State tax docs / States / Massachusetts

Massachusetts state income tax: engine rules, 2026

How the QuantCalc engine computes Massachusetts tax for tax year 2026, rule by rule, with the official source for each rule. Verification status: Worksheet-tested (what this means).

On this page: How the tax is computed · Rate schedule · Deductions, exemptions and credits · Age 65+ subtractions and credits · Social Security · IRA, 401(k) and private pensions · Public pensions · Military retirement pay · Wages · Roth conversions · Capital gains · Surtaxes and recapture · Blindness and disability · Part-year and nonresident returns · Worked examples · After 2026 · Not calculated · Verification. Machine-readable: this state's entry in the engine config and the provenance file (key MA).

How the tax is computed

Every step the engine takes for Massachusetts, 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 Massachusetts'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):

	Single	Married filing jointly	Married filing separately	Head of household
Rate schedule used	single schedule	joint schedule	joint schedule, thresholds halved	single schedule
Top rate	5% flat	5% flat	5% flat	5% flat
Standard deduction, under 65	$4,400	$8,800	$1	$6,800
Standard deduction at 70 (joint: both 70)	$4,400	$8,800	$1	$6,800
Personal exemption	none	none	none	none
Age subtractions at 70 (joint: both 70)	$700	$1,400	none	$700

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.
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.
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.
Massachusetts's values · engine step (select_brackets). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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).
Massachusetts's values · engine step (select_brackets). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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.
Massachusetts's values · engine step (select_brackets). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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.
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.
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.
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Military retirement pay): Tax treatment of government pensions (checked 2026-10-12)
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.
Massachusetts's values · engine step (military_exempt_one). Sources (Military retirement pay): Tax treatment of government pensions (checked 2026-10-12)
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).
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Capital gains): Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12)
Public pension exemption Public-pension dollars leave the base, uncapped or up to the per-taxpayer cap (each spouse's own public pension against their own cap when attributed), without using up the general exclusion the remaining distributions may claim. Capped-out public dollars stay taxable and cannot draw the private exclusion.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Public pensions): Tax treatment of government pensions (Massachusetts DOR) (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12)
Social Security exempt None of the federally taxable benefit enters the base.
Massachusetts's values · engine step (ss_amount_in_state_base). Sources (Social Security): Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (IRA, 401(k) and private pensions): Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Roth conversions): Tax treatment of non-government pensions and retirement plans (Massachusetts DOR) (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Capital gains): Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Blindness and disability): Personal income tax exemptions (checked 2026-10-12)
Dependent exemptions and deductions only when the caller lists dependents An amount per dependent subtracted like the personal exemption: the state's flat amount, or the stepped per-exemption amount the filer gets, or the state's own income steps; nothing above an income limit where there is one; a percentage phase-out per income step where there is one; one more for a dependent in an age band or a student up to an age, for a dependent born in the year, and for a disabled dependent; a deduction per dependent beyond the first on joint and head-of-household returns; and a child deduction by an income table for dependents under an age. A head of household's status exemption that already holds one dependent's amount counts one fewer. Where the state says so, the phase-out is measured on the state AGI (the base before deductions).
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Deductions, exemptions and credits): Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Age 65+ subtractions and credits): Personal income tax exemptions (checked 2026-10-12)
Deduction for Social Security and Medicare paid on wages Per person, the rate times that person's own wages, at most the per-person maximum; not combined or moved between spouses. On a joint return the spouse's wages come from the spouse amounts; without them the wages are the filer's.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Wages): 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); Topic no. 751, Social Security and Medicare withholding rates (IRS) (checked 2026-10-12)
Exemptions against the base-rate income first The exemptions offset the income taxed at the base rate (wages, pensions, IRA dollars and conversions after the wage deduction) first. On a separate return what they cannot offset is lost; the other statuses carry it to the short-term gains, then interest and dividends, then long-term gains (see the short-term gains step).
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Capital gains): Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12)
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.
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.
Short-term gains at their own rate The short-term gains in the base are taxed at their own rate instead of on the schedule. Deductions and exemptions come off the schedule income first; any left over reduce the short-term gains. Where the state orders them (engine 1.8.0): the exemptions left after the base-rate income reduce the short-term gains, then interest and dividends (taxed on the schedule), then long-term gains.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Capital gains): Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12)
Separate-return scaling married filing separately For the halved-joint rule, taxable income is doubled before the schedule and the result halved.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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.
Massachusetts's values · engine step (apply_state_brackets). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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.
No tax at low income, and the limited-income cap With the state AGI (the income in the base before deductions and exemptions) at most the filing status's limit, the tax is at most the rate times the AGI above the no-tax amount, so none at or below it. Not on a separate return.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Deductions, exemptions and credits): Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01)
Surtax on high income The rate times state taxable income over the filing status's threshold.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Surtaxes and recapture): Massachusetts 4% Surtax on Taxable Income (checked 2026-10-12)
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).
Massachusetts's values · engine step (state_tax_effective_config). Sources (Rate schedule): Tax rates (Massachusetts DOR) (checked 2026-10-12); Tax treatment of government pensions (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Social Security): Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12)
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.
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Capital gains): Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12)
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).
Massachusetts's values · engine step (compute_state_tax_detail). Sources (Social Security): Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12)
Rent and homeowner property tax deductions (MA, IN) MA: half the rent paid on the principal residence, at most $4,000; IN: the rent, at most $3,000, and the property tax paid on the principal residence, at most $2,500; each per return and smaller on a separate return, off income.
Massachusetts's values · engine step (st_compute). Sources (Deductions, exemptions and credits): Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01)
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).
Massachusetts's values · engine step (state_tax_refundable_credits). Sources (Deductions, exemptions and credits): Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01)

