); Pub 526)

Used by: Gifts to charity: the five-year carryover. Status: verified.

• 26 U.S. Code § 170 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  such excess shall be treated as a charitable contribution described in subsection (b)(1)(A) paid in each of the 5 succeeding taxable years in order of time, but, with respect to any such succeeding taxable year, only to the extent of the lesser of the two following amounts:; the amount by which 50 percent of the taxpayer’s contribution base for such succeeding taxable year exceeds the sum of the charitable contributions described in subsection (b)(1)(A) payment of which is made by the taxpayer within such succeeding taxable year (determined without regard to this subparagraph) and the charitable contributions described in subsection (b)(1)(A) payment of which was made in taxable years before the contribution year which are treated under this subparagraph as having been paid in such succeeding taxable year; such excess shall be treated (in a manner consistent with the rules of subsection (d)(1)) as a charitable contribution to which clause (i) applies in each of the 5 succeeding years in order of time.; such excess shall be treated, in a manner consistent with the rules of subsection (d)(1), as a charitable contribution of capital gain property to which clause (i) applies in each of the 5 succeeding taxable years in order of time.; such excess shall be treated (in a manner consistent with the rules of subsection (d)(1)) as a charitable contribution (to which subparagraph (A) or (G) does not apply) in each of the 5 succeeding taxable years in order of time.
• Publication 526 (2025), Charitable Contributions (Internal Revenue Service; record) checked 2026-10-12
  You can carry over any contributions you can’t deduct in the current year because they exceed the limits based on your AGI. Except for qualified conservation contributions, you may be able to deduct the excess in each of the next 5 years until it is used up, but not beyond that time.; Generally, contributions you carry over are subject to the same percentage limits in the year to which they are carried as they were in the year of the contribution.; For each category of contributions, you deduct carryover contributions only after deducting all allowable contributions in that category for the current year. If you have carryovers from 2 or more prior years, use the carryover from the earlier year first.; A carryover of a contribution to a 50% limit organization must be used before contributions in the current year to organizations other than 50% limit organizations.; Don’t use this worksheet to figure the contributions you can deduct this year if you have a carryover of a charitable contribution from an earlier year.
• 2025 Instructions for Schedule A (Form 1040), Itemized Deductions (Internal Revenue Service; record) checked 2026-10-12
  You may have contributions that you couldn't deduct in an earlier year because they exceeded the limits on the amount you could deduct. In most cases, you have 5 years to use contributions that were limited in an earlier year.; After applying those limits, enter the amount of your carryover that you are allowed to deduct this year.

A carryover is consumed in a year the standard deduction is taken (26 CFR 1.170A-10(a)(2), (b)(2))

Used by: Gifts to charity: the five-year carryover. Status: verified.

• 26 CFR 1.170A-10: Charitable contributions carryovers of individuals (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The carryover provisions apply with respect to contributions made during a taxable year in excess of the applicable percentage limitation even though the taxpayer elects under section 144 to take the standard deduction in that year instead of itemizing the deduction allowable in computing taxable income for that year.; elects under section 144 to take the standard deduction instead of itemizing the deductions allowable in computing taxable income, there shall be treated as paid (but not allowable as a deduction) in such standard deduction year the lesser of the amounts determined under subdivisions (i) to (iii), inclusive, of this subparagraph.
• Publication 526 (2025), Charitable Contributions (Internal Revenue Service; record) checked 2026-10-12
  Claim the standard deduction in a carryover year

The reg text dates from the pre-1987 'section 144 election'; still the operative rule (Pub 526 lists 'Claim the standard deduction in a carryover year' as a special carryover situation it does not explain).

AGI-percentage limit classes (IRC 170(b)(1)(A),(B),(C),(D),(G); OBBBA made 60% cash permanent)

Used by: Gifts to charity: the five-year carryover. Status: verified.

• 26 U.S. Code § 170 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be allowed to the extent that the aggregate of such contributions does not exceed 50 percent of the taxpayer’s contribution base for the taxable year.; For taxable years beginning after December 31, 2017, any contribution of cash to an organization described in subparagraph (A) shall be allowed as a deduction under subsection (a) to the extent that the aggregate of such contributions does not exceed the excess of— (I) 60 percent of the taxpayer’s contribution base for the taxable year, over (II) the aggregate amount of contributions taken into account under subparagraph (A) for such taxable year.; Any charitable contribution other than a charitable contribution to which subparagraph (A) or (G) applies shall be allowed to the extent that the aggregate of such contributions does not exceed the lesser of— (i) 30 percent of the taxpayer’s contribution base for the taxable year, or (ii) the excess of 50 percent of the taxpayer’s contribution base for the taxable year over—; the total amount of contributions of such property which may be taken into account under subsection (a) for any taxable year shall not exceed 30 percent of the taxpayer’s contribution base for such year. For purposes of this subsection, contributions of capital gain property to which this subparagraph applies shall be taken into account after all other charitable contributions (other than charitable contributions to which subparagraph (D) applies).; (I) 20 percent of the taxpayer’s contribution base for the taxable year, or (II) the excess of 30 percent of the taxpayer’s contribution base for the taxable year over the amount of the contributions of capital gain property to which subparagraph (C) applies. For purposes of this subsection, contributions of capital gain property to which this subparagraph applies shall be taken into account after all other charitable contributions.
• Publication 526 (2025), Charitable Contributions (Internal Revenue Service; record) checked 2026-10-12
  1. Cash contributions subject to the limit based on 60% of AGI. Deduct the contributions that don’t exceed 60% of your AGI. 2. Noncash contributions (other than qualified conservation contributions) subject to the limit based on 50% of AGI. Deduct the contributions that don’t exceed 50% of your AGI minus your cash contributions to a 50% limit organization.

Cross-check of repo rule charity_limits (same 170 quotes re-confirmed). Cornell's (G)(i) now reads 'For taxable years beginning after December 31, 2017' with no end year - the 60% cash limit is permanent.

2026+: 0.5% floor and carryovers (IRC 170(b)(1)(I), 170(d)(1)(C), OBBBA 70425)

Used by: Gifts to charity: the five-year carryover. Status: verified.

• 26 U.S. Code § 170 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Any charitable contribution otherwise allowable (without regard to this subparagraph) as a deduction under this section shall be allowed only to the extent that the aggregate of such contributions exceeds 0.5 percent of the taxpayer’s contribution base for the taxable year.; (i) first, by taking into account charitable contributions to which subparagraph (D) applies to the extent thereof, (ii) second, by taking into account charitable contributions to which subparagraph (C) applies to the extent thereof, (iii) third, by taking into account charitable contributions to which subparagraph (B) applies to the extent thereof, (iv) fourth, by taking into account charitable contributions to which subparagraph (E) applies to the extent thereof, (v) fifth, by taking into account charitable contributions to which subparagraph (A) applies to the extent thereof, and (vi) sixth, by taking into account charitable contributions to which subparagraph (G) applies to the extent thereof.; Contributions disallowed by 0.5-percent floor carried forward only from years in which limitation is exceeded; In the case of any taxable year from which an excess is carried forward (determined without regard to this subparagraph) under any carryover rule, the applicable carryover rule shall be applied by increasing the excess determined under such applicable carryover rule for the contribution year (before the application of subparagraph (B)) by the amount attributable to the charitable contributions to which such rule applies which is not allowed as a deduction for the contribution year by reason of subsection (b)(1)(I).; the term “applicable carryover rule” means any carryover rule applicable to charitable contributions which were (in whole or in part) not allowed as a deduction for the contribution year by reason of subsection (b)(1)(I).
• Public Law 119-21 (One Big Beautiful Bill Act) (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  SEC. 70425. 0.5 PERCENT FLOOR ON DEDUCTION OF CONTRIBUTIONS MADE BY INDIVIDUALS
• Publication 505 (2026), Tax Withholding and Estimated Tax (Internal Revenue Service; record) checked 2026-10-12
  For 2026, if you plan to take an itemized deduction for a charitable contribution, you can only deduct charitable contributions that are more than 0.5% of your AGI.

The statute's text applies the floor to the aggregate of the year's contributions; no posted product says how a carryover into a later year is treated (Publication 526 for 2026 is not out). The engine applies the floor to the total, carryovers included, and discloses it; see NOTES.

2026+ 2/37 itemized-deduction reduction (IRC 68) vs carryovers

Used by: Gifts to charity: the five-year carryover. Status: verified.

• 26 U.S. Code § 68 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the amount of the itemized deductions otherwise allowable for the taxable year (determined without regard to this section) shall be reduced by 2⁄37 of the lesser of— (1) such amount of itemized deductions, or (2) so much of the taxable income of the taxpayer for the taxable year (determined without regard to this section and increased by such amount of itemized deductions) as exceeds the dollar amount at which the 37 percent rate bracket under section 1 begins with respect to the taxpayer.; This section shall be applied after the application of any other limitation on the allowance of any itemized deduction.

Cross-check of repo rule section_68. No text in 68 mentions carryovers; the carryover amount is fixed by 170(d) before 68 applies (68(b)).

§68 limitation on the tax benefit of itemized deductions (OBBBA §70111)

Used by: The §68 limitation on itemized deductions. Status: verified.

• 26 U.S. Code § 68 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be reduced by 2⁄37 of the lesser of- (1) such amount of itemized deductions, or (2) so much of the taxable income of the taxpayer for the taxable year (determined without regard to this section and increased by such amount of itemized deductions) as exceeds the dollar amount at which the 37 percent rate bracket under section 1 begins; This section shall be applied after the application of any other limitation on the allowance of any itemized deduction
• Public Law 119-21 (One Big Beautiful Bill Act), enrolled text (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  (c) <<NOTE: 26 USC 68 note.>> Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2025

Applies to ALL itemized deductions (not only charity): each itemized dollar in the 37% bracket saves 35 cents.

Non-itemizer charitable deduction §170(p) (OBBBA §70424)

Used by: Charitable deduction for non-itemizers. Status: verified.

• 26 U.S. Code § 170 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  if the individual does not elect to itemize deductions for such taxable year, the deduction under this section shall be equal to the deduction, not in excess of 1,000 ($2,000 in the case of a joint return); determined without regard to subsections (b)(1)(G)(ii), (b)(1)(I), and (d)(1); for the establishment of a new, or maintenance of an existing, donor advised fund
• 26 U.S. Code § 63 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  (4) the deduction provided in section 170(p)
• Public Law 119-21 (One Big Beautiful Bill Act), enrolled text (U.S. Government Publishing Office (govinfo); record) checked 2026-10-12
  SEC. 70424. PERMANENT AND EXPANDED REINSTATEMENT OF PARTIAL DEDUCTION FOR CHARITABLE CONTRIBUTIONS OF INDIVIDUALS WHO DO NOT ELECT TO ITEMIZE

A QSS return is not a joint return: $1,000.

