Delaware state income tax: engine rules, 2026

How the tax is computed

Every step the engine takes for Delaware, in the order it takes them. Steps marked with a filing status or household type apply only there. Each step links the section below that carries Delaware's figures and the official sources for it; the calculation order page describes every step for all jurisdictions.

What each filing status gets, read back from the engine for a household with $1 of income (so below every phase-out and income test):

1. Combined separate return (two columns on one form) joint returns with each spouse's own amounts given A joint return that gives the spouse's own amounts is also computed as two separate returns on one form: each spouse's own income (the items with no owner, such as interest, gains and Social Security, half each) at that spouse's age and facts, the per-dependent credits divided between the columns the cheapest way. The lower of that and the joint return is the tax; the joint return's lines stay in the breakdown.
   Delaware's values · engine step (combined_separate_tax). Sources (Deductions, exemptions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1105-1118) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28)
2. Per-person mode joint returns with the spouse's age given On a joint return with the spouse's age given, every age test the state applies per taxpayer is evaluated for each spouse at their own age. Without it one household age applies to both.
   engine step (compute_state_tax_detail). Engine convention, no external source: The engine cannot know the second spouse's age unless told.
3. Blindness and disability, per person only when the caller says a person is blind or disabled The filer is person one; the spouse counts only on a joint return and only when the caller says so (there is no household convention as for age). Where a state lets a disabled person (and, where it says so, a blind one, or one whose spouse is disabled) qualify for its general retirement exclusion before the age, that person is treated as having reached the age for that exclusion only. Of the 42 taxing jurisdictions, these have a blind amount: Arizona, Arkansas, California, Colorado, Delaware, the District of Columbia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, North Dakota, Oklahoma, Oregon, Utah, Vermont and Virginia; these have none: Alabama, Connecticut, Georgia, Louisiana, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, West Virginia and Wisconsin. A disability route is calculated in Arkansas, the District of Columbia, Georgia, Hawaii, Idaho, Iowa, Maryland, Michigan, New Jersey, Oregon and West Virginia.
   engine step (compute_state_tax_detail). Engine convention, no external source: Who is blind or disabled is the caller's statement; the engine has no household convention for it.
4. Rate schedule and standard deduction by filing status Single uses the single schedule and deduction; married filing jointly the joint ones. Head of household and married filing separately follow the two steps below.
   Delaware's values · engine step (select_brackets). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
5. Married filing separately Where the state publishes its own separate schedule, that one (with half the joint deduction unless a separate deduction is set). Where one schedule applies to every status, that schedule unscaled with the single deduction. Otherwise the joint schedule with every threshold and the deduction halved (computed as the joint tax on twice the income, halved).
   Delaware's values · engine step (select_brackets). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
6. Head of household The state's head-of-household schedule where it has one, else the single schedule; the head-of-household deduction where set, else the single deduction.
   Delaware's values · engine step (select_brackets). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
7. The income total every income test uses Other ordinary income + retirement distributions (before any exclusion) + conversion + federally taxable Social Security + long-term gains + Railroad Retirement Tier 2. It stands in for federal adjusted gross income in every threshold, cliff and phase-out below; state subtractions do not reduce it.
   engine step (compute_state_tax_detail). Engine convention, no external source: The inputs are the federal AGI components, so their sum is federal AGI for these income types.
8. Attributing income to each spouse joint returns with each spouse's own amounts given With a caller's split (the API's spouse object), each spouse's own distributions (employer-plan money included), pension, public pension, conversion, wages and military pay; spouse 2's shares are clamped into the household totals and spouse 1 gets the rest. Without a split, in per-person mode, every item is divided 50/50. Social Security is divided by each spouse's own gross benefits where the caller gives spouse.socialSecurityGross, else 50/50; other ordinary income and gains are always divided 50/50 where a rule needs a per-person amount. The split is used only where a state's rule is per taxpayer; household totals stay authoritative for the base and the income tests.
   engine step (compute_state_tax_detail). Engine convention, no external source: Equal attribution is the neutral split when the owner of a dollar is not known.
9. Keeping the per-spouse shares inside the household joint returns with each spouse's own amounts given After the public-pension and employer-pension carve-outs, if the two spouses' remaining shares add up to more than the household's exclusion-eligible distributions (an inconsistent split), spouse 1's share is reduced so they do not.
   engine step (compute_state_tax_detail). Engine convention, no external source: Input normalisation.