Rate schedule

A flat 5% on state taxable income.

Tax rates (Massachusetts DOR), Massachusetts Department of Revenue. Massachusetts taxes wages, interest, dividends, other income and most long-term capital gains at a flat 5.00%, with a 4% surtax on income over $1,107,750 in tax year 2026; short-term gains are 8.5% and collectibles 12%. Checked 2026-10-12.
Tax treatment of government pensions, Massachusetts Department of Revenue. Massachusetts Department of Revenue: "Distributions made to you from a Massachusetts state and local employee contributory plan are excluded from Massachusetts gross income even though they are included in federal gross income." (and 1 more quoted passage) Checked 2026-10-12.

Deductions, exemptions and credits

Standard deduction (or the exemption the engine carries in its place): $4,400 single, $8,800 married filing jointly, $6,800 head of household.

Personal income tax exemptions (Massachusetts DOR), Massachusetts Department of Revenue. Massachusetts allows a personal exemption of $4,400 (single/MFS), $6,800 (head of household) or $8,800 (married filing jointly), plus $700 per taxpayer age 65 or older. Engine 1.7.0: Form 1 line 2b: $1,000 per dependent; heads of household and joint filers add $1,000 per dependent to the No Tax Status amount and $1,750 per dependent to the Limited Income Credit limit. Checked 2026-10-12.
2025 Massachusetts Form 1 Instructions, Massachusetts Department of Revenue. No Tax Status at Massachusetts AGI of $8,000 single, $14,400 head of household, $16,400 joint (plus $1,000 per dependent); the Limited Income Credit up to $14,000 / $25,200 / $28,700 caps the tax at 10% of the AGI over the No Tax Status amount. Not for married filing separately. Engine 1.7.0: Form 1 line 2b: $1,000 per dependent; heads of household and joint filers add $1,000 per dependent to the No Tax Status amount and $1,750 per dependent to the Limited Income Credit limit. Checked 2026-10-12.
2025 Massachusetts Form 1 Instructions, Massachusetts Department of Revenue. Earned income credit (engine 1.12.0, refundableCredits): 40% of the federal EIC. Senior Circuit Breaker credit (engine 1.12.0): 65 or older, real estate tax or 25% of rent over 10% of qualifying income, at most $2,820, within the income and assessed value limits. Checked 2026-10-01.
2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access), Massachusetts Department of Revenue. Senior Circuit Breaker credit (engine 1.12.0): 65 or older, real estate tax or 25% of rent over 10% of qualifying income, at most $2,820, within the income and assessed value limits. Checked 2026-10-01.
Massachusetts 2025 Form 1 Instructions, Massachusetts Department of Revenue. Rental deduction (engine 1.12.0): half the rent paid on the principal residence, at most $4,000 per return ($2,000 married filing separately). Checked 2026-10-12.
Massachusetts 2025 Form 1 Resident Income Tax Return, Massachusetts Department of Revenue. Rental deduction (engine 1.12.0): half the rent paid on the principal residence, at most $4,000 per return ($2,000 married filing separately). Checked 2026-10-12.
General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov), Massachusetts Department of Revenue. Rental deduction (engine 1.12.0): half the rent paid on the principal residence, at most $4,000 per return ($2,000 married filing separately). Checked 2026-10-01.

Age 65+ subtractions and credits

At age 65 or older: $700 is subtracted from the base ($1,400 for a married couple filing jointly when both qualify), against any income. With the spouse's age given, each spouse qualifies on their own age.

Personal income tax exemptions, Massachusetts Department of Revenue. Massachusetts Department of Revenue: "Single $4,400 Married filing separate $4,400 Head of household $6,800 Married filing joint $8,800" (and 1 more quoted passage) Checked 2026-10-12.

Social Security

Social Security benefits are fully exempt: none of the federally taxable amount enters the state base.

API value: socialSecurityRule: "exempt". The engine's input is the federally taxable amount; income tests use the sum of the income components as the adjusted-gross-income proxy.