Form 8606 pro-rata basis §408(d)(2)

Used by: Form 8606: the nontaxable part of a conversion; Form 8606: the nontaxable part of all distributions; Form 8606: basis carried forward. Status: verified.

• 26 U.S. Code § 408 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  all individual retirement plans shall be treated as 1 contract, (B) all distributions during any taxable year shall be treated as 1 distribution

Employer-plan dollars carry no after-tax basis in the engine. The 8606 line 10 ratio is not rounded to 3 places (the form allows 'at least 3 places').

Roth distributions §408A(d): qualified distribution, ordering, conversion 5-year recapture

Used by: Roth IRA distributions: ordering and the 5-year rules. Status: verified.

• 26 U.S. Code § 408A (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  made on or after the date on which the individual attains age 59½; within the 5-taxable year period beginning with the first taxable year for which the individual made a contribution to a Roth IRA; such distribution is made within the 5-taxable year period beginning with the taxable year in which such contribution was made, then section 72(t) shall be applied as if such portion were includible in gross income; Qualified rollover contributions to which paragraph (3) applies on a first-in, first-out basis; shall be allocated first to the portion of such contribution required to be included in gross income

Engine convention for 59½: END-OF-YEAR age >= 60 (the §72(t) convention). Death, first-home and special-purpose distributions are not modelled; an unknown first-contribution year is treated as not qualified.

§72(t)(2)(A) exceptions: disability, SEPP, separation from service at 55 (50 public safety), employer plans only; governmental 457(b) (engine 1.5.0); a beneficiary after the owner's death (engine 2.0.1)

Used by: Form 5329: early distributions; Form 5329: the exceptions to the additional tax; An inherited account: the year's required distribution. Status: verified.

• 26 U.S. Code § 72 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  made to a beneficiary (or to the estate of the employee) on or after the death of the employee; attributable to the employee's being disabled within the meaning of subsection (m)(7); part of a series of substantially equal periodic payments (not less frequently than annually); made to an employee after separation from service after attainment of age 55; Subparagraphs (A)(v) and (C) of paragraph (2) shall not apply to distributions from an individual retirement plan; unless the series of payments begins after the employee separates from service
• Retirement topics - Exceptions to tax on early distributions (Internal Revenue Service; record) checked 2026-10-12
  the employee separates from service during or after the year the employee reaches age 55 (age 50 for public safety employees

The SEPP schedule itself (RMD / amortization / annuitization methods, Notice 2022-6) is not computed: the caller supplies the installment. Other exceptions (first home, medical, birth/adoption, emergency, domestic abuse, terminal illness, ...) are not modelled. Engine 1.5.0: governmental457bDistribution is excepted at any age (rule gov_457b). Engine 1.5.0 (PROP-FED-2): the SEPP installment is IRA dollars. A series paid by an employer plan is excepted only once the employee has separated from service (§72(t)(3)(B), quoted above), which is not modelled: the API refuses a seppDistribution that overlaps employerPlanDistribution, and the engine limits the SEPP's taxable part to the taxable IRA part, so the Form 8606 ratio never reaches employer-plan dollars. Engine 2.0.1: beneficiaryDistribution (a beneficiary's distribution from an inherited IRA or employer plan, §72(t)(2)(A)(ii), quoted above; Form 5329 exception 04) is excepted at any age. The API refuses it with iraBasis: the decedent's basis in an inherited IRA is not pooled with the beneficiary's own (a separate Form 8606), which is not modelled.

Governmental §457(b) distributions are outside §72(t) (except amounts rolled in from a qualified plan)

Used by: Form 5329: the exceptions to the additional tax. Status: verified.

• 26 U.S. Code § 72 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  If any taxpayer receives any amount from a qualified retirement plan (as defined in section 4974(c)); attributable to an amount transferred to an eligible deferred compensation plan from a qualified retirement plan
• 26 U.S. Code § 4974 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  a plan described in section 401(a) which includes a trust exempt from tax under section 501(a); an individual retirement annuity described in section 408(b)
• Instructions for Form 5329 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Distributions from a section 457 plan, which aren't from a rollover from a qualified retirement plan

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect. §4974(c) lists §401(a), 403(a), 403(b) and 408(a)/(b) arrangements and no §457(b) plan; §72(t)(9) brings back only the part attributable to a rollover from a qualified plan, which the caller leaves out of governmental457bDistribution.

Missed-RMD excise §4974 (SECURE 2.0)

Used by: Form 5329: the missed-RMD excise tax. Status: verified.

• 26 U.S. Code § 4974 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  there is hereby imposed a tax equal to 25 percent of the amount by which such minimum required distribution exceeds the actual amount distributed during the taxable year; the first sentence of subsection (a) shall be applied by substituting "10 percent" for "25 percent"

The §4974(d) reasonable-cause waiver is not modelled. The excise is not part of the Form 2210 tax (i2210: Schedule 2 line 8 "additional tax on distributions only").

RMD Joint and Last Survivor Table (spouse sole beneficiary, more than 10 years younger)

Used by: The RMD divisor: Uniform Lifetime or Joint and Last Survivor; The required minimum distribution. Status: verified.

• 26 CFR 1.401(a)(9)-5 (eCFR (Office of the Federal Register / GPO); record) checked 2026-10-12
  If the employee's surviving spouse who is more than 10 years younger than the employee is the employee's sole beneficiary, then the applicable denominator is the joint and last survivor life expectancy for the employee and spouse
• 26 CFR 1.401(a)(9)-9 (eCFR (Office of the Federal Register / GPO); record) checked 2026-10-12
  The following table, referred to as the Joint and Last Survivor Table, is used for determining the joint and last survivor life expectancy of two individuals; 75 33.2 32.4 31.5 30.7 29.9 29.1 28.3 27.5 26.8 76; 73 33.4 32.6 31.7 30.9 30.1 29.4 28.6 27.9 27.2 74; 80 25.3 24.6 23.8 23.1 22.3 21.6 20.9 20.2 19.6 81

eCFR prints cell (19, 35) blank; the generator fills it from its mirror (35, 19) = 68.0 and says so in the header. The printed table is symmetric only to within its 0.1 rounding ((2,5) 88.5 vs (5,2) 88.6); lookups use [owner][spouse] as printed. --check re-derives the header from eCFR.

Uniform Lifetime Table (ages 72-120)

Used by: The RMD divisor: Uniform Lifetime or Joint and Last Survivor; The required minimum distribution. Status: verified.

• 26 CFR 1.401(a)(9)-9: Life expectancy and distribution period tables (eCFR (Office of the Federal Register); record) checked 2026-10-12
  Age of employee Applicable denominator 72 27.4 73 26.5 74 25.5 75 24.6 76 23.7; 117 2.7 118 2.5 119 2.3 120+ 2.0

All 49 rows machine-compared to the eCFR text: 0 differences.

SECURE 2.0 applicable age bands

Used by: The RMD divisor: Uniform Lifetime or Joint and Last Survivor. Status: verified.

• 26 CFR 1.401(a)(9)-2: Distributions commencing during an employee's lifetime (eCFR (Office of the Federal Register); record) checked 2026-10-12
  born on or after January 1, 1951, but before January 1, 1959, the applicable age is age 73; (v) [Reserved]; born on or after January 1, 1960, the applicable age is

1959 cohort = 73 is a disclosed assumption (reg reserved).

The RMD divides the account balance at the close of the preceding December 31

Used by: The required minimum distribution. Status: verified.

• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (Internal Revenue Service; record) checked 2026-10-12
  close of business on December 31 of the preceding year
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-12
  the account balance as of the last valuation date in the calendar year preceding that distribution calendar year

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect. Engine <= 1.4.0's planner divided the balance after the year's returns (fed-fm3-11).

First RMD may be delayed to April 1 of the next year (the RBD) -> two RMDs that year

Used by: The required minimum distribution. Status: verified.

• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The distribution required for the employee's first distribution calendar year (as described in paragraph (a)(2)(ii) of this section) may be made on or before April 1 of the following calendar year. The required minimum distribution for any other distribution calendar year (including the required minimum distribution for the distribution calendar year in which the employee's required beginning date occurs or the first distribution calendar year for the designated beneficiary) must be made on or before the end of that distribution calendar year.; If an employee's required beginning date is April 1 of the calendar year following the calendar year in which the employee attains the applicable age, then the employee's first distribution calendar year is the year the employee attains the applicable age.
• Retirement plan and IRA required minimum distributions FAQs (Internal Revenue Service; record) checked 2026-10-12
  You must take your first required minimum distribution for the year in which you reach age 73. However, you can delay taking the first RMD until April 1 of the following year. If you reach age 73 in 2024, you must take your first RMD by April 1, 2025, and the second RMD by Dec. 31, 2025.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  However, any amount distributed in the year you become age 73 will be credited toward the amount that must be distributed by April 1 of the following year.; The required minimum distribution for any year after the year you reach age 73 must be made by December 31 of that later year.
• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  The term “required beginning date” means April 1 of the calendar year following the later of— (I) the calendar year in which the employee attains the applicable age, or (II) the calendar year in which the employee retires.

Second-year RMD uses the Dec 31 balance of the first year, NOT reduced by the April-1 distribution

Used by: The required minimum distribution. Status: verified.

• Retirement plan and IRA required minimum distributions FAQs (Internal Revenue Service; record) checked 2026-10-12
  If you reach age 73 in 2024: Your first RMD is due by April 1, 2025, based on your account balance on December 31, 2023, and Your second RMD is due by December 31, 2025, based on your account balance on December 31, 2024.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  Distributions reduce the account balance in the year they are made. A distribution for last year made after December 31 of last year reduces the account balance for this year, but not for last year. Disregard distributions made after December 31 of last year in determining your required minimum distribution for this year.; The IRA account balance is the amount in the IRA at the end of the year preceding the year for which the required minimum distribution is being figured.
• 26 CFR 1.408-8: Distribution requirements for individual retirement plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  the account balance of the IRA as of December 31 of the calendar year preceding the calendar year for which distributions are required to be made is substituted for the account balance of the employee under; Except as provided in paragraph (d) of this section, no adjustments are made for contributions or distributions after that date.
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  the account balance as of the last valuation date in the calendar year preceding that distribution calendar year (valuation calendar year); The account balance is decreased by distributions made in the valuation calendar year after the valuation date.