10. Military retirement pay The state's military rule runs first, on military pay alone, per taxpayer: each spouse's own pay at their own age when attributed, otherwise half each at the household age on a joint return. Exempt dollars leave the base; the rest become pension dollars for the general retirement rules. Where the state lets a disabled retiree qualify at any age, a disabled person is treated as having reached the rule's age.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Military retirement pay): Sc02 (checked 2026-10-12)
11. One taxpayer's military exemption Exempt: all of it (below the age split, up to the younger cap). Capped: up to the cap for the age tier, plus the earned-income bonus below the age split when the taxpayer's own wages exceed the threshold, less the taxpayer's own Social Security where the rule says so. Percentage: the percentage (below the age split, up to the younger cap). Then the income limit: above it the exemption is lost, or phased out over the range where one is set.
    Delaware's values · engine step (military_exempt_one). Sources (Military retirement pay): Sc02 (checked 2026-10-12)
12. Capital-loss deduction off the base The deduction comes off the other ordinary income (negative income, as Form 1040 line 7a is), so the base and every state-AGI figure summed from it carry it; WI no more than Wisconsin ordinary income (Schedule WD line 28(c)). States whose base is federal taxable income (with the caller's figure) already have it there and take it only once. Engine 1.13.1: the allowed rental loss comes off the same way, on its own line (rental_loss_deduction).
    Delaware's values · engine step (compute_state_tax_detail). Sources (Capital gains): Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Code Title 30, Chapter 11, Subchapter II (§1105, resident taxable income) (checked 2026-10-12); 2025 PIT-RES Instructions (checked 2026-10-12); 2025 Schedule D (Form 1040), Capital Gains and Losses (checked 2026-10-12)
13. Social Security exempt None of the federally taxable benefit enters the base.
    Delaware's values · engine step (ss_amount_in_state_base). Sources (Social Security): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(4)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
14. Retirement exclusion per spouse (both ages known) joint returns with the spouse's age given Full-exclusion states exclude each qualifying spouse's own dollars. Capped states give each spouse the single cap for their own age against their own eligible dollars (pension dollars only where the exclusion is pension-only; employer dollars only below the IRA age), less their military exclusion and their own Social Security offset (by the spouse's stated gross benefits, else half). Per-return states (and the pooled-if-both-qualify rule when both qualify) apply the joint cap to the couple's pooled eligible dollars when either spouse qualifies. The income tests then apply once to the summed deduction.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
15. Retirement exclusion (household) The distributions eligible for the exclusion go through the exclusion below. Taxable public-pension dollars left by a cap are not eligible; below the IRA age only employer-plan dollars are.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
16. Retirement exclusion per spouse (declared split) joint returns with each spouse's own amounts given With a spouse split in a per-taxpayer state, each spouse's own eligible dollars draw that spouse's single cap (less their military exclusion); an income limit then applies once to the sum.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
17. Conversion taxed or exempt In full-exclusion states a conversion is exempt at the qualifying age (at any age where the state says so). Elsewhere, unless pooled above, it is ordinary income taxed in full.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Roth conversions): Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
18. Cap by age tier The full cap at or above the exclusion age, the lower cap at or above the partial age, otherwise none. Joint returns use the joint cap; every other status the single cap.
    Delaware's values · engine step (retirement_distributions_in_state_base). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
19. The capped deduction Deduction = the smaller of the eligible distributions and the cap, then reduced by the income limit above; the rest of the distributions stays in the base.
    Delaware's values · engine step (retirement_distributions_in_state_base). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
20. One taxpayer's cap joint returns with the spouse's age given For per-spouse calculations, each spouse's cap is the single-column cap for their age tier.
    Delaware's values · engine step (per_taxpayer_cap_single). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
21. Long-term gains in the base Where gains are taxed as ordinary income: net long-term gain less the flat exclusion (never below zero), times the inclusion share. Elsewhere none enters.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Capital gains): Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Code Title 30, Chapter 11, Subchapter II (§1105, resident taxable income) (checked 2026-10-12); 2025 PIT-RES Instructions (checked 2026-10-12); 2025 Schedule D (Form 1040), Capital Gains and Losses (checked 2026-10-12)
22. Interest and dividends in the retirement pool Where the state's retirement exclusion covers investment income, the other ordinary income that is not wages (interest, dividends and other income; the API's ordinaryIncome) joins the pool, split half and half between spouses in per-person mode. Internal callers whose ordinary income is untyped keep it out.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