Massachusetts tax information for seniors and retirees, Massachusetts Department of Revenue. Social Security benefits are excluded from Massachusetts gross income. Checked 2026-10-12.
Differences Between MA and Federal Tax Law for Personal Income, Massachusetts Department of Revenue. Social Security benefits are not included in Massachusetts income even when federally taxable. Checked 2026-10-12.

IRA, 401(k) and private pensions

No exclusion: pension, annuity and IRA/401(k) distributions are taxed as ordinary income.

Source review notes (what the sources do not state outright, or what the engine does not carry):

Engine taxes traditional IRA distributions in full; Massachusetts excludes the recovery of previously taxed (non-deductible for MA) contributions. The iraBasis input (the federal after-tax basis) is not read for Massachusetts: the Massachusetts basis is every contribution Massachusetts taxed, recovered before any distribution is taxed.

Massachusetts tax information for seniors and retirees, Massachusetts Department of Revenue. Private pension, annuity, 401(k) and traditional IRA distributions are taxable in Massachusetts at the 5% rate, with no age-based exclusion. Checked 2026-10-12.
Differences Between MA and Federal Tax Law for Personal Income, Massachusetts Department of Revenue. Traditional IRA contributions are not deductible for Massachusetts, so IRA distributions are taxable only above previously taxed (MA-basis) contributions. Checked 2026-10-12.

Public pensions

Public (government) pension dollars, entered as pensionPublic, are exempt with no dollar cap. They do not use up the capped exclusion that other retirement income may claim.

Tax treatment of government pensions (Massachusetts DOR), Massachusetts Department of Revenue. Distributions from Massachusetts state/local and federal contributory pensions are excluded from Massachusetts gross income. Checked 2026-10-12.
Differences Between MA and Federal Tax Law for Personal Income, Massachusetts Department of Revenue. Pensions paid by the Commonwealth and its cities and towns and contributory plans of other states and the federal government are excluded from Massachusetts income. Checked 2026-10-12.

Military retirement pay

Military retirement pay is fully exempt, at any age.
Rules are applied per taxpayer at that person's own age when the spouse's age is given. API value: rules.militaryRetirement.treatment: "exempt".

Tax treatment of government pensions, Massachusetts Department of Revenue. US military pensions are excluded from Massachusetts gross income. Checked 2026-10-12.

Wages

Wages are ordinary income.

2025 Massachusetts Form 1 Instructions, Massachusetts Department of Revenue. Form 1 line 11 deducts the Social Security (FICA), Medicare, railroad and U.S. or Massachusetts retirement contributions each person paid, at most $2,000 per person, not combined or moved between spouses. Checked 2026-10-12.
Topic no. 751, Social Security and Medicare withholding rates (IRS), Internal Revenue Service. The employee's Social Security tax is 6.2% and Medicare tax 1.45% of wages: 7.65%, the rate the engine reads as each person's line 11 amount. Checked 2026-10-12.

Roth conversions

A conversion is taxed as ordinary income in full. It does not draw any retirement-income exclusion.

Source review notes (what the sources do not state outright, or what the engine does not carry):

MA previously-taxed-contribution basis is not modeled (engine taxes the full federally taxable conversion).

Tax treatment of non-government pensions and retirement plans (Massachusetts DOR), Massachusetts Department of Revenue. The taxable part of a traditional-to-Roth conversion included in federal gross income is included in Massachusetts gross income, except for Massachusetts previously taxed contributions. Checked 2026-10-12.

Capital gains

Net long-term gain is taxed as ordinary income.
Net short-term gain (entered as shortTermGains) is taxed at its own 8.5% rate, not the ordinary rate.

Source review notes (what the sources do not state outright, or what the engine does not carry):

The 12% rate on collectibles gains is not modeled (the engine has no collectibles input).
capitalLossCarryover is the state's own carryover; the planner passes the federal one, which understates the later years' state deduction when the state's deduction was smaller (the state tax errs high).
The next year's Massachusetts capital-loss carryover (Schedule B lines 23 and 40, Schedule D line 23) is not calculated: give it as capitalLossCarryover the next year.