Cross-check of repo rule rmd_prior_balance (same p590b / -5 quotes).

Inherited account: 10-year rule (SECURE Act, IRC 401(a)(9)(H))

Used by: An inherited account: the payout rule and the distribution period; An inherited account: the year's required distribution. Status: verified.

• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  10-year rule. Distributions satisfy this paragraph (c)(3) if the employee's entire interest is distributed by the end of the calendar year that includes the tenth anniversary of the date of the employee's death.; If the employee dies on or after the effective date of section 401(a)(9)(H) (as determined in
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  10-year limit for designated beneficiary who is not an eligible designated beneficiary. If the employee's designated beneficiary is not an eligible designated beneficiary (as determined in accordance with; then the calendar year described in this paragraph (e)(2) is the calendar year that includes the tenth anniversary of the date of the employee's death.
• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be applied by substituting “10 years” for “5 years”, and (II) shall apply whether or not distributions of the employee’s interests have begun in accordance with subparagraph (A).
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  The 10-year rule requires the IRA beneficiaries who are not taking life expectancy payments to withdraw the entire balance of the IRA by December 31 of the year containing the 10th anniversary of the owner’s death. For example, if the owner died in 2025, the beneficiary would have to fully distribute the IRA by December 31, 2035.; the beneficiary is a designated beneficiary who is not an eligible designated beneficiary, regardless of whether the owner died before reaching their required beginning date.; If the IRA owner dies before the required beginning date and the 10-year rule applies, no distribution is required for any year before the 10th year.; Don't use any of the tables if the owner died before their required beginning date and either the 5-year rule or the 10-year rule (discussed earlier) applies.

Statute: 401(a)(9)(H)(i) substitutes 10 years for the 5 years of 401(a)(9)(B)(ii) for designated beneficiaries; the 5-year rule remains for non-designated beneficiaries (estate, charity, non-see-through trust) when death is before the RBD.

Eligible designated beneficiary (EDB) categories (IRC 401(a)(9)(E)(ii); 26 CFR 1.401(a)(9)-4(e))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  The term “eligible designated beneficiary” means, with respect to any employee, any designated beneficiary who is— (I) the surviving spouse of the employee, (II) subject to clause (iii), a child of the employee who has not reached majority (within the meaning of subparagraph (F)), (III) disabled (within the meaning of section 72(m)(7)),; or (V) an individual not described in any of the preceding subclauses who is not more than 10 years younger than the employee.; The determination of whether a designated beneficiary is an eligible designated beneficiary shall be made as of the date of death of the employee.
• 26 CFR 1.401(a)(9)-4: Determination of the designated beneficiary (eCFR (Office of the Federal Register); record) checked 2026-10-07
  A designated beneficiary of the employee is an eligible designated beneficiary if, at the time of the employee's death, the designated beneficiary is; Determination of age of majority. An individual reaches the age of majority on the individual's 21st birthday.; Whether a designated beneficiary is not more than 10 years younger than the employee is determined based on the dates of birth of the employee and the beneficiary.; if the employee has more than one designated beneficiary, and at least one of those beneficiaries is not an eligible designated beneficiary, then the employee is treated as not having an eligible designated beneficiary.; Because B was not disabled as of the date of A's death, B ceases to be an eligible designated beneficiary upon reaching the age of majority in 2024
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  An IRA beneficiary is an eligible designated beneficiary if the beneficiary is the owner's surviving spouse, the owner's minor child, a disabled individual, a chronically ill individual, or any other individual who is not more than 10 years younger than the IRA owner.

Beneficiaries are fixed as of Sept 30 of the year after death (disclaimers/cash-outs by then remove a beneficiary): 1.401(a)(9)-4(c).

EDB life-expectancy payouts: start year and divisor (26 CFR 1.401(a)(9)-3(c)(4), -5(d)(2), -5(d)(3))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  Life expectancy payments. Distributions satisfy this paragraph (c)(4) if annual distributions that satisfy the requirements of; commence by the end of the calendar year following the calendar year in which the employee died, except as provided in paragraph (d) of this section (permitting a surviving spouse to delay the commencement of distributions).; Thus, a required minimum distribution is due for the calendar year of the eligible designated beneficiary's death, and that amount must be distributed during that calendar year to any beneficiary of the deceased eligible designated beneficiary to the extent it has not already been distributed to the eligible designated beneficiary.; If the employee has an eligible designated beneficiary, distributions must satisfy the life expectancy rule described in paragraph (c)(4) of this section.
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  the applicable denominator for distribution calendar years beginning with the first distribution calendar year for the designated beneficiary (as described in paragraph (a)(2)(iii) of this section) is the designated beneficiary's remaining life expectancy; For purposes of this paragraph (d), all life expectancies are determined using the Single Life Table in; If the designated beneficiary is not the employee's surviving spouse, then the designated beneficiary's remaining life expectancy is determined initially using the beneficiary's age as of the beneficiary's birthday in the calendar year following the calendar year of the employee's death.; for subsequent calendar years, the designated beneficiary's remaining life expectancy is determined by reducing that initial life expectancy by one for each calendar year that has elapsed after that first calendar year.; If the surviving spouse of the employee is the employee's sole beneficiary, then the surviving spouse's remaining life expectancy is redetermined each distribution calendar year up to and including the calendar year of the spouse's death using the surviving spouse's age as of the surviving spouse's birthday in the distribution calendar year.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  The terms of most IRAs require individual designated beneficiaries, who are eligible designated beneficiaries, to take required minimum distributions using the life expectancy rules (explained later) unless such beneficiaries elect to take distributions using the 10-year rule.; The deadline for making this election is the earlier of December 31 of the year the beneficiary must take the first required distribution, using their life expectancy or December 31 of the 10th anniversary for the 10-year rule.

Surviving-spouse beneficiary: delayed start, treat-as-own, rollover (26 CFR 1.401(a)(9)-3(d), 1.408-8(c); Pub 590-B)

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  If the employee's surviving spouse is the employee's sole beneficiary, then the commencement of distributions under paragraph (b)(3) or (c)(4) of this section may be delayed until the end of the calendar year in which the employee would have attained the applicable age.; are to be applied as if the surviving spouse were the employee. For this purpose, the date of death of the surviving spouse is substituted for the date of death of the employee.
• 26 CFR 1.408-8: Distribution requirements for individual retirement plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The surviving spouse of an individual may elect, in the manner described in paragraph (c)(2) of this section, to treat the surviving spouse's entire interest as a beneficiary in the individual's IRA (or the remaining part of that interest if distributions have begun) as the surviving spouse's own IRA.; In order to make the election described in this paragraph (c)(1), the surviving spouse must be the sole beneficiary of the IRA and have an unlimited right to withdraw amounts from the IRA.
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  then the first distribution calendar year for the designated beneficiary is the calendar year following the calendar year in which the employee died (or, if applicable, the calendar year described in; For purposes of this paragraph (d), all life expectancies are determined using the Single Life Table in
• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the date on which the distributions are required to begin under clause (iii)(III) shall not be earlier than the date on which the employee would have attained the applicable age
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If you inherit a traditional IRA from your spouse, you generally have the following two choices. 1. Treat it as your own IRA by designating yourself as the account owner; or 2. Treat it as your own by rolling it over into your IRA; You will be considered to have chosen to treat the IRA as your own if: • Contributions (including rollover contributions) are made to the inherited IRA, or • You don't take the required minimum distribution for a year as a beneficiary of the IRA.; You don't need to take any required minimum distributions until December 31 of 2030, the year your spouse would have reached age 73.; If you are the owner’s surviving spouse, then the applicable denominator continues to be determined each subsequent year using Table I . However, if you elect to treat the inherited IRA as your own, you will use Table III.

Death on/after the RBD: annual RMDs continue + longer-of divisor (26 CFR 1.401(a)(9)-5(d)(1), (d)(3)(ii))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The requirement to take an annual distribution in accordance with the preceding sentence continues to apply for every distribution calendar year until the employee's interest is fully distributed.; If section 401(a)(9)(H) applies to the employee's interest in the plan, then the distributions also must satisfy either section 401(a)(9)(B)(ii) (applied by substituting 10 years for 5 years); the applicable denominator is the greater of— (A) The designated beneficiary's remaining life expectancy; and (B) The employee's remaining life expectancy.; If the employee does not have a designated beneficiary as of the date determined under; the applicable denominator is the employee's remaining life expectancy.; The employee's remaining life expectancy is determined initially using the employee's age as of the employee's birthday in the calendar year of the employee's death. In subsequent calendar years, the remaining life expectancy is determined by reducing that initial life expectancy by one for each calendar year that has elapsed after that first calendar year.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If the owner died on or after their required beginning date (defined earlier) and you are a designated beneficiary, base your required minimum distributions for years after the year of the owner’s death on the longer of: • Your single life expectancy shown in Table I in Appendix B; or • The owner's life expectancy. If there is no designated beneficiary, use the owner's life expectancy.; In this case, use the owner’s life expectancy for their age as of the owner’s birthday in the year of death and reduce it by 1 for each subsequent year.

Minor-child EDB: life expectancy until 21, then 10 years (IRC 401(a)(9)(E)(iii); 26 CFR 1.401(a)(9)-5(e)(4))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall cease to be an eligible designated beneficiary as of the date the individual reaches majority and any remainder of the portion of the individual’s interest to which subparagraph (H)(ii) applies shall be distributed within 10 years after such date.
• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  10-year limit after minor child of the employee reaches age of majority. If the employee's designated beneficiary is an eligible designated beneficiary only because the beneficiary is the child of the employee who has not reached the age of majority at the time of the employee's death, then the calendar year described in this paragraph (e)(4) is the calendar year that includes the tenth anniversary of the date the designated beneficiary reaches the age of majority.; then the entire interest of the employee must be distributed by the end of the earliest of the calendar years described in paragraph (e)(2), (3), or (4) of this section.
• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The requirement to take an annual distribution in accordance with the preceding sentence continues to apply for all subsequent calendar years until the employee's interest is fully distributed.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  In either of those cases, the 10-year period ends on December 31 of the year containing the 10th anniversary of the eligible designated beneficiary's death or the child's attainment of majority.