23. Retirement and investment pool per spouse joint returns with the spouse's age given Each spouse's pool = own distributions + own conversion + half the long-term gain in the base (+ half the interest and dividends where the state pools them, pool-ordinary) + (where the state counts earned income) up to the earned-income amount of their own wages, against the cap for their own age. The pool above the caps is taxed.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
24. Retirement and investment pool Distributions + conversion + long-term gain in the base (+ wages up to the earned-income amount per qualifying person) form one pool against the cap for the household age (each spouse's own pool and cap with a split in a per-taxpayer state). The pool above the cap is taxed as ordinary income; conversions and gains are not added separately.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
25. Capital loss inside the retirement pool (GA, DE) Where gains join the retirement pool (GA, DE), the pool holds gains net of losses: the exclusion is at most the pool less the deducted loss (half each spouse in per-person mode); the loss itself leaves the base at capital-loss-deduction.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Capital gains): Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Code Title 30, Chapter 11, Subchapter II (§1105, resident taxable income) (checked 2026-10-12); 2025 PIT-RES Instructions (checked 2026-10-12); 2025 Schedule D (Form 1040), Capital Gains and Losses (checked 2026-10-12)
26. Exemption for blindness only when the caller says a person is blind or disabled An extra exemption for each blind person (the filer, and the spouse on a joint return). Where the state's exemption is for a person who is blind or disabled, a disabled person below the state's age limit (if any) qualifies too, one exemption per person either way.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Blindness and disability): 30 Del. C. 1108 (checked 2026-10-12); 2025 PIT-RES instructions (archived copy) (checked 2026-09-28)
27. Age subtraction At or above the age: the single amount, or the joint amount on a joint return (both spouses at the household age). In per-person mode, half the joint amount (or the single amount) per qualifying spouse. Plus the low-income amount below the income test; less the military exclusion where the statute says so; limited to the spouse's own income where the statute says so. Where the statute counts income from any source, the taxable remainder of the spouse's own public pension is part of that own income. Where the state says so, the Social Security that offsets a person's amount is that person's own.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Age 65+ subtractions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1108(b), 1110(b)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
28. Pension exclusion below the age, and the low-income exclusion A person at or under the age excludes employer and government pension income up to the amount (one exclusion per person, so military pay already excluded counts toward it; IRA money and disability pay do not qualify). A person at the age or disabled, with earned income under the limit and income at most the limit, excludes the amount; on a joint return both must qualify, with doubled limits and amount.
    Delaware's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(3)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28); 2025 PIT-RES instructions (filing status 4 and line 6) (checked 2026-09-28)
29. State taxable income Other ordinary income + Social Security, retirement income, conversion and gains left in the base − standard deduction − personal exemption − age subtractions.
    engine step (compute_state_tax_detail). Engine convention, no external source: The order of subtraction follows the state forms; each amount is sourced at its own step.
30. No tax at or below zero State taxable income at or below zero returns a tax of 0 (credits are not refundable), unless the state has a tax computed apart from taxable income that still applies (next step).
    engine step (compute_state_tax_detail). Engine convention, no external source: Every credit the engine carries is nonrefundable, so nothing below can make a zero tax negative; each credit is sourced at its own step.
31. Separate-return scaling married filing separately For the halved-joint rule, taxable income is doubled before the schedule and the result halved.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
32. The rate schedule Each bracket's rate on the part of taxable income inside it, summed. No rounding: the result is carried in full precision.
    Delaware's values · engine step (apply_state_brackets). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
33. Per-exemption credit The credit per exemption: two on a joint return, one otherwise, or the state's own count for a head of household. Where the state sets an income limit there is no credit above it (the joint limit for joint returns and heads of household).
    Delaware's values · engine step (compute_state_tax_detail). Sources (Deductions, exemptions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1105-1118) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28)
34. Credit per dependent only when the caller lists dependents A credit per dependent, under the same income cutoff and phase-out as the personal credits where the state has them (each dependent credit loses the same amount per step, floored as a group).
    Delaware's values · engine step (compute_state_tax_detail). Sources (Deductions, exemptions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1105-1118) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28)
35. Senior credit The credit per taxpayer at or above the age: two on a joint return at the household age, one per qualifying spouse in per-person mode. A head of household's extra personal credit is not a second senior credit.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Age 65+ subtractions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1108(b), 1110(b)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
