What This Page Is For
Every number on this site comes from one tax engine: the calculators, the worked examples, the state tables and the rankings. This page explains how that engine works, where its figures come from, what it deliberately leaves out, and what has been corrected and when. If a figure on any page looks wrong to you, this is where to check it, and the contact page is where to tell me.
Last reviewed October 7, 2026. Maintained by Rahul B.
The Calculation, Step by Step
For a given net profit, filing status and state, the engine does the following, in this order.
- Net profit is gross 1099 income minus business expenses.
- Self-employment tax is charged on 92.35% of net profit: 12.4% Social Security up to the $184,500 wage base, 2.9% Medicare on all of it, and the 0.9% Additional Medicare Tax above $200,000 ($250,000 for joint filers).
- Adjusted gross income is net profit, minus half of the self-employment tax, plus any other income entered.
- Federal taxable income is AGI minus the 2026 standard deduction: $16,100 single, $32,200 married filing jointly, $24,150 head of household.
- Federal income tax runs that amount through the 2026 brackets, from 10% to 37%.
- State income tax starts from federal AGI in most states, subtracts the state's own deduction and exemption, applies the state's brackets, and then subtracts any personal credit. The table below shows what is applied for each state.
- Quarterly payment is the annual total divided by four. The state pages split it into the federal and state shares, because they are paid to different agencies.
Each state page shows this working line by line for the income you enter, so you can follow the state calculation and not just read the answer.
Where the Numbers Come From
- Federal brackets and standard deduction: IRS Revenue Procedure 2025-32.
- Self-employment tax: the IRS self-employment tax rules and the Social Security Administration's 2026 wage base.
- State brackets, deductions and exemptions: the Tax Foundation's 2026 state individual income tax table as the baseline, checked against each state's own tax agency.
- Mid-year law changes: the signed bill or the state agency's notice. The Tax Foundation table is fixed as of January 1, so it does not show rate cuts that a legislature passes in the spring and backdates to the start of the year. In 2026 five states did exactly that.
Where a national table and a state agency disagree, the state agency wins. Maine is the 2026 example: the national table lists a $8,350 standard deduction, and Maine Revenue Services published $15,300.
What the Engine Models for Each State
Rates are the lowest and highest that apply to a single filer in 2026. "Also modelled" lists anything beyond plain brackets.
| State | 2026 rates | Starts from | Deduction, single | Exemption or credit, single | Also modelled |
|---|---|---|---|---|---|
| Alabama | 2% to 5% | Federal AGI | $3,000 | $1,500 exemption | local tax flagged, not computed |
| Alaska | No tax on earned income | – | – | – | – |
| Arizona | 2.5% flat | Federal AGI | $16,100 | – | – |
| Arkansas | 2% to 3.7% | Federal AGI | $2,470 | $29 credit | first $5,600 taxed at 0%; second table above $94,700 |
| California | 1% to 13.3% | Federal AGI | $5,540 | $153 credit | – |
| Colorado | 4.4% flat | Federal AGI | $16,100 | – | – |
| Connecticut | 2% to 6.99% | Federal AGI | – | $15,000 exemption | exemption phase-out |
| Delaware | 2.2% to 6.6% | Federal AGI | $3,250 | $110 credit | first $2,000 untaxed; local tax flagged, not computed |
| Florida | No tax on earned income | – | – | – | – |
| Georgia | 4.99% flat | Federal AGI | $15,000 | – | – |
