Methodology and 51-Source Ledger
Every rate, bracket and filing rule on IncomeTaxByState.com traces to a published source: each state's own Department of Revenue or Tax Commission, plus IRS Publication 17, the Tax Foundation State Business Tax Climate Index, the Federation of Tax Administrators, the NCSL State Tax Actions report, and the US Bureau of Labor Statistics for income-level reference points. This page documents the full 51-state DOR ledger with statute citations, the federal and aggregator cross-checks, the calculation framework, and the refresh cadence per source layer.
Federal sources (IRS + IRC)
Federal baseline: IRS Publication 17, the annual IRS Notice setting inflation-adjusted thresholds, and the Internal Revenue Code provisions states conform to or modify. Cited on the home page and every page that explains marginal-vs-effective rate.
| Source | What we take from it | Verified |
|---|---|---|
| IRS Publication 17: Your Federal Income Tax (For Individuals) | Federal AGI definitions, standard deduction, filing status thresholds, federal-state interaction references (state itemized deduction conformity, federal deductibility of state tax). | 2026-05-28 |
| IRS Notice 2025-67: 2026 Inflation Adjustments | Federal inflation-adjusted thresholds for 2026 (federal standard deduction, brackets, retirement limits). Reference baseline for states that conform to the federal code. | 2026-05-28 |
| IRS Statistics of Income: Individual Statistical Tables by State | Historical federal AGI distribution and effective tax rate by state. Used for cross-validation of the representative income brackets ($50K/$75K/$100K/$250K). | 2026-05-28 |
| IRS State Government Websites Directory | IRS-maintained canonical directory of each state revenue department; the entry point for primary-source verification per state. | 2026-05-28 |
| United States Code Title 26 (Internal Revenue Code) | Federal statutory framework that states conform to or modify. Key sections cited: IRC § 62 (above-the-line deductions), § 63 (standard deduction), § 151 (personal exemption, suspended through 2025). | 2026-05-28 |
Aggregator and think-tank cross-checks
Six independent aggregator sources used to cross-validate the 51 state DOR publications. The Tax Foundation Climate Index is the primary autumn-release cross-check; the FTA table is the legislative-tracking cross-check; NCSL is the legislative-session tracker.
| Source | What we take from it | Verified |
|---|---|---|
| Tax Foundation State Business Tax Climate Index 2026 | Annual independent ranking of all 50 states on the individual income tax, corporate tax, sales tax, property tax, and unemployment-insurance tax components. Used as the cross-check for rates and structural classification (flat vs graduated vs none). | 2026-05-28 |
| Tax Foundation State Individual Income Tax Rates and Brackets | Per-state bracket schedule with effective dates and legislative-change annotation. Cross-check against the state's own DOR publication. | 2026-05-28 |
| Federation of Tax Administrators: State Individual Income Tax Rates and Brackets | Industry-association reference for state bracket schedules, maintained by state DOR contributors. Cross-validates the Tax Foundation table. | 2026-05-28 |
| NCSL State Tax Actions 2025 | Legislative tracking by the National Conference of State Legislatures. Flags mid-year rate changes, effective dates, and legislative status of pending rate-reduction glide paths. | 2026-05-28 |
| Tax Policy Center (Urban-Brookings) State Tax Data | Think-tank comparative state-tax data with historical trends; used for the marginal-vs-effective rate explainers and historical-rate cross-references. | 2026-05-28 |
| AICPA Tax Practice Resources | Professional cross-reference for technical interpretation of state tax rules and conformity to federal code. | 2026-05-28 |
The 51-state Department of Revenue ledger
Every state plus DC: the primary Department of Revenue or Tax Commission, the URL we verify the bracket schedule against, the statutory citation establishing the state's income tax authority, and the date of last verification. This ledger is the substantive moat. Aggregators (Tax Foundation, FTA) reflect changes after the state DOR publishes them, never before.
Total: 51 rows (50 states + DC). Each row corresponds to one JSON file in /web/data/states/{slug}.json, which carries the bracket schedule, standard deduction, personal exemption, local-income-tax detail, reciprocity list, retirement-income flags, and the per-state sources array.
Source-verification cadence
Each source layer has a different refresh rhythm. Federal IRS publications drop in late November after Treasury finalises inflation adjustments. The Tax Foundation Climate Index releases each autumn. State DOR rate publications gazette in the November-January window for the following tax year. States with active rate-reduction glide paths (Mississippi, Iowa, Georgia, NC, Kentucky, Louisiana) are hash-checked quarterly because mid-year legislative changes are possible.
| Source layer | Cadence | Trigger |
|---|---|---|
| IRS Publication 17 and IRS Notice (federal baseline) | Annual, January | IRS posts current-year publication once inflation adjustments finalise (Notice 2025-67 published 2025-11-13 for tax year 2026). |
| Tax Foundation State Business Tax Climate Index | Annual, mid-October | Tax Foundation publishes the next year's index each autumn. |
| Federation of Tax Administrators rate table | Continuous; annual roll-up January | Updated as state legislatures pass new bracket schedules; FTA aggregates per-state submissions. |
| NCSL State Tax Actions | Continuous | Tracked per state legislative session; annual State Tax Actions report published each spring. |
| State DOR (settled rate, no recent legislation) | Annual, November-January | Most states gazette inflation-indexed bracket schedules by mid-November for the following tax year. |
| State DOR (active rate-reduction glide path) | Quarterly hash-check | Mississippi (4.4% to 3.5% by 2030), Iowa (3.9% post-2026 reform), Georgia (4.99% in 2026 to 3.99%), North Carolina (3.99%), Kentucky (4.0% to 3.5%), Louisiana — diff-scanned for mid-year changes. |
Calculation framework
Marginal vs effective rate
Every per-state page applies brackets only to the income within each bracket, never to total income. The effective rate is total state tax divided by gross income (not taxable income), expressed as a percentage. Worked examples show the bracket-by-bracket build-up so any reader can audit the arithmetic against the state DOR's published bracket table. Same bracket-build mechanic IRS Publication 17 Chapter 1 documents for federal tax.