Differences Between MA and Federal Tax Law for Personal Income, Massachusetts Department of Revenue. Massachusetts taxes most long-term capital gains at the same 5% rate as ordinary income (collectibles 12% with a 50% deduction; short-term gains 8.5%). Checked 2026-10-12.
Tax rates (Massachusetts DOR), Massachusetts Department of Revenue. Long-term gains are taxed at 5.00%; short-term gains at 8.5%; collectibles at 12.00%; all subject to the 4% surtax above the threshold. Checked 2026-10-12.
Massachusetts tax rates (Mass.gov), Massachusetts Department of Revenue. For tax year 2026 short-term capital gains are taxed at 8.5%. Checked 2026-10-12.
2025 Massachusetts Form 1 Instructions, Massachusetts Department of Revenue. Line 23a taxes the 8.5% income at 0.085; exemptions larger than the 5% income after deductions are applied against the 8.5% income. Checked 2026-10-12.
2025 Schedule B (interest, dividends and certain capital gains), Massachusetts Department of Revenue. Exemptions over Form 1 line 17 (the excess) reduce Schedule B line 35 (interest, dividends and 8.5% short-term gains), with line 38 keeping the interest at 5% first, so the reduction falls on the short-term gains first; not on a separate return. Checked 2026-10-12.
2025 Schedule D (long-term capital gains), Massachusetts Department of Revenue. Excess exemptions left after Schedule B reduce the long-term gain (line 20), only for single, head of household and joint returns. Checked 2026-10-12.
Differences between Massachusetts and federal tax law for personal income, Massachusetts Department of Revenue. Massachusetts lets net capital losses offset up to $2,000 of interest and dividends, never wages or other ordinary income; the rest carries over (engine 1.9.0: cap_loss_limit 2000, cap_loss_investment_only). Checked 2026-10-12.
2025 Form 1 Instructions, Massachusetts Department of Revenue. Massachusetts lets net capital losses offset up to $2,000 of interest and dividends, never wages or other ordinary income; the rest carries over (engine 1.9.0: cap_loss_limit 2000, cap_loss_investment_only). Checked 2026-10-12.
2025 Schedule D, Long-Term Capital Gains and Losses, Massachusetts Department of Revenue. Massachusetts lets net capital losses offset up to $2,000 of interest and dividends, never wages or other ordinary income; the rest carries over (engine 1.9.0: cap_loss_limit 2000, cap_loss_investment_only). Checked 2026-10-12.

Surtaxes and recapture

An extra 4% on taxable income over $1,107,750 (the same threshold for every filing status); the threshold is indexed for inflation.

Massachusetts 4% Surtax on Taxable Income, Massachusetts Department of Revenue. A 4% surtax applies to Massachusetts taxable income above an inflation-indexed threshold of $1,107,750 for tax year 2026. Checked 2026-10-12.

Blindness and disability

An extra exemption of $2,200 for each person who is blind (the filer, and the spouse on a joint return).
The API applies these through its blind, disabled, spouse.blind and spouse.disabled fields; absent means false.

Personal income tax exemptions, Massachusetts Department of Revenue. A $2,200 exemption for each legally blind taxpayer. Checked 2026-10-12.

Part-year and nonresident returns

Part-year resident (Form 1-NR/PY): the tax on the state's own income (what was received while a resident, plus the state-source income while a nonresident), with the deductions and exemptions the form prorates scaled by its ratio (prorated by days).
Nonresident (Form 1-NR/PY): the tax on the state's own income (what was received while a resident, plus the state-source income while a nonresident), with the deductions and exemptions the form prorates scaled by its ratio.
The ratio: the state's own AGI (after its subtractions) of the state's income over the state AGI of the whole year, rounded to 4 places, at most 1.
Prorated on a part-year return: the standard deduction, the personal exemptions, the age-65 subtraction or exemption, dependent exemptions.
Prorated on a nonresident return: the standard deduction, the personal exemptions, the age-65 subtraction or exemption, dependent exemptions.
Part-year: the exemptions × days resident / 365 (four places). Nonresident: × Massachusetts-source income / all income.
A nonresident's retirement income is not taxable by the state (4 U.S.C. §114); the API refuses it in residency.stateIncome. The credit for tax paid to another state and the earned income credits on these returns are not computed.

Married couples whose residency differs (engine 1.13.0)

With residency.spouse on a joint request, each allowed treatment is calculated and reported in residency.couple; tax is the required one, else the state's default, else the couple's residency.election, else the joint return the request's mfj names. Each rule is quoted from the state's instructions (engine 1.14.0: and its statutes, regulations, bulletins and other official guidance) in the sources below.

Spouses	Massachusetts's rule
One spouse a full-year resident, the other a part-year resident	a joint return is required (G.L. c. 62C, 6(a)(2)) unless a spouse has no Massachusetts filing requirement (830 CMR 62.5A.1(11)(a)2.c), when separate returns are allowed; the joint return of these spouses is not calculated (no Massachusetts source describes it), and separate returns are calculated only when the amounts settle that a spouse has no filing requirement; the joint return is not calculated: no Massachusetts source describes the joint return of these spouses: a joint Form 1 is generally not allowed unless both were residents for the same portion of the year, and a joint Form 1-NR/PY unless each reports income for the same resident or nonresident period.
One spouse a full-year resident, the other a nonresident	a joint return is required (G.L. c. 62C, 6(a)(2)) unless a spouse has no Massachusetts filing requirement, or the nonresident spouse has income unrelated to Massachusetts and the couple's Massachusetts income is at most the c. 62, 4(d) threshold (830 CMR 62.5A.1(11)(a)2.c and d.i), when separate returns are allowed; the joint return of these spouses is not calculated (no Massachusetts source describes it); the joint return is not calculated: no Massachusetts source describes the joint return of these spouses: a joint Form 1 is generally not allowed unless both were residents for the same portion of the year, and a joint Form 1-NR/PY unless each reports income for the same resident or nonresident period.
One spouse a part-year resident, the other a nonresident	separate returns is required.
Both part-year residents, different resident periods	separate returns is required.
Both nonresidents, only one with income from the state	a joint part-year / nonresident return, unless the couple elects separate returns.