36. Credits cannot make the tax negative The credits are subtracted and the result floored at zero.
    engine step (compute_state_tax_detail). Engine convention, no external source: Every credit the engine carries is nonrefundable; each credit is sourced at its own step.
37. Qualifying surviving spouse qualifying surviving spouse returns A qualifying surviving spouse (filingStatus qss) is one person on the return, taxed from the single figures with the state's own treatment of the status laid over them: where the state says so, the joint rate schedule, the joint standard deduction, the joint personal exemption, the joint income limits and phase-outs (only those the state sets for joint returns), the married 65+ and blindness amounts, or the head-of-household return; where the state gives the status nothing of its own, the single return. The federal figures the engine derives for the status are the federal qualifying-surviving-spouse ones (the joint standard deduction, the married 65+ amount).
    Delaware's values · engine step (state_tax_effective_config). Sources (Rate schedule): Delaware Code Title 30, Chapter 11, Subchapter I (30 Del. C. § 1102) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
38. Railroad Retirement benefits only when the caller gives Railroad Retirement benefits Railroad Retirement benefits are never taxed by a state (45 U.S.C. §231m). Tier 2 (railroadRetirementTier2) is in the income total the tests use but never in the base. Tier 1 (railroadRetirementTier1) is a part of the gross benefits (socialSecurityGross); its share of the taxable benefits is taken out of the Social Security every state rule sees, so a state that taxes Social Security never reaches it. Where a state's worksheet says so, the benefits reduce a retirement cap or subtraction (ID, IN, MD, ME, MN: both tiers; MI: the taxable railroad benefits); Minnesota's and Utah's Social Security rules test an income without them, Minnesota's, New Jersey's and California's retirement income tests an income without Tier 2; Ohio and Delaware test their own AGI everywhere, which never holds the benefits.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Social Security): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(4)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
39. The capital-loss deduction the state allows With a net capital loss (capitalLoss): the smaller of the loss and the state's limit (the federal $3,000 / $1,500 where the state follows the federal return; MA $2,000, and no more than the interest and dividends); AL the loss less the part carried in, unlimited; PA and NJ none. It comes off the income total the income tests use (and the Social Security worksheets' income); the gross-income filing test (LA) reads the total before it. Engine 1.13.1: with a rental loss (rentalNetIncome below 0, the federal Schedule E line 26 amount) the state allows, the whole loss where the state starts from federal AGI or follows the federal schedule, none in PA and NJ (rental_loss_no_offset): it comes off the same income the same way; a rental profit is other ordinary income.
    Delaware's values · engine step (compute_state_tax_detail). Sources (Capital gains): Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Code Title 30, Chapter 11, Subchapter II (§1105, resident taxable income) (checked 2026-10-12); 2025 PIT-RES Instructions (checked 2026-10-12); 2025 Schedule D (Form 1040), Capital Gains and Losses (checked 2026-10-12)
40. Each spouse's own Social Security joint returns On a joint return, each spouse's own Social Security is the spouse's share of the benefits by spouse.socialSecurityGross when the caller gives it (Tier 1 railroad benefits left out), else half each. It is what the per-spouse rules read: Colorado's per-spouse subtraction, Rhode Island's per-spouse modification, and the Maine, Maryland and other retirement caps reduced by the benefits each spouse received (with each spouse's own railroad benefits where the state counts them).
    Delaware's values · engine step (compute_state_tax_detail). Sources (Social Security): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. § 1106(b)(4)) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12)
41. Nonrefundable earned income credits SC, UT, DE and VA: a share of the federal EIC, nonrefundable, with the other credits (SC at most $200; DE, or its refundable share, the larger; VA, the larger of it and the credit for low-income individuals ($300 per exemption at a family income within the poverty guideline), or the refundable share, the larger).
    Delaware's values · engine step (st_compute). Sources (Deductions, exemptions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1105-1118) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28)
42. Refundable state credits The credits paid beyond the tax (reported in refundableCredits; netTax = totalTax less them): earned income credits as a share of the federal EIC with each state's own age band (OK on the 2020 federal credit, DC's own childless schedule, the CalEITC table, MN's Working Family Credit), the NYC EIC and school tax credits, and the property-tax, renter, grocery and senior credits of MA, MI, NJ, ID, HI, NM, OK, AZ, NY, RI, WV, ME, DC, MN, MO, WI, IN and MT, each on its own income measure. Engine 1.13.1: a part-year NYC resident's school tax credits (the Table 2 proration chart and the rate-reduction amount on IT-360.1 line 47; IT-203 lines 60 / 60a for a part-year state resident).
    Delaware's values · engine step (state_tax_refundable_credits). Sources (Deductions, exemptions and credits): Delaware Code Title 30, Chapter 11, Subchapter II (30 Del. C. §§ 1105-1118) (checked 2026-10-12); Delaware Individual Income Tax Return Resident Instructions 2025 (PIT-RES) (checked 2026-10-12); Delaware Division of Revenue: PIT-RES_Instructions_2025-01.pdf (checked 2026-09-28)