Only the employee's OWN child (152(f)(1)) qualifies; a grandchild is not a minor-child EDB.

No designated beneficiary (estate, charity, non-see-through trust): 5-year rule / ghost life expectancy

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  If the employee does not have a designated beneficiary, as determined under; distributions must satisfy the 5-year rule described in paragraph (c)(2) of this section;; Distributions satisfy this paragraph (c)(2) if the employee's entire interest is distributed by the end of the calendar year that includes the fifth anniversary of the date of the employee's death.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  The 5-year rule applies to beneficiaries who are not designated beneficiaries if the owner died before their required beginning date (such as an estate or trust (but see Trust as beneficiary, later)).; You use the owner’s life expectancy to calculate required minimum distributions when the owner dies on or after the required beginning date and there is no designated beneficiary as of September 30 of the year following the year of the owner’s death.

Required beginning date (IRC 401(a)(9)(C); 26 CFR 1.408-8(b)(1))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  The term “required beginning date” means April 1 of the calendar year following the later of— (I) the calendar year in which the employee attains the applicable age, or (II) the calendar year in which the employee retires.
• 26 CFR 1.408-8: Distribution requirements for individual retirement plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  Thus, the IRA owner's required beginning date is April 1 of the calendar year following the calendar year in which the individual attains the applicable age.

Inherited Roth IRA: owner treated as dying before the RBD (IRC 408A(c)(4); 26 CFR 1.408-8(b)(1)(ii); 1.408A-6 Q&A-14)

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 U.S. Code § 408A (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the following provisions shall not apply to any Roth IRA: (A) Section 401(a)(9)(A).
• 26 CFR 1.408-8: Distribution requirements for individual retirement plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  No minimum distributions are required to be made from a Roth IRA while the owner is alive. After the Roth IRA owner dies, the required minimum distribution rules apply to the Roth IRA as though the Roth IRA owner died before his or her required beginning date.
• 26 CFR 1.408A-6: Distributions (eCFR (Office of the Federal Register); record) checked 2026-10-07
  The minimum distribution rules apply to the Roth IRA as though the Roth IRA owner died before his or her required beginning date.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If a Roth IRA owner dies, the minimum distribution rules that apply to traditional IRAs apply to Roth IRAs as though the Roth IRA owner died before their required beginning date.

The statutory cite is 408A(c)(4) ('Mandatory distribution rules not to apply before death'), not (c)(5) ((c)(5) is rollover contributions).

CARES Act 2203: 2020 disregarded in the 5-year rule (IRC 401(a)(9)(I)(iii)(II); 26 CFR 1.401(a)(9)-3(c)(2))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 U.S. Code § 401 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  if clause (ii) of subparagraph (B) applies, the 5-year period described in such clause shall be determined without regard to calendar year 2020.; The requirements of this paragraph shall not apply for calendar year 2020 to
• 26 CFR 1.401(a)(9)-3: Death before required beginning date (eCFR (Office of the Federal Register); record) checked 2026-10-07
  For purposes of this paragraph (c)(2), if an employee died before January 1, 2020, then the 2020 calendar year is disregarded when determining the calendar year that includes the fifth anniversary of the date of the employee's death.; For example, if an employee dies on any day in 2022, the entire interest must be distributed by the end of 2027 in order to satisfy the 5-year rule in section 401(a)(9)(B)(ii).

The statute's text is not limited to pre-2020 deaths, but the reg (-3(c)(2)) is; follow the reg. Also 401(a)(9)(I)(i): no RMDs at all for calendar 2020 (2020 waiver) - affects only 2020 history.

Single Life Table (ages 0-120)

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-9: Life expectancy and distribution period tables (eCFR (Office of the Federal Register); record) checked 2026-10-12
  Age Life expectancy 0 84.6 1 83.7 2 82.8; 55 31.6 56 30.6 57 29.8; 117 1.6 118 1.4 119 1.1 120+ 1.0

Federal engine 2.2: the engine carries the table (rmd.c) for the inherited-account RMDs; the website reads it from the generated config. All 121 rows machine-compared to the eCFR text: 0 differences.

2022 Single Life Table reset for pre-2022 deaths (26 CFR 1.401(a)(9)-9(f)(2))

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• 26 CFR 1.401(a)(9)-9: Life expectancy and distribution period tables (eCFR (Office of the Federal Register); record) checked 2026-10-07
  If an employee died before January 1, 2022, and, under the rules of; the applicable denominator for a distribution calendar year beginning on or after January 1, 2022, is determined by using the Single Life Table in paragraph (b) of this section to determine the initial life expectancy for the age of the relevant individual in the relevant calendar year and then reducing the resulting applicable denominator by 1 for each subsequent year.; then the applicable denominator would be 12.1 years (the 14.1-year life expectancy for a 76-year-old under the Single Life Table in paragraph (b) of this section, reduced by 2 years).

Applies to spouse too when the spouse died before 2022 (spouse's death-year LE reset).

Death after reaching RMD age but before the April-1 RBD: no RMD for the death year

Used by: An inherited account: the payout rule and the distribution period. Status: verified.

• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If an IRA owner dies after reaching age 73, but before the IRA owner's required beginning date, no minimum distribution is required for that year because death occurred before the required beginning date.
• 26 CFR 1.401(a)(9)-2: Distributions commencing during an employee's lifetime (eCFR (Office of the Federal Register); record) checked 2026-10-07
  distributions to the employee are not treated as having begun in accordance with section 401(a)(9)(A)(ii) until the employee's required beginning date; Thus, even if payments have been made before the employee's required beginning date, the rules of § 1.401(a)(9)-3 will apply if the employee dies before that date.

Planner relevance: delaying the first RMD to April 1 changes the heirs' regime if death occurs in that window.

RMD for the year of the owner's death

Used by: An inherited account: the year's required distribution. Status: verified.

• 26 CFR 1.401(a)(9)-5: Required minimum distributions from defined contribution plans (eCFR (Office of the Federal Register); record) checked 2026-10-07
  Thus, a required minimum distribution is due for the calendar year of the employee's death, and that amount must be distributed during that year to any beneficiary to the extent it has not already been distributed to the employee.
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If the owner died before the required beginning date, there is no required minimum distribution in the year of the owner's death.; If the owner died on or after the required beginning date, the IRA beneficiaries are responsible for figuring and distributing the owner's required minimum distribution in the year of death.; If an IRA owner dies after reaching age 73, but before the IRA owner's required beginning date, no minimum distribution is required for that year because death occurred before the required beginning date.

No 4974 excise for 'specified RMDs' 2021-2024 (Notices 2022-53, 2023-54, 2024-35); final regs from 2025

Used by: An inherited account: the year's required distribution. Status: verified.

• Notice 2022-53: Certain Required Minimum Distributions for 2021 and 2022 (Internal Revenue Service; record) checked 2026-10-12
  the IRS will not assert that an excise tax is due under section 4974.; would be required to be made pursuant to section 401(a)(9) in 2021 or 2022 under a defined contribution plan or IRA; the employee (or IRA owner) died in 2020 or 2021 and on or after the employee’s (or IRA owner’s) required beginning date, and (2) the designated beneficiary is not taking lifetime or life expectancy payments pursuant to section 401(a)(9)(B)(iii);; the eligible designated beneficiary died in 2020 or 2021, and (2) that eligible designated beneficiary was taking lifetime or life expectancy payments pursuant to section 401(a)(9)(B)(iii) of the Code.
• Notice 2023-54: Transition relief and guidance relating to certain RMDs (2023) (Internal Revenue Service; record) checked 2026-10-12
  the IRS will not assert that an excise tax is due under § 4974.; would be required to be made pursuant to § 401(a)(9) in 2023 under a defined contribution plan or IRA
• Notice 2024-35: Certain Required Minimum Distributions for 2024 (Internal Revenue Service; record) checked 2026-10-12
  To the extent a taxpayer did not take a specified RMD (as defined in section IV.C of this notice), the IRS will not assert that an excise tax is due under § 4974.; would be required to be made pursuant to § 401(a)(9) in 2024 under a defined contribution plan or IRA that is subject to the rules of § 401(a)(9)(H); the employee (or IRA owner) died in 2020, 2021, 2022, or 2023, and on or after the employee’s (or IRA owner’s) required beginning date, and (2) the designated beneficiary is not using the lifetime or life expectancy payments exception under § 401(a)(9)(B)(iii);; a beneficiary of an eligible designated beneficiary (including a designated beneficiary who is treated as an eligible designated beneficiary pursuant to § 401(b)(5) of the SECURE Act) if: (1) the eligible designated beneficiary died in 2020, 2021, 2022, or 2023, and (2) that eligible designated beneficiary was using the lifetime or life expectancy payments exception under § 401(a)(9)(B)(iii) of the Code.; Final regulations regarding RMDs under § 401(a)(9) and related provisions are anticipated to apply for determining RMDs for calendar years beginning on or after January 1, 2025.

Notice 2024-35 itself says 'anticipated'; the final regs (T.D. 10001, 89 FR 58907, July 19, 2024) are the ones in eCFR today (amendment note quoted in the -3/-5 sources).

4974 excise on a missed inherited RMD (cross-check of repo rule missed_rmd_4974)

Used by: An inherited account: the year's required distribution. Status: verified.

• 26 U.S. Code § 4974 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  there is hereby imposed a tax equal to 25 percent of the amount by which such minimum required distribution exceeds the actual amount distributed during the taxable year; the first sentence of subsection (a) shall be applied by substituting "10 percent" for "25 percent"
• Publication 590-B (2025), Distributions from Individual Retirement Arrangements (IRAs) (Internal Revenue Service; record) checked 2026-10-12
  If the 10-year rule applies, the amount remaining in the IRA, if any, after December 31 of the year containing the 10th anniversary of the owner's death is subject to the excise tax detailed in Excess Accumulations (Insufficient Distributions), later.

Estimated-tax safe harbours §6654(d)/(e) + Form 2210 regular-method penalty

Used by: Form 2210: the required annual payment. Status: verified.

• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  exceeds $150,000, clause (ii) of subparagraph (B) shall be applied by substituting "110 percent" for "100 percent"; shall be applied by substituting "$75,000" for "$150,000"; reduced by the credit allowable under section 31, is less than $1,000

Modelled: see rule estimated_2210.