| Hawaii | 1.4% to 11% | Federal AGI | $4,400 | $1,144 exemption | – |
| Idaho | 5.3% flat | Federal AGI | $16,100 | – | first $4,811 taxed at 0% |
| Illinois | 4.95% flat | Federal AGI | – | $2,925 exemption | – |
| Indiana | 2.95% flat | Federal AGI | – | $1,000 exemption | local tax flagged, not computed |
| Iowa | 3.8% flat | Federal AGI | $16,100 | $40 credit | local tax flagged, not computed |
| Kansas | 5.2% to 5.58% | Federal AGI | $3,605 | $9,160 exemption | – |
| Kentucky | 3.5% flat | Federal AGI | $3,360 | – | local tax flagged, not computed |
| Louisiana | 3% flat | Federal AGI | $12,875 | – | – |
| Maine | 5.8% to 7.15% | Federal AGI | $15,300 | $5,300 exemption | deduction phase-out |
| Maryland | 2% to 6.5% | Federal AGI | $3,350 | $3,200 exemption | local tax flagged, not computed |
| Massachusetts | 5% to 9% | Federal AGI | – | $4,400 exemption | – |
| Michigan | 4.25% flat | Federal AGI | – | $5,900 exemption | local tax flagged, not computed |
| Minnesota | 5.35% to 9.85% | Federal AGI | $15,300 | – | – |
| Mississippi | 4% flat | Federal AGI | $2,300 | $6,000 exemption | first $10,000 taxed at 0% |
| Missouri | 2% to 4.7% | Federal AGI | $16,100 | – | first $1,348 taxed at 0%; local tax flagged, not computed |
| Montana | 4.7% to 5.65% | Federal AGI | $16,100 | – | – |
| Nebraska | 2.46% to 4.55% | Federal AGI | $8,850 | $176 credit | – |
| Nevada | No tax on earned income | – | – | – | – |
| New Hampshire | No tax on earned income | – | – | – | – |
| New Jersey | 1.4% to 10.75% | Net business profit | – | $1,000 exemption | – |
| New Mexico | 1.5% to 5.9% | Federal AGI | $16,100 | – | – |
| New York | 3.9% to 10.9% | Federal AGI | $8,000 | – | local tax flagged, not computed |
| North Carolina | 3.99% flat | Federal AGI | $12,750 | – | – |
| North Dakota | 1.95% to 2.5% | Federal AGI | $16,100 | – | first $48,475 taxed at 0% |
| Ohio | 3% flat | Net business profit | – | – | first $250,000 taxed at 0%; local tax flagged, not computed |
| Oklahoma | 2.5% to 4.5% | Federal AGI | $6,350 | $1,000 exemption | first $3,750 taxed at 0% |
| Oregon | 4.75% to 9.9% | Federal AGI | $2,910 | $256 credit | local tax flagged, not computed |
| Pennsylvania | 3.07% flat | Net business profit | – | – | local tax flagged, not computed |
| Rhode Island | 3.75% to 5.99% | Federal AGI | $11,200 | $5,250 exemption | – |
| South Carolina | 1.99% to 5.21% | Federal AGI | $15,000 | – | deduction phase-out |
| South Dakota | No tax on earned income | – | – | – | – |
| Tennessee | No tax on earned income | – | – | – | – |
| Texas | No tax on earned income | – | – | – | – |
| Utah | 4.45% flat | Federal AGI | – | $966 credit | credit phase-out |
| Vermont | 3.35% to 8.75% | Federal AGI | $7,650 | $5,300 exemption | – |
| Virginia | 2% to 5.75% | Federal AGI | $8,750 | $930 exemption | – |
| Washington | No tax on earned income | – | – | – | – |
| Washington D.C. | 4% to 10.75% | Federal AGI | $16,100 | – | – |
| West Virginia | 2.11% to 4.58% | Federal AGI | – | $2,000 exemption | local tax flagged, not computed |
| Wisconsin | 3.5% to 7.65% | Federal AGI | $13,960 | $700 exemption | deduction phase-out |
| Wyoming | No tax on earned income | – | – | – | – |
What It Leaves Out
The engine is a planning tool, and some real rules are outside it. Where one of them matters for a state, that state's page says so. The main omissions:
- The qualified business income deduction. Most sole proprietors qualify for it, so real federal tax is usually lower than the estimate. Idaho and North Dakota also pass it through to the state return.
- Tax credits other than each state's basic personal credit: child credits, earned income credits, education credits and the rest.