2025 Form 1-NR/PY Instructions, Massachusetts Department of Revenue. Part-year / nonresident return (engine 1.12.0, residency): Checked 2026-10-12.
2025 Form 1-NR/PY Instructions (Massachusetts Nonresident/Part-Year Resident Income Tax Return), Massachusetts Department of Revenue. Married couples whose residency differs (engine 1.13.0): Checked 2026-10-06.
M.G.L. c. 62C, § 6 (Returns; joint returns) as amended by St. 2023, c. 50, Massachusetts General Court. Married couples whose residency differs (engine 1.13.0): Checked 2026-10-06.
830 CMR 62.5A.1: Non-Resident Income Tax (as amended 1/3/25, new § (11)(a)), Massachusetts Department of Revenue. Married couples whose residency differs (engine 1.13.0): Checked 2026-10-12.
2025 Form 1-NR/PY Instructions (Nonresident or Part-Year Resident Income Tax Return), Massachusetts Department of Revenue. Married couples whose residency differs (engine 1.13.0): Checked 2026-10-06.
2025 Massachusetts Form 1 Instructions (Resident Income Tax Return), Massachusetts Department of Revenue. Married couples whose residency differs (engine 1.13.0): Checked 2026-10-12.

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.

Household (engine inputs)	State tax
Single, 67: $30,000 private pension, $20,000 IRA, $10,000 interest, $24,000 Social Security ($17,000 federally taxable), $5,000 long-term gain	$2,995
Married filing jointly, 70: $40,000 public pension, $40,000 IRA, $20,000 interest, $40,000 Social Security ($34,000 federally taxable), $10,000 long-term gain	$2,990
Single, 60: $60,000 other ordinary income and a $50,000 Roth conversion	$5,280
Married filing jointly, 66: $30,000 IRA, a $40,000 Roth conversion, $30,000 Social Security ($25,500 federally taxable)	$2,990
Single, 58: $36,000 military retirement pay and $30,000 wages	$1,180
Married filing jointly, ages 67 and 61: $50,000 IRA, $10,000 interest, $30,000 Social Security ($25,500 federally taxable), each spouse's age given	$2,525

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.

Single, 67: $30,000 private pension, $20,000 IRA, $10,000 interest, $24,000 Social Security ($17,000 federally taxable), $5,000 long-term gain: $2,995

Line	Amount
Income total used by the income tests	$82,000
+ Other ordinary income in the base	$10,000
+ Retirement income in the base	$50,000
+ Long-term gain in the base	$5,000
− Standard deduction	$4,400
− Age subtractions and deductions	$700
= State taxable income	$59,900
Tax from the rate schedule	$2,995
= Tax before credits	$2,995
= Tax	$2,995

Married filing jointly, 70: $40,000 public pension, $40,000 IRA, $20,000 interest, $40,000 Social Security ($34,000 federally taxable), $10,000 long-term gain: $2,990

Line	Amount
Income total used by the income tests	$144,000
Retirement income and conversions excluded (not in the base)	$40,000
+ Other ordinary income in the base	$20,000
+ Retirement income in the base	$40,000
+ Long-term gain in the base	$10,000
− Standard deduction	$8,800
− Age subtractions and deductions	$1,400
= State taxable income	$59,800
Tax from the rate schedule	$2,990
= Tax before credits	$2,990
= Tax	$2,990

Single, 60: $60,000 other ordinary income and a $50,000 Roth conversion: $5,280

Line	Amount
Income total used by the income tests	$110,000
+ Other ordinary income in the base	$60,000
+ Roth conversion in the base	$50,000
− Standard deduction	$4,400
= State taxable income	$105,600
Tax from the rate schedule	$5,280
= Tax before credits	$5,280
= Tax	$5,280

Married filing jointly, 66: $30,000 IRA, a $40,000 Roth conversion, $30,000 Social Security ($25,500 federally taxable): $2,990

Line	Amount
Income total used by the income tests	$95,500
+ Retirement income in the base	$30,000
+ Roth conversion in the base	$40,000
− Standard deduction	$8,800
− Age subtractions and deductions	$1,400
= State taxable income	$59,800
Tax from the rate schedule	$2,990
= Tax before credits	$2,990
= Tax	$2,990

Single, 58: $36,000 military retirement pay and $30,000 wages: $1,180

Line	Amount
Income total used by the income tests	$66,000
Military pay excluded (not in the base)	$36,000
+ Other ordinary income in the base	$30,000
− Standard deduction	$4,400
− Other subtractions (wage contributions, two-income)	$2,000
= State taxable income	$23,600
Tax from the rate schedule	$1,180
= Tax before credits	$1,180
= Tax	$1,180