Form 2210 regular-method penalty: withholding split, period of underpayment, per-installment penalty

Used by: Form 2210: the required annual payment; Form 2210: the underpayment by installment; Form 2210: the penalty. Status: verified.

• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  an equal part of such amount shall be deemed paid on each due date; the 15th day of the 4th month following the close of the taxable year
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  The penalty is figured separately for each installment due date; substitute 110% for 100% in (2) above; Line 8 (additional tax on distributions only)

The underpayment calculator computes through the JS module, the JS copy of federal_est_compute (drift gate EST-module / EST-page). The annualized income method (Schedule AI), §6654(e)(3) waivers and the farmer/fisher 66⅔% rule are not modelled (stated on the page).

Form 2210 Schedule AI: annualization periods and factors

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  1/1/25–3/31/25 1/1/25–5/31/25 1/1/25–8/31/25 1/1/25–12/31/25; 2 Annualization amounts. (Estates and trusts, see instructions.) 2 4 2.4 1.5 1 3 Annualized income. Multiply line 1 by line 2
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Period (a) includes items for January 1 through March 31. • Period (b) includes items for January 1 through May 31. • Period (c) includes items for January 1 through August 31. • Period (d) includes items for the entire year.; For each period (column), figure your total income minus your adjustments to income. Include your share of partnership or S corporation income or loss items for the period. If you’re self-employed, be sure to take into account the deductible part of your self-employment tax.; Instead, use 6, 3, 1.71429, and 1.09091, respectively, as the annualization amounts.
• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  computed by placing on an annualized basis the taxable income, alternative minimum taxable income, and adjusted self-employment income for months in the taxable year ending before the due date for the installment

Schedule AI lines 4-13: deductions

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  If you itemize, enter itemized deductions for the period shown in each column. All others, enter -0-, and skip to line 7.; 5 Annualization amounts . . . . . . . . . . 5 4 2.4 1.5 1 6 Multiply line 4 by line 5; In each column, enter the amount of your standard deduction from Form 1040 or 1040-SR.; Enter the larger of line 6 or line 7; Deduction for qualified business income.; Form 1040, 1040-SR, or 1040-NR filers, enter -0- in each column.
• Form 2210 (2026) early-release DRAFT (Internal Revenue Service; record) checked 2026-10-12
  9b Additional deductions (see instructions); 10 Add lines 8, 9a, and 9b

The 2026 draft (f2210--dft.pdf) adds line 9b 'Additional deductions'; its instructions are not yet out - presumably the Schedule 1-A deductions (seniors, tips, overtime, car-loan interest). Re-check when i2210 (2026) posts.

Schedule AI lines 14-21: tax, SE tax, other taxes, credits, applicable percentage

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  14 Figure your tax on the amount on line 13. See instructions; Enter other taxes for each payment period including, if applicable, Additional Medicare Tax and/or Net Investment Income Tax. See instructions; 20 Applicable percentage . . . . . . . . . . 20 22.5% 45% 67.5% 90% 21 Multiply line 19 by line 20
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Enter all of the other taxes you owed because of events that occurred during the months shown in the column headings.; plus the tax from Form 4972, Tax on Lump-Sum Distributions; Form 8814, Parents’ Election To Report Child’s Interest and Dividends; and any alternative minimum tax (AMT).; Figure alternative minimum taxable income based on your income and deductions during the periods shown in the column headings. Multiply this amount by the annualization amounts shown for each column on Schedule AI, line 2, before subtracting the AMT exemption.; When figuring your credits, annualize any item of income or deduction used to figure each credit.; Any Additional Medicare Tax on self-employment income will be computed in Part I.
• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  1st 22.5 2nd 45 3rd 67.5 4th 90.

NIIT / Additional Medicare: neither the form nor i2210 states an annualization factor for them (only AMT is explicitly annualized); 'taxes you owed because of events that occurred during the months' - see NOTES.

Schedule AI Part II: annualized SE tax (2025 and 2026 draft)

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  29 Prorated social security tax limit . . . . . . . 29 $44,025 $73,375 $117,400 $176,100; 32 Annualization amounts . . . . . . . . . . 32 0.496 0.2976 0.186 0.124 33 Multiply line 32 by the smaller of line 28 or line 31; 34 Annualization amounts . . . . . . . . . . 34 0.116 0.0696 0.0435 0.029 35 Multiply line 28 by line 34; Enter actual wages for the period subject to social security tax
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Generally, to figure your net earnings from self-employment on line 28, multiply your net profit from all trades or businesses for each period by 92.35% (0.9235). If your self-employment income for the applicable periods is less than $400, enter zero in Part II, line 28.
• Form 2210 (2026) early-release DRAFT (Internal Revenue Service; record) checked 2026-10-12
  $46,125 $76,875 $123,000 $184,500 0.496 0.2976 0.186 0.124 0.116 0.0696 0.0435 0.029

Schedule AI lines 22-27: required installment = smaller of annualized and regular (+ recapture)

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  22 Enter the total of the amounts in all previous columns of line 27 22 23 Subtract line 22 from line 21. If zero or less, enter -0- 23 24 Enter 25% (0.25) of line 9 on page 1 of Form 2210 in each column 24 25 Subtract line 27 of the previous column from line 26 of that column 25 26 Add lines 24 and 25 . . . . . . . . . . . 26 27 Enter the smaller of line 23 or line 26 here and on Form 2210, Part III, line 10; Required installments. If box C in Part II applies, enter the amounts from Schedule AI, line 27. Otherwise, enter 25% (0.25) of line 9, Form 2210, in each column.
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  To figure the amount of each required installment, Schedule AI selects the smaller of the annualized income installment or the regular installment (that has been increased by the amount saved by using the annualized income installment method in figuring any earlier installments).
• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  if the individual establishes that the annualized income installment is less than the amount determined under paragraph (1)— (i) the amount of such required installment shall be the annualized income installment, and (ii) any reduction in a required installment resulting from the application of this subparagraph shall be recaptured by increasing the amount of the next required installment determined under paragraph (1) by the amount of such reduction (and by increasing subsequent required installments to the extent that the reduction has not previously been recaptured under this clause).; the annualized income installment is the excess (if any) of— (i) an amount equal to the applicable percentage of the tax for the taxable year computed by placing on an annualized basis

Using Schedule AI: box C, all due dates, attach the form

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  C Your income varied during the year and your penalty is reduced or eliminated when figured using the annualized income installment method. You must figure the penalty using Schedule Al and file Form 2210.
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  If you use Schedule AI for any payment due date, you must use it for all payment due dates.; Check box C in Part II.; Attach Form 2210, Parts I, II, III, and Schedule AI to your return.; If you use the cash method of accounting (used by most people), include all income actually or constructively received during the period and all deductions actually paid during the period.

Withholding is deemed paid in equal parts on the 4 due dates unless actual dates are elected (box D)

Used by: Form 2210 Schedule AI: the annualized income installment method. Status: verified.

• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  you are considered to have paid one-fourth of these amounts on each payment due date unless you can show otherwise.; If you treat withholding as paid on the dates it was actually withheld for estimated tax purposes, you must check box D
• Form 2210 (2025), Underpayment of Estimated Tax by Individuals, Estates, and Trusts (Internal Revenue Service; record) checked 2026-10-12
  D Your penalty is lower when figured by treating the federal income tax withheld from your income as paid on the dates it was actually withheld, instead of in equal amounts on the payment due dates.
• 26 U.S. Code § 6654 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  an equal part of such amount shall be deemed paid on each due date for such taxable year, unless the taxpayer establishes the dates on which all amounts were actually withheld, in which case the amounts so withheld shall be deemed payments of estimated tax on the dates on which such amounts were actually withheld.; (A) wage withholding, and (B) all other amounts withheld for which credit is allowed under section 31.

Form 1040 lines 2b/3a/3b, Schedule D lines 6/14, Form 8960 line 8 (fed2/w3a trace line labels)

Used by: Taxable interest (line 2b); Ordinary dividends (line 3b); Qualified dividends (line 3a); Short-term capital loss carryover in (Schedule D line 6); Long-term capital loss carryover in (Schedule D line 14); Total investment income (Form 8960 line 8). Status: verified.

• Form 1040 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Taxable interest; Qualified dividends; Ordinary dividends
• Schedule D (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  Short-term capital loss carryover. Enter the amount, if any, from line 8 of your Capital Loss Carryover Worksheet; Long-term capital loss carryover. Enter the amount, if any, from line 13 of your Capital Loss Carryover Worksheet
• Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Total investment income

fed2/w3a (R1/R2).

Schedule D line 21 ($3,000 / $1,500 limit applied) and the §1212(b) capital loss carryover (short-term / long-term), Capital Loss Carryover Worksheet

Used by: Short-term capital loss carryover in (Schedule D line 6); Long-term capital loss carryover in (Schedule D line 14); Capital loss allowed (Schedule D line 21); Short-term capital loss carryover to next year; Long-term capital loss carryover to next year. Status: verified.

• Schedule D (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  If line 16 is a loss, enter here and on Form 1040, 1040-SR, or 1040-NR, line 7a, the smaller of: • The loss on line 16; or • ($3,000), or if married filing separately, ($1,500)
• 26 U.S. Code § 1212 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the excess of the net short-term capital loss over the net long-term capital gain for such year shall be a short-term capital loss in the succeeding taxable year; the excess of the net long-term capital loss over the net short-term capital gain for such year shall be a long-term capital loss in the succeeding taxable year; the term "adjusted taxable income" means taxable income increased by the sum of
• Instructions for Schedule D (Form 1040) 2025 (Internal Revenue Service; record) checked 2026-10-12
  If the amount would have been a loss if you could enter a negative number on that line, enclose the amount in parentheses; Enter the smaller of line 2 or line 3; Short-term capital loss carryover for 2025. Subtract line 7 from line 5; Long-term capital loss carryover for 2025. Subtract line 12 from line 9
• Publication 550, Investment Income and Expenses (Internal Revenue Service; record) checked 2026-10-12
  Use short-term losses first
• Publication 550, Investment Income and Expenses (Internal Revenue Service; record) checked 2026-10-12
  can be deducted only on the final income tax return filed for the decedent; The decedent's estate cannot deduct any of the loss or carry it over to following years; can be deducted only on the return of the spouse who actually had the loss

fed2/w3a (R2), opt-in (API capitalLossRules / capitalLossCarryoverShortTerm / capitalLossCarryoverLongTerm). State returns: each state's own capital-loss rule (state engine 1.9.0, /docs/state-tax/). Engine 1.4.0: in the year the spouse dies (the final joint return) the Monte Carlo planner carries forward only the survivor's share of the carryover out (IRS Pub 550, 'Decedent's capital loss'); the spouse's share of the household's losses is spouseCapitalLossShare, default 0.5 (a jointly owned account). POST /api/federal-tax prices one return: its carryover out is that return's, and the caller enters next year's survivor carryover.