Standard deduction handling
Most state calculators apply the state's own standard deduction before the bracket math. Some states (Illinois, Indiana, Massachusetts, Michigan) use a personal exemption instead. Some states (Pennsylvania per 72 P.S. § 7302) allow neither a standard deduction nor a personal exemption. Each state's JSON file in /data/states/{slug}.json documents which mechanism applies and the 2026 figure, sourced from the state DOR's current-year filing instructions.
Flat vs graduated
14 states use a flat rate (one rate on all taxable income). 27 states plus DC use graduated brackets. 9 states levy no personal income tax. The /flat-tax-states, /graduated-rate-states and /no-income-tax-states pages group all 50 by structure. Massachusetts is hybrid: 5% flat plus a 4% surtax on income above $1M (the Fair Share Amendment, Mass. Const. art. CXII).
Local income tax stacking
16 states allow city or county income taxes that stack on top of the state rate. We document the largest local taxing authorities per state: NYC (3.078% to 3.876% per N.Y. Tax Law § 1304), Yonkers (16.75% state-tax surcharge), Philadelphia (3.75% resident / 3.44% non-resident per 72 P.S. § 7302), Detroit (2.4% / 1.2% per MCL § 141.601), all 23 Maryland counties + Baltimore City (1.75% to 3.20% per Md. Code Ann., Tax-Gen. § 10-103), all 92 Indiana counties per Ind. Code § 6-3.6, 600+ Ohio municipalities per Ohio Rev. Code § 718. See /local-income-tax for the full reference.
Reciprocity agreements
16 states have bilateral reciprocity agreements that let residents of one state work in another and pay only home-state income tax. The most important: NJ-PA (1977, oldest US reciprocity, per N.J.A.C. 18:35-5.1 and 72 P.S. § 7301), DC-MD-VA-WV cluster, Ohio reciprocity with Indiana / Kentucky / Michigan / Pennsylvania / West Virginia. New York applies the convenience-of-employer rule per N.Y. Tax Law § 631 and TSB-M-06(5)I, which can override reciprocity expectations.
Residency tests
Each state defines residency differently. California uses a domicile test per Cal. Rev. & Tax. Code § 17014. New York uses a 183-day statutory residence rule plus domicile per N.Y. Tax Law § 605. Most states use a 183-day default. We surface the residency rule on each state page because it determines whether worldwide income or just state-source income is taxed.
In scope
- Statutory state income tax brackets and rates as published by each state DOR.
- State standard deduction, personal exemption and filing status thresholds.
- Effective rate calculations at $50K / $75K / $100K / $250K reference incomes (single filer, standard deduction).
- Local income taxes that stack on top of the state rate (cities, counties, school districts).
- Retirement income treatment (Social Security, pensions, 401(k), IRA, military pension).
- Filing rules for residents, part-year residents and non-residents, plus the 16 active reciprocity agreements.
Out of scope
- Federal income tax calculations beyond noting state conformity (see effectivetaxratecalculator.com).
- FICA (Social Security and Medicare withholding) calculations (see aftertaxincomecalculator.com).
- Property tax, sales tax and other non-income state taxes beyond brief context on no-tax states.
- Itemized deductions: we use standard deduction in worked examples because that is the default for most taxpayers.
- State credits (earned income credit, child credit, education credit, etc.): noted where material, not exhaustively listed.
- Estate, inheritance and gift taxes at the state level.
YMYL limitations and disclaimers
Income tax filing is Your Money Your Life territory. Material errors carry real penalties and back-tax exposure. This site is a reference, not advice. Calculator outputs apply standard deduction and the state's published brackets; they do not capture itemized deductions, state credits, federal-state interactions, residency edge cases, multi-state filing or self-employment tax.
Before filing, always:
- Confirm current-year rates with your state Department of Revenue's own publication.
- Consult a licensed CPA, Enrolled Agent or tax attorney for advice on your specific circumstances, especially for multi-state, high-income, business-owner, retirement-transition or convenience-of-employer situations.
- Read the IRS instructions for the current tax year for federal-state interaction questions.
If a figure on this site disagrees with the state DOR's own publication, the state DOR is authoritative. Email [email protected] with the URL and the discrepancy; we correct errors within 5 business days. See also /disclaimer for the full not-tax-advice statement.
Not published on this site
- Specific tax preparation advice for individual circumstances.
- Estimates that bake in itemized deductions, state-specific credits or federal-state interaction edge cases.
- Forecasts of future rate changes beyond what state legislatures have already enacted into law with a published effective date.
- State-by-state comparison rankings, beyond the structural sort by top rate or effective rate.
- Tax-software vendor reviews; affiliate links to TurboTax, TaxAct and FreeTaxUSA are present but are not editorial recommendations.
Last reviewed June 2026; dataset stamp 2026-05-28. Read more about who builds this →