Married filing jointly, ages 67 and 61: $50,000 IRA, $10,000 interest, $30,000 Social Security ($25,500 federally taxable), each spouse's age given: $2,525

Line	Amount
Income total used by the income tests	$85,500
+ Other ordinary income in the base	$10,000
+ Retirement income in the base	$50,000
− Standard deduction	$8,800
− Age subtractions and deductions	$700
= State taxable income	$50,500
Tax from the rate schedule	$2,525
= Tax before credits	$2,525
= Tax	$2,525

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 Massachusetts's law moves it. Rates and the rules themselves stay the 2026 ones (how projection works).

Amounts (engine fields)	After 2026	What the law says, and the source
`std_deduction_single`, `std_deduction_mfj`, `std_deduction_hoh`, `dep_exemption`, `senior_subtraction_single`, `senior_subtraction_mfj`, `blind_exemption`	Fixed in law: held at the rules-year amount in every later year.	The personal exemption could grow only by revenue-triggered $275 steps and 'shall not exceed' $4,400 (single) / $6,800 (HOH) (joint $8,800), which it has reached; the $1,000 dependent, $700 age-65 and $2,200 blind exemptions are nominal. No inflation indexing in c. 62 § 3(B)(b). M.G.L. c. 62, § 3 (Internet Archive capture of malegislature.gov) (Massachusetts General Court, statute): § 3(B)(b) exemptions and caps. Quoted: "the personal exemption shall not exceed $4,400"; "the personal exemption shall not exceed $6,800"; "an exemption of one thousand dollars for each individual who qualifies for exemption as a dependent"; "an additional exemption of seven hundred dollars if the taxpayer had attained the age of sixty-five before the close of his taxable year". Checked 2026-09-30.
`senior_subtraction_min_age`	Attained age: the same age in every year.	Fixed attained age: 65 before the close of the taxable year. M.G.L. c. 62, § 3 (Internet Archive capture of malegislature.gov) (Massachusetts General Court, statute): Age wording. Quoted: "had attained the age of sixty-five before the close of his taxable year". Checked 2026-09-30.
`top_surtax_threshold`	Indexed: C-CPI-U cost-of-living adjustment as for federal brackets (IRC 1(f)(3)), base 2022; increases only; the increase rounded down to a multiple of $50.	The 4% surtax threshold ($1,000,000 from 2023) is adjusted annually for cost-of-living increases 'by the same method used for federal income tax brackets' (IRC 1(f): C-CPI-U, increases rounded down to $50); increases only. $1,107,750 for 2026. Massachusetts Constitution, Amendment Art. XLIV as amended by Art. CXXI (Fair Share surtax) (Internet Archive capture) (Massachusetts General Court, statute): The $1,000,000 surtax level is adjusted annually for cost-of-living increases by the federal bracket method. Quoted: "this $1,000,000 (one million dollars) income level shall be adjusted annually to reflect any increases in the cost of living by the same method used for federal income tax brackets". Checked 2026-10-12. 26 U.S.C. 1 (Tax imposed), subsection (f)(7) (Legal Information Institute (Cornell) - U.S. Code, federal): IRC 1(f)(7)(A): increases under 1(f)(2)(A) (brackets), 63(c)(4) (standard deduction) and 151(d)(4) are rounded down to a multiple of $50. Quoted: "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". Checked 2026-10-12.
`wage_contrib_deduction_max`	Fixed in law: held at the rules-year amount in every later year.	FICA/RRTA and public-retirement contributions deducted from wages are capped at $2,000 per taxpayer; nominal, no indexing. M.G.L. c. 62, § 3 (Internet Archive capture of malegislature.gov) (Massachusetts General Court, statute): § 3(B)(a)(3)-(4). Quoted: "attributable to any one taxpayer exceed two thousand dollars". Checked 2026-09-30.
`no_tax_status_single`, `no_tax_status_hoh`, `no_tax_status_mfj`, `nts_per_dependent`, `limited_income_limit_single`, `limited_income_limit_hoh`, `limited_income_limit_mfj`, `lic_limit_per_dependent`	Fixed in law: held at the rules-year amount in every later year.	No tax if Massachusetts AGI is at most $8,000 (single) or $7,600 plus the personal and dependent exemptions (joint/HOH); the limited income credit caps tax at 10% of AGI over that threshold up to 1.75 times the threshold. All derived from fixed amounts; § 5 has no indexing. M.G.L. c. 62, § 5 (Internet Archive capture of malegislature.gov) (Massachusetts General Court, statute): § 5(a). Quoted: "in the case of a single person, eight thousand dollars"; "seven thousand six hundred dollars plus the deductions allowed"; "shall not apply in any case where massachusetts adjusted gross income exceeds one hundred and seventy-five hundredths of the aforementioned threshold". Checked 2026-09-30.
`cap_loss_limit`, `cap_loss_limit_mfs`	Fixed in law: held at the rules-year amount in every later year.	Massachusetts allows at most $2,000 of Part A/Part C capital loss against Part A interest and dividends (same for MFS); nominal, no indexing. M.G.L. c. 62, § 2 (Internet Archive capture of malegislature.gov) (Massachusetts General Court, statute): § 2(c) Part A capital loss limit. Quoted: "not more than an aggregate amount of $2,000 in part a capital loss and part c capital loss shall be applied against any interest and dividends". Checked 2026-10-12.
`ma-senior-circuit-breaker` (a table held in code)	Indexed: Massachusetts inflation adjustment of the circuit breaker amounts; the increase rounded to the nearest $1. The engine carries the 2025 figure (the latest published) for 2026, so a projection adds 1 year of indexing at the factor's average annual rate.	The Senior Circuit Breaker's maximum credit and income and value limits are adjusted annually for inflation (M.G.L. c. 62 s. 6(k)); the engine carries the 2025 amounts, the 2026 ones not yet published. 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (Massachusetts Department of Revenue, instructions): Senior Circuit Breaker Credit (Schedule CB) - refundable credit for 65+ homeowners (real estate tax + 50% water/sewer) or renters (25% of rent) exceeding 10% of total income Quoted: "must be at least 65 years of age before January 1, 2026 to qualify for this credit"; "If over $1,298,000,". Checked 2026-10-01. 2025 Massachusetts Form 1 Instructions (Wayback copy) (Massachusetts Department of Revenue, instructions): Senior Circuit Breaker Credit (Schedule CB) - refundable credit for 65+ homeowners (real estate tax + 50% water/sewer) or renters (25% of rent) exceeding 10% of total income Quoted: "or 25% of their rent"; "The maximum credit for tax year 2025 is $2,820.". Checked 2026-10-01.
`rent_ded_cap`, `rent_ded_cap_mfs`	Fixed in law: held at the rules-year amount in every later year.	M.G.L. c. 62 s. 3(B)(a)(9) caps the rental deduction at $4,000 as a dollar amount with no adjustment clause ($2,000 on a separate return per the Form 1 instructions): fixed in law. M.G.L. c. 62 s. 3 (Internet Archive copy) (Massachusetts Legislature, statute): 3(B)(a)(9). Quoted: "provided, however, that such deduction shall not exceed $4,000 for a single person". Checked 2026-10-01.