Form 8960 line 3: annuities that are not from a §401/403/408/457(b) plan are net investment income

Used by: Net investment income: nonqualified annuities (Form 8960 line 3). Status: verified.

• Instructions for Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Enter the gross income from all annuities, except annuities paid from the following
• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  gross income from interest, dividends, annuities, royalties, and rents; shall not include any distribution from a plan or arrangement described in section 401(a), 403(a), 403(b), 408, 408A, or 457(b)
• Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Annuities (see instructions)

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect.

§72(q) 10% additional tax on a nonqualified annuity's taxable payments before 59½, and its exceptions (Form 5329 Part I)

Used by: Net investment income: nonqualified annuities (Form 8960 line 3); §72(q): the 10% on a nonqualified annuity before 59½; §72(q)(2): the annuity's exceptions. Status: verified.

• 26 U.S. Code § 72 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  If any taxpayer receives any amount under an annuity contract; made on or after the death of the holder; attributable to the taxpayer’s becoming disabled within the meaning of subsection (m)(7); allocable to investment in the contract before August 14, 1982; under a qualified funding asset (within the meaning of section 130(d); under an immediate annuity contract (within the meaning of section 72(u)(4)); which is purchased by an employer upon the termination of a plan described in section 401(a) or 403(a); plus interest for the deferral period
• Publication 575, Pension and Annuity Income (2025) (Internal Revenue Service; record) checked 2026-10-12
  If you must pay either of these taxes, report them on; From an immediate annuity contract (a single premium; 5% rate on certain early distributions from deferred
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  Distributions from annuity contracts to the extent that the

Federal engine 2.3 (B3): replaces the API's refusal of nonqualifiedAnnuity before 59½. The exceptions of §72(q)(2)(B) (after the holder's death), (D) (substantially equal periodic payments) and (F), (G), (I), (J) (investment before August 14, 1982, a qualified funding asset, an immediate annuity, an annuity bought by an employer on a plan's termination) are the caller's parts of the taxable amount; (A) 59½ is the age clock of rule 72t, (C) disability the disabled input. Not modelled: the §72(q)(3) recapture with interest of a modified series of payments, the 5% rate under a pre-March 1, 1986 election, a modified endowment contract (§72(v)).

Form 8960 Part II: deductions properly allocable to net investment income (§1411(c)(1)(B))

Used by: Form 8960 line 9a: investment interest; Form 8960 line 9b: state income tax allocable to net investment income; Form 8960 line 12: net investment income. Status: verified.

• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the deductions allowed by this subtitle which are properly allocable to such gross income
• Instructions for Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  interest expense you paid or accrued during the tax year deducted on Schedule A; Include state, local, and foreign income taxes you paid for the tax year that are attributable to NII; you may use any reasonable method to determine that portion of the deduction; an allocation of the deduction based on the ratio of the amount of a taxpayer's gross investment income (Form 8960, line 8) to the amount of the taxpayer's AGI; Sales taxes aren't deductible in computing NII; if properly deducted on your return; Total tax deductions may be limited under section 164(b)(6)
• Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Investment interest expenses; State, local, and foreign income tax; Subtract Part II, line 11, from Part I, line 8
• 26 CFR 1.1411-4: Definition of net investment income (eCFR (Office of the Federal Register); record) checked 2026-10-12
  Investment interest (as defined in section 163(d)(3)) to the extent allowed under section 163(d)(1); may be determined by taxpayers using any reasonable method; are allowed in determining net investment income only to the extent the items are deductible; The amount of itemized deductions allowed in determining net investment income after applying sections 67 and 68 is the lesser of; The total amount of itemized deductions allowed after the application of sections 67 and 68

Added 2026-09-28 (fed6/f1, engine 1.5.0); every quote checked with scripts/check_state_tax_sources.py --url/--expect. Not modelled on line 9b: foreign income tax (Schedule A line 6) and real or personal property taxes attributable to NII; line 9c, line 10 and Form 4952 (investmentInterest is the deductible amount the caller gives). With the 2026+ §68 reduction, lines 9a and 9b together are at most the itemized deductions allowed after §68 (Reg. §1.1411-4(f)(7)(ii), the lesser of the two), scaled together when the cap binds.

The cost-of-living adjustment of later tax years (26 U.S.C. 1(f)(3)-(7), 1(j)(3)(B), 63(c)(7)(B)(ii), 55(d)(4)(B), 199A(e)(2)(B), 408(d)(8)(G))

Used by: One amount in a later year; The year's brackets and deductions; The QCD limits in a later year. Status: verified.

• 26 U.S.C. 1 (Legal Information Institute (U.S. Code text); record) checked 2026-10-12
  the c-cpi-u for any calendar year is the average of the c-cpi-u as of the close of the 12-month period ending on august 31 of such calendar year; if any increase determined under paragraph (2)(a), section 63(c)(4), section 68(b)(2) [1] or section 151(d)(4) is not a multiple of $50, such increase shall be rounded to the next lowest multiple of $50; shall be applied by substituting "$25" for "$50" each place it appears; solely for purposes of determining the dollar amounts at which any rate bracket higher than 12 percent ends and at which any rate bracket higher than 22 percent begins
• 26 U.S.C. 63 (Legal Information Institute (U.S. Code text); record) checked 2026-10-12
  determined by substituting "2024" for "2016" in subparagraph (a)(ii) thereof. if any increase under this clause is not a multiple of $50, such increase shall be rounded to the next lowest multiple of $50; "calendar year 1987" in the case of the dollar amounts contained in paragraph (2)(b), (2)(c), or (5)(a) or subsection (f)

Every amount, its base year and base amount, and the index levels are in research/data/federal-tax-indexing.json (checked weekly with the other provenance).

IRMAA income floors in later years (42 U.S.C. 1395r(i)(5))

Used by: The IRMAA income floors in a later year. Status: verified.

• 42 U.S.C. 1395r (Legal Information Institute (U.S. Code text); record) checked 2026-10-12
  if any dollar amount after being increased under subparagraph (a) or (c) is not a multiple of $1,000, such dollar amount shall be rounded to the nearest multiple of $1,000; (or, in the case of a calendar year beginning with 2020, august 2018); subparagraph (a) shall not apply with respect to each dollar amount in paragraph (3) of $500,000; in the case of any calendar year beginning after 2027, each dollar amount in paragraph (3) of $500,000 shall be increased

The amounts and base amounts are in research/data/federal-tax-indexing.json rule fed-irmaa-floors.

IRMAA 2026 Part B tiers (single/MFJ)

Used by: The IRMAA income floors in a later year. Status: verified.

• 2026 Medicare Parts A & B Premiums and Deductibles (Centers for Medicare & Medicaid Services; record) checked 2026-10-12
  Less than or equal to $109,000 Less than or equal to $218,000 $0.00 $202.90; Greater than $109,000 and less than or equal to $137,000 Greater than $218,000 and less than or equal to $274,000 $81.20 $284.10; Greater than $137,000 and less than or equal to $171,000 Greater than $274,000 and less than or equal to $342,000 $202.90 $405.80; Greater than $171,000 and less than or equal to $205,000 Greater than $342,000 and less than or equal to $410,000 $324.60 $527.50; Greater than $205,000 and less than $500,000 Greater than $410,000 and less than $750,000 $446.30 $649.20; Greater than or equal to $500,000 Greater than or equal to $750,000 $487.00 $689.90

QCD limit 2026 §408(d)(8)

Used by: The QCD limits in a later year. Status: verified.

• Notice 2025-67: 2026 retirement plan limitations (Internal Revenue Service; record) checked 2026-10-12
  under section 408(d)(8)(A) is increased from $108,000 to $111,000; pursuant to a one-time election is increased from $54,000 to $55,000

Source is Notice 2025-67 (not Rev. Proc. 2025-32).

Form 8962 (premium tax credit): lines 1-29, the annual (line 11) and monthly (lines 12-23) calculation, the line 5 percentage with its decimals dropped, lines 8a/8b rounded to the dollar, line 24 the lesser of the premium and the SLCSP premium less the contribution

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• Instructions for Form 8962 (2025), Premium Tax Credit (Internal Revenue Service; record) checked 2026-10-12
  drop any numbers after the decimal point; Multiply line 3 by line 7 and enter the result on line 8a, rounded to the nearest whole dollar amount; Divide line 8a by 12.0 and enter the result on line 8b, rounded to the nearest whole dollar amount; Subtract the amount in column (c) from the amount in column (b). If the result is zero or less, enter -0-; Enter the lesser of the amount in column (a) or the amount in column (d); You were enrolled in the qualified health plan for all 12 months during 2025; Your SLCSP premium is the same for every month of 2025
• Form 8962 (2025), Premium Tax Credit (PTC) (Internal Revenue Service; record) checked 2026-10-12
  Excess advance PTC repayment. Enter the smaller of line 27 or line 28 here and on Schedule 2 (Form 1040), line 1a; Net PTC. If line 24 is greater than line 25, subtract line 25 from line 24
• 26 U.S. Code § 36B (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the premium assistance amount determined under this subsection with respect to any coverage month is the amount equal to the lesser of; an amount equal to 1/12 of the product of the applicable percentage and the taxpayer; the most recently published poverty line as of the 1st day of the regular enrollment period

Federal engine 2.3 (B1). The TY2026 Form 8962 is not published; the TY2025 instructions' mechanics with the 2026 law (Rev. Proc. 2025-25 percentages, no repayment limitation, the 400% limit). The ACA bridge's subsidy is this function's line 24 (aca_bridge_optimizer.c healthcare_cost_core). Every quote checked 2026-10-08 with scripts/check_state_tax_sources.py --url/--expect.