- Local income and earnings taxes. Ohio and Kentucky cities, Maryland and Indiana counties, New York City, Philadelphia, Wilmington, Kansas City and St. Louis all tax freelance profit. The calculator flags that a local tax exists and does not compute it.
- Itemized deductions. Everyone is assumed to take the standard deduction.
- State rules that depend on facts the calculator does not ask for. Examples: Alabama's deduction for federal income tax paid, North Carolina's depreciation add-back, Connecticut's benefit recapture above $200,000, Rhode Island's deduction phase-out above $261,000, and Vermont's 0.11% Child Care Contribution.
- Gross receipts, franchise and sales taxes such as Washington's B&O tax, Hawaii's General Excise Tax, New Mexico's Gross Receipts Tax and state LLC fees. The state pages describe them; the calculator does not add them.
- Part-year and multi-state residency. The result assumes you lived in one state all year.
Leaving out the QBI deduction and most credits means the estimate tends to run high. That is deliberate. Setting aside slightly too much is a better mistake than setting aside too little.
Changelog
Every change to the engine, and every correction to a published figure, is recorded here with the date it went live.
October 7, 2026
- South Carolina: replaced the 0%, 3% and 6% schedule with the 1.99% and 5.21% rates and the new income adjusted deduction from Act 110, signed March 30, 2026 and effective for all of 2026. The bill at $75,000 of profit fell from $3,025 to $2,306.
- Georgia: rate lowered from 5.19% to 4.99% and standard deduction raised from $12,000 to $15,000, following House Bill 463, signed in May 2026.
- Utah: rate lowered from 4.5% to 4.45% (Senate Bill 60). Also added the phase-out of the taxpayer tax credit, which the engine had been ignoring. That omission understated Utah tax by roughly $670 at $75,000 of profit.
- Arkansas: top rate lowered from 3.9% to 3.7% (2026 special session), and the lower-income tax table and bracket adjustment added. The engine had been applying the higher-income table to everyone.
- West Virginia: all five rates lowered by about 5% (Senate Bill 392), now 2.11% to 4.58%.
- Maine: standard deduction corrected from $8,350 to the $15,300 Maine Revenue Services published for 2026, and the phase-out above $102,250 added. The bill at $75,000 fell by about $470.
- Arizona: standard deduction changed from $8,350 to the federal $16,100, in line with the state's 2025 forms. Arizona's conformity legislation for 2026 was still unresolved on this date, and the Arizona page says so.
- All 51 state pages: each now has its own calculator, fixed to that state, which shows the state computation line by line and compares nearby states.
- 22 state pages rewritten around the rules specific to that state, each checked against the state's tax agency.
- Ranking pages, the rate-by-state dataset and the downloadable CSV regenerated from the corrected engine.
September 22, 2026
- Idaho: the first $4,811 of taxable income is exempt. The engine had been taxing it, overcharging by about $255.
- Federal: the head-of-household 32% bracket threshold corrected from $201,775 to $201,750.
- The rate-by-state page was not drawing its table on load. Fixed, and its dataset regenerated.
- Mileage rate updated to the two 2026 rates, 72.5 cents to June 30 and 76 cents from July 1. Retirement plan limits updated to 2026: $24,500 elective deferral and $72,000 total.
- Figures on 27 state pages, the burden study and the best-states table brought back in line with the engine after the September 21 changes.
September 21, 2026
- Ohio: added the Business Income Deduction, which exempts the first $250,000 of business income. The engine had been taxing it.
- Wisconsin: added the sliding-scale standard deduction, which shrinks as income rises.
- Connecticut: added the personal exemption phase-out. The engine had been granting the full $15,000 at every income.
August 8, 2026
- Tax agency names corrected on 23 state pages. Not every state calls its agency a Department of Revenue.
Found a Mistake?
I am a software developer, not a CPA, and tax law changes during the year. If a number here disagrees with your state's own publication, please send me the source. Confirmed corrections are applied to the engine and logged above.