Enacted for later years, not applied by the projection

None found: the research found no change enacted for years after 2026 beyond the schedules above.

What the engine does not calculate, and known approximations

The line 22 tax table (line 21 up to $24,000) is not used; the engine applies 5% to the exact amount (at most $1.50 from the table).
ordinaryIncome is read as Schedule B interest and dividends: exemptions offset the 5% income of Form 1 line 17 (wages, pensions, IRA dollars, conversions) first; on single, head-of-household and joint returns what is left reduces the 8.5% short-term gains, then the interest and dividends, then long-term gains; on a separate return it is lost (engine 1.8.0).
MA previously-taxed-contribution basis is not modeled (engine taxes the full federally taxable conversion). (Roth conversions)
The 12% rate on collectibles gains is not modeled (the engine has no collectibles input). (Capital gains)
The next year's Massachusetts capital-loss carryover (Schedule B lines 23 and 40, Schedule D line 23) is not calculated: give it as capitalLossCarryover the next year. (Capital gains)
The child and family tax credit is refundable and is not calculated. Sources: Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01).
The separate rate on collectibles gains, and the line 11 deduction for self-employment tax and public-retirement-system contributions (wages are read as FICA wages), are not calculated. Sources: Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12); Tax rates (Massachusetts DOR) (checked 2026-10-12); Massachusetts tax rates (Mass.gov) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Schedule B (interest, dividends and certain capital gains) (checked 2026-10-12); 2025 Schedule D (long-term capital gains) (checked 2026-10-12); Differences between Massachusetts and federal tax law for personal income (checked 2026-10-12); 2025 Form 1 Instructions (checked 2026-10-12); 2025 Schedule D, Long-Term Capital Gains and Losses (checked 2026-10-12).
Contributions already taxed by Massachusetts are not recovered: IRA, Keogh and Roth-conversion distributions (Schedule X line 2 worksheet) and contributory private-pension and 403(b) distributions (Form 1 line 4) are taxed at the federally taxable amount. The iraBasis input is not read for Massachusetts: the Massachusetts basis (every contribution Massachusetts taxed, recovered before any distribution is taxed) is not the federal after-tax basis. Sources: Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12).
pensionPublic is read as a Massachusetts or federal contributory pension (exempt). A contributory pension from another state is deductible only where that state exempts Massachusetts pensions (Schedule Y line 13), and noncontributory public pensions, 457 and TSP distributions are taxable: enter those as pensionPrivate, iraDistributions or employerPlanDistributions. Sources: Tax treatment of government pensions (Massachusetts DOR) (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12).
Qualified charitable IRA distributions (Schedule X line 2 worksheet line 6) and interest on U.S. obligations (Schedule B line 6a) have no input: leave them out of iraDistributions and ordinaryIncome. Sources: Massachusetts tax information for seniors and retirees (checked 2026-10-12); Differences Between MA and Federal Tax Law for Personal Income (checked 2026-10-12).
The medical/dental exemption (Form 1 line 2e) is not calculated: it is allowed only to a filer who itemizes on the federal return, which is not an input. The adoption exemption (line 2f) and the Schedule Y deductions need amounts the inputs do not carry and are not calculated; the rental deduction (line 14) is calculated (engine 1.12.0). Sources: Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01).