The applicable percentage within an income tier: linear, rounded to the nearest one-hundredth of one percent (Form 8962 line 7, Table 2)

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• 26 CFR 1.36B-3, Computing the premium assistance credit amount (eCFR (National Archives); record) checked 2026-10-12
  increases on a sliding scale in a linear manner and is rounded to the nearest one-hundredth of one percent

The 2025 instructions' Table 2 (the enhanced 0%-8.5% schedule) follows the same rule: line 5 = 301 gives 0.0603 (6.025% rounded half up).

Who is an applicable taxpayer in 2026: household income 100%-400% of the poverty line; below 100% only under 26 CFR 1.36B-2(b)(6); married taxpayers file jointly (the 1.36B-2(b)(2) exception); the household income (modified AGI) definition

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• 26 U.S. Code § 36B (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  equals or exceeds 100 percent but does not exceed 400 percent of an amount equal to the poverty line; any amount of interest received or accrued by the taxpayer during the taxable year which is exempt from tax; the taxpayer shall be treated as an applicable taxpayer only if the taxpayer and the taxpayer
• 26 CFR 1.36B-2, Eligibility for premium tax credit (eCFR (National Archives); record) checked 2026-10-12
  is less than 100 percent of the Federal poverty line for the taxpayer's family size is treated as an applicable taxpayer for the taxable year if; Victims of domestic abuse and abandonment

The below-100% rule for lawfully present aliens (§36B(c)(1)(B)) was repealed for taxable years beginning after 2025 (P.L. 119-21 §71302): the API has no input for it. Eligibility for other minimum essential coverage, affordability of employer coverage, the dependency facts and the special enrollment period rule (§71304) are the caller's assertion.

ACA applicable percentage table 2026

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• Rev. Proc. 2025-25: 2026 applicable percentage table (§36B) and required contribution percentage (Internal Revenue Service; record) checked 2026-10-12
  Less than 133% At least 133% but less than 150% At least 150% but less than 200% At least 200% but less than 250% At least 250% but less than 300% At least 300% but not more than 400%; Initial percentage Final percentage 2.10% 3.14% 4.19% 6.60% 8.44% 9.96% 2.10% 4.19% 6.60% 8.44% 9.96% 9.96%

Rev. Proc. 2025-25 §3.01. 2.10% applies below 133% FPL only; 3.14%-4.19% across 133-150%. The aca_bridge_optimizer.c header comment said '2.10% at <=150%' (code was right); corrected 2026-09-28. Federal engine 2.3: the table moved from aca_bridge_optimizer.c applicable_pct() (continuous, unrounded) to the federal engine's Form 8962; the bridge and the return share it.

2025 HHS poverty guidelines (used for 2026 coverage), 48+DC

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• Annual Update of the HHS Poverty Guidelines (90 FR 5917, 2025-01-17) (Department of Health and Human Services (Federal Register); record) checked 2026-10-12
  Persons in family/household Poverty guideline 1 $15,650 2 21,150 3 26,650 4 32,150 5 37,650 6 43,150 7 48,650 8 54,150 For families/households with more than 8 persons, add $5,500 for each additional person

90 FR 5917.

2025 HHS poverty guidelines AK / HI

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• Annual Update of the HHS Poverty Guidelines (90 FR 5917, 2025-01-17) (Department of Health and Human Services (Federal Register); record) checked 2026-10-12
  2025 Poverty Guidelines for Alaska Persons in family/household Poverty guideline 1 $19,550 2 26,430 3 33,310 4 40,190 5 47,070 6 53,950 7 60,830 8 67,710 For families/households with more than 8 persons, add $6,880; 2025 Poverty Guidelines for Hawaii Persons in family/household Poverty guideline 1 $17,990 2 24,320 3 30,650 4 36,980 5 43,310 6 49,640 7 55,970 8 62,300 For families/households with more than 8 persons, add $6,330

400% FPL cliff / enhanced PTC expired after 2025

Used by: The premium tax credit (Form 8962) and the net credit (Schedule 3 line 9). Status: verified.

• 26 U.S. Code § 36B (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Temporary rule for 2021 through 2025 In the case of a taxable year beginning after December 31, 2020, and before January 1, 2026, subparagraph (A) shall be applied without regard to "but does not exceed 400 percent"

No §36B amendment found in full text of Pub. L. 119-37, 119-75 (Consolidated Appropriations Act 2026), 119-86, 119-98, 119-103, 119-108; govinfo RSS titles through Pub. L. 119-111 show no health-subsidy law. congress.gov blocked (403); uscode.house.gov timed out.

Excess APTC repayment cap removed from 2026 (OBBBA §71305)

Used by: Excess advance premium tax credit repayment (Form 8962 line 29, Schedule 2 line 1a). Status: verified.

• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  Section 71305 of the OBBBA removes § 36B(f)(2)(B); effective for taxable years beginning after December 31, 2025

Federal engine 2.3 (B1): Form 8962 Part III repays the whole excess (line 28 left blank).

Where Form 8962 reaches the return: line 29 on Schedule 2 line 1a (in line 1z: Form 1040 line 17, Form 6251 line 10, Form 1116 line 20); line 26 on Schedule 3 line 9 (a payment); Form 2210 subtracts the premium tax credit

Used by: Excess advance premium tax credit repayment (Form 8962 line 29, Schedule 2 line 1a). Status: verified.

• Schedule 2 (Form 1040) (2025), Additional Taxes (Internal Revenue Service; record) checked 2026-10-12
  Excess advance premium tax credit repayment. Attach Form 8962
• Schedule 2 (Form 1040) (2026 early-release draft) (Internal Revenue Service; record) checked 2026-10-12
  Excess advance premium tax credit repayment. Attach Form 8962
• Schedule 3 (Form 1040) (2026 early-release draft) (Internal Revenue Service; record) checked 2026-10-12
  Net premium tax credit. Attach Form 8962
• Form 6251 (2025), Alternative Minimum Tax—Individuals (Internal Revenue Service; record) checked 2026-10-12
  Add Form 1040 or 1040-SR, line 16 (minus any tax from Form 4972), and Schedule 2 (Form 1040), line 1z
• Form 1116 (2025), Foreign Tax Credit (Internal Revenue Service; record) checked 2026-10-12
  Enter the total of Form 1040, 1040-SR, or 1040-NR, line 16, and Schedule 2 (Form 1040)
• Instructions for Form 2210 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Premium tax credit (Form 8962)
• 26 U.S. Code § 36B (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the tax imposed by this chapter for the taxable year shall be increased by the amount of such excess

Schedule E Parts II-III: lines 30-32 (partnerships and S corporations, passive and nonpassive columns), 33-37 (estates and trusts), line 41 to Schedule 1 line 5

Used by: Partnerships, S corporations, estates and trusts (Schedule E Parts II-III) and Form 8582's other passive activities. Status: verified.

• Schedule E (Form 1040) (2026 early-release draft) (Internal Revenue Service; record) checked 2026-10-12
  Total partnership and S corporation income or (loss). Combine lines 30 and 31; Add columns (g), (i), and (j) of line 29b; Add columns (h) and (k) of line 29a; Total estate and trust income or (loss). Combine lines 35 and 36; Total income or (loss). Combine lines 26, 32, 37, 39, and 40
• Instructions for Schedule E (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  complete Form 8582 to figure the amount of the loss to enter in; If you have passive activity income, complete Part II, column; Your share of the net income of an S corporation is not; trade or business, use Form 461 to figure your excess business
• Partner's Instructions for Schedule K-1 (Form 1065) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Report box 1 income (loss) from partnership trade or; Generally, the income (loss) reported in box 2 is a passive
• 26 U.S. Code § 704 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall be allowed only to the extent of the adjusted basis of such partner
• 26 U.S. Code § 465 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Limitation to amount at risk

Federal engine 2.3 (B2). Parts II-III are unchanged in the 2026 draft (Part I line 13 splits into 13a/13b). The K-1 amounts are entered after the basis (sections 704(d), 1366(d)) and at-risk (section 465) limits, as Schedule E line 28 takes them.

Form 8582 with other passive activities: line 2 (Part V), line 3, the special allowance only for rental real estate with active participation (line 4), Parts VI-VII (the allocation of the allowed and unallowed loss)

Used by: Partnerships, S corporations, estates and trusts (Schedule E Parts II-III) and Form 8582's other passive activities. Status: verified.

• Form 8582 (2026 early-release draft) (Internal Revenue Service; record) checked 2026-10-12
  All Other Passive Activities; Activities with net income (enter the amount from Part V, column (a)); Multiply line 7 by 50% (0.50). Do not enter more than $25,000
• Instructions for Form 8582 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Use Part V for all other passive activities.; Passive trade or business activities,; as actively participating in a partnership's rental real
• 26 U.S. Code § 469 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  no interest as a limited partner in a limited partnership shall be treated as an interest with respect to which the taxpayer actively participates; shall not exceed $25,000
• 26 CFR 1.469-5T, Material participation (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  The individual participates in the activity for more than 500 hours during such year
• 26 CFR 1.469-4, Definition of activity (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  The rental activity is insubstantial in relation to the trade or business activity

Material participation and grouping are the caller's assertion (which K-1 field an amount goes in). Each class is one activity: the Part VII ratio is exact for one activity per class and the caller's netting otherwise (disclosed).

A partner's net earnings from self-employment (K-1 box 14 code A) on Schedule SE; limited partners only guaranteed payments; an S corporation shareholder's share is not SE income

Used by: Partnerships, S corporations, estates and trusts (Schedule E Parts II-III) and Form 8582's other passive activities. Status: verified.

• Partner's Instructions for Schedule K-1 (Form 1065) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Code A. Net earnings (loss) from self-employment. If
• 26 U.S. Code § 1402 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  there shall be excluded the distributive share of any item of income or loss of a limited partner
• Instructions for Schedule SE (Form 1040) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Limited partners should include only guaranteed payments
• Shareholder's Instructions for Schedule K-1 (Form 1120-S) (2025) (Internal Revenue Service; record) checked 2026-10-12
  self-employment income and it isn

The excess business loss limitation (section 461(l)): 2026 threshold $256,000 ($512,000 joint); not modelled: the API refuses a return beyond it

Used by: Partnerships, S corporations, estates and trusts (Schedule E Parts II-III) and Form 8582's other passive activities. Status: verified.

• 26 U.S. Code § 461 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  Limitation on excess business losses of noncorporate taxpayers; $250,000 (200 percent of such amount in the case of a joint return)
• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  $256,000 ($512,000 for joint returns)

P.L. 119-21 section 70601 made the limitation permanent and reset its inflation base year to 2024 (indexing rule fed-ebl-threshold).

