How These Calculators Work

Step 1 — Self-employment tax

Self-employment tax is charged on 92.35% of your net profit, not all of it. That reduced figure is your net earnings from self-employment.

The Social Security half stops at the wage base of $184,500. The Medicare half does not stop. This is why a freelancer earning $1,000,000 does not owe 15.3% of it in self-employment tax — a detail a surprising number of calculators get wrong.

Step 2 — Half of that comes back off your income

You deduct 50% of your self-employment tax when working out income tax. It is subtracted from your income before the standard deduction, not from the tax itself.

Step 3 — The standard deduction

Whatever is left after this is your taxable income.

Step 4 — Federal income tax, bracket by bracket

Brackets are marginal. Earning one dollar into a higher bracket taxes that dollar at the higher rate, not your whole income. These are the 2026 single-filer bands the calculators walk through:

Married-filing-jointly and head-of-household bands are in the same source document and are used when you change filing status.

Step 5 — State tax, and its honest limits

Your state's rate is applied as a single percentage of taxable income. Nine states levy no income tax at all, and those return zero. For a selection with no rate in the table — District of Columbia — the calculators fall back to the 4.83% average across the fifty states rather than inventing a figure.

This is the weakest step in the chain, and worth knowing before you rely on it: states with progressive brackets are approximated by one rate.

Mileage

2026 has two business mileage rates, which is unusual — the IRS changed it mid-year:

• 2026-01-01 to 2026-06-30 — 72.5¢ per mile
• 2026-07-01 to 2026-12-31 — 76.0¢ per mile

What these calculators do not do

This is the part most calculators leave out. Every item below is a real gap between an estimate here and the return you will actually file.

State tax brackets

Each state's rate is applied as a single percentage, not through its own brackets. States with progressive rates will be over- or understated depending on your income, and city taxes are only included where a page says so.

Tax credits

No credits are applied — not the Child Tax Credit, the Earned Income Credit, education credits or energy credits. Credits reduce tax directly, so a real return can come out substantially lower than these estimates.

The QBI deduction's limits

Where a page shows a Qualified Business Income deduction it uses the headline 20%. The real deduction phases out above certain income levels and depends on your trade and your W-2 wages, none of which is modelled.

Additional Medicare Tax

The extra 0.9% that applies above higher income thresholds is not included in the self-employment figure.

Alternative Minimum Tax

AMT is not calculated at all.

Anything about your household

Dependents, a spouse's income, retirement contributions beyond the fields a given calculator offers, prior-year carryforwards, or withholding already paid.

Where each figure comes from

• Revenue Procedure 2025-32 — brackets and standard deduction, all filing statuses
• IRS Topic 751 — self-employment rates and the Social Security wage base
• Standard mileage rates — both 2026 periods
• Form 1040-ES — quarterly payment due dates

How these figures stay right

Every rate above lives in a single file, so no two calculators on this site can disagree with each other. A test suite checks each figure against the value published in its source document and fails the build if one changes unexpectedly — including specific checks that self-employment tax respects the wage base at high incomes, that brackets stay marginal, and that no calculator returns a negative or nonsensical result.

The figures are reviewed each autumn when the IRS publishes its annual inflation adjustments.