How US federal income tax is actually calculated
Federal income tax in the United States is progressive, which means different slices of your income are taxed at different rates. The calculation runs in two stages. First, the standard deduction is subtracted from gross income to give taxable income. Second, that taxable income is sliced across the bracket thresholds, and each slice is taxed at its own rate. Nothing about earning more money causes your earlier income to be taxed at a higher rate.
This calculator uses IRS tax year 2026 federal figures from Rev. Proc. 2025-32. The standard deduction is 16,100 for single filers, 32,200 for married filing jointly, and 24,150 for head of household. The single-filer brackets for 2026 are 10 percent up to 12,400 of taxable income, 12 percent to 50,400, 22 percent to 105,700, 24 percent to 201,775, 32 percent to 256,225, 35 percent to 640,600, and 37 percent above that. Married filing jointly and head of household have their own thresholds, which is why changing filing status moves the result even when income stays the same.
On top of income tax, the calculator adds FICA payroll taxes: Social Security at 6.2 percent on wages up to the 2026 wage base of 184,500, Medicare at 1.45 percent on all wages with no cap, and Additional Medicare at 0.9 percent on wages above 200,000 for single and head of household filers or 250,000 for married filing jointly. These are the employee shares only. The matching employer contribution is not shown because it does not come out of your pay.
A worked example: 85,000 gross, single filer
Start with 85,000 of gross income and the single standard deduction of 16,100. Taxable income is 85,000 minus 16,100, or 68,900. Now slice that across the brackets. The first 12,400 is taxed at 10 percent, giving 1,240. The next slice runs from 12,400 to 50,400, a span of 38,000, taxed at 12 percent, giving 4,560. The remaining slice runs from 50,400 to 68,900, a span of 18,500, taxed at 22 percent, giving 4,070. Federal income tax is 1,240 plus 4,560 plus 4,070, or 9,870.
FICA is calculated on gross income rather than taxable income, so no deduction applies. Social Security is 85,000 times 6.2 percent, or 5,270, since 85,000 is below the 184,500 wage base. Medicare is 85,000 times 1.45 percent, or 1,232.50. Income is below 200,000, so Additional Medicare is zero. Total FICA is 6,502.50.
Total federal tax is 9,870 plus 6,502.50, or 16,372.50, leaving take-home pay of 68,627.50 before any state tax. The effective rate is 16,372.50 divided by 85,000, or about 19.3 percent. The marginal rate is 22 percent, because the last dollar earned fell in the 22 percent bracket. Those two numbers are different by design, and the gap between them is the single most useful thing the calculator shows.
What state tax adds and how the state tables work
Selecting a state adds a state income tax line to the result. States fall into three groups. Some have no income tax on wages at all, so selecting them adds nothing. Some apply a single flat rate to income. Others run their own progressive brackets, which can be structured quite differently from the federal ones, with their own deductions, exemptions, and thresholds that may or may not vary by filing status.
State tables in this tool are the most recent published values available, and some of them may still be for tax year 2025 rather than 2026, because states publish their inflation adjustments on their own schedules. The federal side is unambiguously tax year 2026. If the state figure matters for a decision, check it against your state revenue department before relying on it.
Local taxes are not included. Several cities and counties levy their own income tax on top of the state rate, and those are not part of any state table here. If you live somewhere with a municipal income tax, the total shown will be lower than what you actually pay.
What this calculator does not include
The calculation assumes you take the standard deduction. It does not itemize, so mortgage interest, state and local tax deductions, charitable giving, and medical expenses have no effect on the result. For most filers the standard deduction is larger than itemized deductions, which is why it is the default, but if you itemize a substantial amount your real tax will be lower than shown.
Tax credits are not applied. The Child Tax Credit, the Earned Income Tax Credit, education credits, and residential energy credits all reduce tax dollar for dollar after the bracket calculation, and none of them appear here. For households that qualify for meaningful credits, the gap between this estimate and the actual bill can be large.
Also absent: pre-tax retirement contributions such as a traditional 401(k), which reduce taxable income but not Social Security and Medicare wages; Health Savings Account contributions; self-employment income and the self-employment tax that comes with it; capital gains and qualified dividends, which have their own rate schedule; and the Net Investment Income Tax. The tool treats all input as ordinary wage income for a single tax year.
The mistake people make with marginal rates
The most common misunderstanding in US income tax is believing that crossing into a higher bracket raises the rate on all your income. It does not. If a raise pushes you from the 12 percent bracket into the 22 percent bracket, only the dollars above the threshold are taxed at 22 percent. Taking a raise or working overtime cannot leave you with less money after tax through bracket movement alone.
The second common error is comparing a marginal rate against someone else's effective rate. The marginal rate answers a forward-looking question: what happens to the next dollar. The effective rate answers a backward-looking one: what share of everything earned went to tax. In the worked example above, those are 22 percent and 19.3 percent for the same person in the same year.
There are real cliff effects in the tax and benefits system, but they come from credit phase-outs and income-tested benefits, not from the brackets themselves. Those phase-outs are outside the scope of this calculator, which models brackets and payroll tax only.