Worked examples

Computed by the engine for the fixed households below (the same ones for every state, so states compare directly). Federal tax is not supplied, so a federal-tax deduction is not taken; the income tests use the sum of the components as income.

Line by line

The intermediate lines the engine records while it computes each example (its detail record, printed as it comes out; lines that are zero are left out). The engine's documentation build checks that the lines add up to the taxable income and the tax, for every state, filing status and a grid of households. Each line links the engine step that produces it.

After 2026: how the amounts move

A request with projection (API) estimates a later tax year from these rules: every dollar amount and age test below moves the way Delaware's law moves it. Rates and the rules themselves stay the 2026 ones (how projection works).

Enacted for later years, not applied by the projection

• 60+ military pension exclusion becomes the greater of the $12,500 pension exclusion or $15,000 (2027) / $20,000 (2028) / $25,000 (2029+) of U.S. military pension. (2027-2029+)
  • 30 Del. C. § 1106(b)(3) (Title 30, Chapter 11, Subchapter II) (Delaware Code Online (Delaware Legislative Council), statute): 60+ military route. Quoted: "2. for persons age 60 or older, the greater of: a. amounts received, not to exceed $12,500". Checked 2026-10-12.

What the engine does not calculate, and known approximations

• ordinaryIncome is read as interest, dividends and other investment income: at 60 or over it counts toward the $12,500 exclusion with pensions, IRA distributions and gains (engine 1.8.0), split half and half between spouses. Ordinary income that is not eligible retirement income (business income, for example) belongs in wages, where it is not pooled.
• With a spouse split, jointly held long-term gains are attributed half to each spouse.
• Filing status 4 (combined separate) is computed only with the spouse object, and the lower of it and the joint return (filing status 2) is the tax. Each spouse's own wages and retirement income are theirs; the items without an owner (ordinaryIncome, gains, Social Security) are split half and half, as the instructions do for jointly titled property, and the $110 dependent credits go to the column that can use them. Without the spouse object a joint request is a joint return.

What the engine does not calculate for any state (itemized deductions, credits beyond those listed, part-year residents, and more) is listed on the calculation order page.

Verification

Worksheet-tested Golden and unit tests follow the PIT-RES instructions, Line 6 pension exclusion worksheet (including the per-taxpayer columns).

• Golden scenarios (hand-computed expected tax, asserted to within $1): DECONV1, DELTCG1, DESP1, DESP2, DESP3.
• State-specific unit tests: test_de_age_gate, test_de_senior_stdded_and_credits, test_mfs_one_schedule_states, test_de_pool_conversion_and_ltcg, test_de_per_spouse_pool_ltcg, test_localities_endpoint, test_de_spouse_split_pool, test_spouse_share_clamps_c, test_s2_de_combined_separate, test_s2_in_de_person_rules, test_400s, test_equal_ages_split_matches_legacy_split, test_military_tiers, test_de_senior_credit_at_60, test_de, test_worked_ratios, test_engine_paths.
• Structural tests covering every state: 7.
• State forms and worksheets followed in the test derivations: PIT-RES instructions, Line 6 pension exclusion.