The health care penalty for a person without Massachusetts minimum creditable coverage (Form 1 line 35, Schedule HC) is not calculated. Sources: Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01).
The Senior Circuit Breaker credit reads propertyTaxPaid as the real estate tax after abatements and exemptions; the half of water and sewer charges the schedule adds, and the rules for a home owned or rented part of the year, are not inputs. Sources: Personal income tax exemptions (Massachusetts DOR) (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-12); 2025 Massachusetts Form 1 Instructions (checked 2026-10-01); 2025 Schedule CB Circuit Breaker Credit (Wayback copy; mass.gov blocks scripted access) (checked 2026-10-01); Massachusetts 2025 Form 1 Instructions (checked 2026-10-12); Massachusetts 2025 Form 1 Resident Income Tax Return (checked 2026-10-12); General Laws Part I Title IX Chapter 62 Section 3 (malegislature.gov) (checked 2026-10-01).
Married couples whose residency differs (engine 1.13.0): when one spouse is a full-year resident and the other a part-year resident, the joint return is not calculated: no Massachusetts source describes the joint return of these spouses: a joint Form 1 is generally not allowed unless both were residents for the same portion of the year, and a joint Form 1-NR/PY unless each reports income for the same resident or nonresident period; when one spouse is a full-year resident and the other a nonresident, the joint return is not calculated: no Massachusetts source describes the joint return of these spouses: a joint Form 1 is generally not allowed unless both were residents for the same portion of the year, and a joint Form 1-NR/PY unless each reports income for the same resident or nonresident period. Sources: 2025 Form 1-NR/PY Instructions (checked 2026-10-12); 2025 Form 1-NR/PY Instructions (Massachusetts Nonresident/Part-Year Resident Income Tax Return) (checked 2026-10-06); M.G.L. c. 62C, § 6 (Returns; joint returns) as amended by St. 2023, c. 50 (checked 2026-10-06); 830 CMR 62.5A.1: Non-Resident Income Tax (as amended 1/3/25, new § (11)(a)) (checked 2026-10-12); 2025 Form 1-NR/PY Instructions (Nonresident or Part-Year Resident Income Tax Return) (checked 2026-10-06); 2025 Massachusetts Form 1 Instructions (Resident Income Tax Return) (checked 2026-10-12).

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 Form 1 replayed line by line (2025 Form 1 and instructions with the TY2026 4% surtax threshold of $1,107,750): exemptions lines 2a-2d, exempt contributory/military pensions line 4, Schedule X line 2 IRA and conversions, lines 11a/11b, the line 22 tax table and 5% rate, Schedule B 8.5% income, Schedule D line 24, No Tax Status and the Limited Income Credit, Schedule 4% Surtax; 22 scenarios asserted in test_state_worksheets_2.c (the 5 group-2 findings resolved by engine 1.6.0), every Form 1 line mapped in research/data/state-tax-form-map/MA.json, 2 open findings (excess exemptions, fm3-MA-01/02).

Golden scenarios (hand-computed expected tax, asserted to within $1): none for this state.
State-specific unit tests: test_none_state_taxes_pension_like_ordinary, test_credit_programs_2, test_ma, test_ma_line11, test_ma_short_term_rate, test_ma_nts_lic, test_applied, test_spouse_share_clamps_c, test_s2_ma_order, test_wages_ordinary_elsewhere, test_c_states, test_days, test_ma_hoh_senior_public_pension.
Structural tests covering every state: 10.
State forms and worksheets followed in the test derivations: Form 1 (2025) lines 2a, 2c, 3, 4, 9, 10, 11a/11b, 16-22, 23a, 24, 27, 28a, 28b, 29; Form 1 tax table at the 5.0% rate (line 21 up to $24,000); Schedule X line 2 worksheet (IRA/Keogh and Roth conversion distributions); Schedule D line 24 (long-term gains at 5%); Schedule 4% Surtax (TY2026 threshold $1,107,750); Line 27 Massachusetts AGI worksheet (No Tax Status); Line 29 Limited Income Credit worksheet; backend/tests/test_state_worksheets_2.c.