Net investment income from the K-1s: passive trade or business income is NII, nonpassive is not (Form 8960 line 4b) unless trading in financial instruments or commodities

Used by: Net investment income: the K-1 trade or business amounts (Form 8960 line 4b). Status: verified.

• 26 U.S. Code § 1411 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  a passive activity (within the meaning of section 469) with respect to the taxpayer; a trade or business of trading in financial instruments or commodities
• Form 8960 (2026 early-release draft) (Internal Revenue Service; record) checked 2026-10-12
  Adjustment for net income or loss derived in the ordinary course of a non-
• Instructions for Form 8960 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Nonpassive income not subject to NIIT is entered as a negative amount on line 4b.; Net income or loss from a section 162 trade or business; determining self-employment income subject to tax under

The estate or trust amount stays in line 4a (i8960: the Form 1041 K-1 box 14 code H adjustment goes on line 7, not an input). Section 1411(c)(6): items taken into account in self-employment income are excluded (i8960 line 4b).

§4973 6% tax on excess contributions (Form 5329 Parts III-VIII and X): the prior excess less the unused limit and the distributions, plus this year's excess, the 6% on the smaller of that and the December 31 value

Used by: Form 5329 Part III: excess traditional IRA contributions; Form 5329 Part IV: excess Roth IRA contributions; Form 5329 Part V: excess Coverdell ESA contributions; Form 5329 Part VI: excess Archer MSA contributions; Form 5329 Part VII: excess HSA contributions; Form 5329 Part VIII: excess ABLE contributions. Status: verified.

• 26 U.S. Code § 4973 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  shall not exceed 6 percent of the value of the account or annuity; the amount allowable as a deduction under section 219 shall be computed without regard to section 219(g); exceeds the contribution limit under section 529A(b)(2)(B)
• Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  Prior year excess contributions. Subtract line 13 from line 9; Enter 6% (0.06) of the smaller of line 16 or the value of your traditional IRAs on December 31; Include this amount on Schedule 2 (Form 1040), line 18; 2026 distributions from your HSAs from Form 8889, line 16
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  less your contributions to traditional IRAs and Roth IRAs for; reduced by the amount you contributed to traditional IRAs. But
• Form 5329 (2025) (Internal Revenue Service; record) checked 2026-10-12
  Include this amount on Schedule 2 (Form 1040), line 8

Not modelled (disclosed): the deemed contribution of a prior excess absorbed by this year's unused limit (i5329 line 10: the IRA Deduction Worksheet; line 43: Form 8889 line 13) — the engine has no traditional IRA or HSA deduction; the 6% itself is figured as the form does. Form 2210: i2210 line 2 takes Schedule 2 line 8 for the "additional tax on distributions only", so the 6% taxes are not in the required annual payment; Part XI's 100% is (a tax on a distribution; the 2026 draft's Schedule 2 line 5 with Part I).

The traditional IRA limit of Form 5329 line 10: $7,500 + $1,100 at 50, not above compensation; the spousal IRA (§219(c))

Used by: Form 5329 Part III: excess traditional IRA contributions. Status: verified.

• Notice 2025-67: 2026 retirement plan limitations (Internal Revenue Service; record) checked 2026-10-12
  increased from $7,000 to $7,500; from $1,000 to $1,100
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  $7,500 ($8,600 if age 50 or older at the end of 2026)
• 26 U.S. Code § 219 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  the compensation includible in the gross income of such individual’s spouse for the taxable year reduced by; the amount of any contribution on behalf of such spouse to a Roth IRA under section 408A for such taxable year
• Publication 590-A, Contributions to Individual Retirement Arrangements (IRAs) (2025) (Internal Revenue Service; record) checked 2026-10-12
  don’t subtract the loss from your salaries

Compensation (§219(f)(1), Pub 590-A What Is Compensation?): wages, and the net earnings from self-employment (Schedule C, K-1 box 14 code A) less the deductible part of SE tax and the plan deduction when positive. Not modelled: taxable alimony under a pre-2019 instrument, nontaxable combat pay, the difficulty-of-care payments of Pub 590-A. 2026 amounts only: the API refuses these inputs in a projected year.

A corrective withdrawal made in time is not a contribution (the *CorrectiveWithdrawal inputs): by the due date including extensions (a Coverdell ESA's before June 1 of the next year)

Used by: Form 5329 Part III: excess traditional IRA contributions; Form 5329 Part IV: excess Roth IRA contributions; Form 5329 Part V: excess Coverdell ESA contributions; Form 5329 Part VI: excess Archer MSA contributions; Form 5329 Part VII: excess HSA contributions; Form 5329 Part VIII: excess ABLE contributions. Status: verified.

• 26 U.S. Code § 4973 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  in a distribution to which section 223(f)(3) applies shall be treated as an amount not contributed
• 26 U.S. Code § 408 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  such distribution is accompanied by the amount of net income attributable to such contribution
• 26 U.S. Code § 530 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  before the first day of the sixth month of the taxable year following the taxable year
• 26 U.S. Code § 529A (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  rules similar to the rules of section 408(d)(4) (determined without regard to subparagraph (B) thereof) shall apply
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  You make the withdrawal before June 1, 2027; and; 6 months after the due date of your tax return, excluding
• 26 CFR 301.9100-2 (Cornell Legal Information Institute (Code of Federal Regulations); record) checked 2026-10-12
  An automatic extension of 6 months from the due date of a return excluding extensions is granted

The withdrawn earnings are income in the year the contribution was made (an IRA's: an early distribution excepted on Form 5329 line 2 with exception 21): the caller enters them in the income inputs; exception 21 itself is not an input (the corrective-distribution earnings are listed as not modelled with the other Form 5329 exceptions).

The Roth IRA limit of Form 5329 line 19 (Pub 590-A Worksheets 2-1 and 2-2): the traditional limit less the traditional contributions, reduced over the MAGI start

Used by: Form 5329 Part IV: excess Roth IRA contributions. Status: verified.

• Notice 2025-67: 2026 retirement plan limitations (Internal Revenue Service; record) checked 2026-10-12
  between $153,000 and $168,000; is between $242,000 and $252,000 for
• 26 U.S. Code § 408A (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  $15,000 ($10,000 in the case of a joint return or a married individual filing a separate return); shall apply to any reduction under this subparagraph; any amount included in gross income under subsection (d)(3) shall not be taken into account
• Publication 590-A, Contributions to Individual Retirement Arrangements (IRAs) (2025) (Internal Revenue Service; record) checked 2026-10-12
  Round the result up to the nearest $10; rounded to at least three places; you can refigure your AGI solely for the purpose of figuring your
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  $153,000 if single, head of household, or married filing
• 26 U.S. Code § 219 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  No dollar limitation shall be reduced below $200

Line 5 is the exact ratio (the worksheet asks for at least three places). The Worksheet 2-1 add-backs of lines 4-9 (the IRA and student-loan deductions, foreign earned income, savings-bond interest, employer adoption benefits) are 0: the engine models none of them. The Note's refigured AGI recomputes the taxable social security (Pub 915) and Form 8582's special allowance without the conversion, only when line 10 is over the end of the range, as the worksheet says.

Form 5329 line 27's Coverdell ESA limit ($2,000, or less under the contributors' MAGI limits) and line 50's ABLE limit ($20,000 for 2026, plus an employed beneficiary's ABLE-to-work amount): the API's defaults

Used by: Form 5329 Part V: excess Coverdell ESA contributions; Form 5329 Part VI: excess Archer MSA contributions; Form 5329 Part VIII: excess ABLE contributions. Status: verified.

• 26 U.S. Code § 4973 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  exceeds $2,000 (or, if less, the sum of the maximum amounts permitted
• Rev. Proc. 2025-32: 2026 inflation-adjusted items (incl. One Big Beautiful Bill amendments) (Internal Revenue Service; record) checked 2026-10-12
  beginning in 2026, $20,000
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  smaller of $2,000 or the sum of the maximum amounts the; may not exceed $20,000 plus

The contributors' Coverdell MAGI phase-out (§530(c)) and the Archer MSA limit (Form 8853 lines 3-4, 65% / 75% of the HDHP deductible) are the caller's (coverdellLimit, archerMsaLimit).

The HSA limit of Form 5329 line 43 (Form 8889 line 8): $4,400 self-only, $8,750 family, + $1,000 at 55; spouses with family coverage split the family limit equally; Archer MSA contributions reduce it

Used by: Form 5329 Part VII: excess HSA contributions. Status: verified.

• Rev. Proc. 2025-19: 2026 HSA and HDHP amounts (Internal Revenue Service; record) checked 2026-10-12
  deductible health plan is $4,400; deductible health plan is $8,750
• 26 U.S. Code § 223 (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  has attained age 55 before the close of the taxable year
• Publication 969, Health Savings Accounts and Other Tax-Favored Health Plans (2025) (Internal Revenue Service; record) checked 2026-10-12
  Rules for married people. If either spouse has family; amount contributed to both spouses’ Archer MSAs. After; additional contribution to their own HSA.

The coverage is the caller's assertion for the whole year as an eligible individual (an HDHP, no other coverage, not enrolled in Medicare); a part-year or last-month-rule limit, or an agreed split between spouses, goes in hsaLimit (Form 8889 line 8). The equal split is applied on a joint return when both spouses have coverage and either has family coverage.

Form 5329 Parts X and XI (Trump accounts, the account beneficiary before the year they turn 18): 6% of the excess over $5,000 less the §530A(d)(5) distributions; 100% of the distributed excess's earnings

Used by: Form 5329 Part X: excess Trump account contributions; Form 5329 Part XI: 100% of a distributed Trump account excess's earnings. Status: verified.

• 26 U.S. Code § 530A (Cornell Legal Information Institute (text of the U.S. Code, Title 26); record) checked 2026-10-12
  100 percent of the amount of net income attributable to such excess; in which the account beneficiary attains age 18, the term
• Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  Additional Tax on Excess Contributions to Trump Accounts During the Growth Period; Enter 100% of line 62; Include this amount on Schedule 2 (Form 1040), line 5
• Instructions for Form 5329 (2026 draft) (Internal Revenue Service; record) checked 2026-10-12
  The 2026 contribution limit is $5,000.

Line 56 (the 2025 excess) is 0 for 2026: contributions began July 4, 2026. The excess itself (line 57, exempt contributions excluded) is the caller's.