What is a Federal Income Tax?
Federal income tax is what you owe the IRS on your taxable income — your total income minus adjustments (like 401(k) and HSA contributions) and either the standard deduction or your itemized deductions. The U.S. uses a progressive system: income is taxed in layers, each at its own rate, from 10% up to 37%.
Your 'tax bracket' is just the rate on your highest layer. Credits like the Child Tax Credit then reduce the tax itself, dollar for dollar, after the brackets have done their work.
Why it matters
Understanding the layered system changes decisions. People turn down raises or overtime fearing a higher bracket will 'cost' them — but only the new income is taxed at the higher rate, never the income beneath it. Your effective rate, the number that actually matters for budgeting, is always lower than your bracket.
It also shows where the levers are: pre-tax contributions lower your taxable income (and can drop you a bracket), the standard deduction shields a large first chunk tax-free, and credits reduce the final bill directly. Seeing the bracket-by-bracket breakdown makes all of this concrete instead of abstract.
What to do next
Enter your income, filing status, and deductions, and read the breakdown table to see how each slice of income is taxed. If you're near a bracket edge, a larger 401(k) or HSA contribution might lower both your taxable income and your rate.
This page covers income tax; for the rest of your picture, use the linked tools: the paycheck calculator for FICA and per-check take-home, the tax refund estimator to check your withholding, and the self-employment and capital-gains calculators if you have 1099 or investment income.
Frequently asked questions
What's the difference between the 2025 and 2026 tax year?
The 2025 tax year is what you file a return for in early 2026; the 2026 tax year is what you'll file in early 2027 and plan for during 2026. The brackets and standard deduction are slightly higher for 2026 due to inflation adjustments, so the same income can owe a bit less. Use the year toggle to switch.
Does a higher tax bracket mean all my income is taxed at that rate?
No — this is the most common tax misconception. Only the portion of your income above each threshold is taxed at the higher rate; the rest is taxed at the lower rates beneath it. That's why your effective rate (total tax ÷ total income) is always lower than your top bracket. The breakdown table on this page shows exactly how each slice is taxed.
What is the standard deduction for 2026?
For the 2026 tax year it's $16,100 for single filers and married filing separately, $24,150 for heads of household, and $32,200 for married couples filing jointly. You subtract it (or your itemized deductions, whichever is larger) before the brackets apply.
What's the difference between marginal and effective tax rate?
Your marginal rate is the rate on your last dollar of income — your tax bracket. Your effective rate is your total tax divided by your total income. The effective rate is always lower because of the layered, progressive system. This calculator shows both.
Where did self-employment tax, capital gains, and the refund estimate go?
To keep each tool focused, they now have dedicated pages: the self-employment tax calculator for 1099 income, the capital gains tax calculator for investment sales, and the tax refund estimator for comparing your withholding to what you owe. They're linked from this page.
Is this calculator my actual tax bill?
It's a close estimate of federal income tax using your income, filing status, deductions, and the Child Tax Credit. It doesn't include every credit, the FICA payroll tax, state income tax, or special situations, so treat it as a planning tool rather than a filed return.
2025 & 2026 federal brackets, standard deduction, and Child Tax Credit — IRS Rev. Proc. 2024-40 & 2025-32 (2026).