Taxes

Personal Tax Fundamentals: How Federal Income Tax Works

Reviewed by Unpack Money Research Desk · Updated October 29, 2026 · Our review process

Quick answer

Most US workers pay federal income tax through a pay-as-you-go system: employers withhold tax from paychecks, and self-employed people generally pay in quarterly installments. At filing time, you total your income, subtract deductions, apply the tax rates to what remains, then subtract credits. If you paid more than you owe, you get a refund; if you paid less, you owe the difference.

The five steps, in order

Educational information only. This page explains how the US federal income tax system works in general terms. It is not tax, legal, or financial advice, and it is not a recommendation for your situation. Tax law changes, and your return depends on your own facts — consult a qualified tax professional for advice about your return.

Step 1: Add up your income

Income includes wages, salaries, tips, business income, interest, dividends, capital gains, rental income, and retirement distributions, among other items. Your employer reports wages on Form W-2; banks report interest on Form 1099-INT (see Is Savings Account Interest Taxable? and Is CD Interest Taxable?).

Step 2: Subtract adjustments to get adjusted gross income (AGI)

Certain items — for example, part of self-employment tax, and deductible retirement contributions in qualifying cases — reduce AGI. AGI matters because many limits and phase-outs are keyed to it.

Step 3: Subtract a deduction to get taxable income

You take either the standard deduction or itemized deductions, whichever is larger for you. For tax year 2026, the IRS standard deduction is $16,100 for single filers and married individuals filing separately, $32,200 for married couples filing jointly, and $24,150 for heads of household (IR-2025-103, verified 2026-10-29).

Step 4: Apply the tax rates

Federal income tax uses graduated rates — 10%, 12%, 22%, 24%, 32%, 35%, and 37% for tax year 2026. Each rate applies only to the slice of taxable income inside its bracket, not to your whole income. See How Tax Brackets Work for a worked example.

Step 5: Subtract credits to get your final tax

Credits reduce tax dollar for dollar, unlike deductions, which reduce taxable income. Nonrefundable credits can reduce your tax to zero but not below it; refundable credits can produce a refund even with no tax liability.

Worked example (illustrative, tax year 2026)

A single filer with $60,000 of income and no adjustments takes the $16,100 standard deduction, leaving $43,900 of taxable income. Tax is then figured bracket by bracket on that $43,900 — not at one flat rate on the whole amount. Any credits are subtracted last, and the result is compared with tax already paid through withholding or estimated payments.

Withholding vs. estimated payments

Employees generally have tax withheld from each paycheck; the amount depends on the Form W-4 they filed. People with income that is not subject to withholding — freelancers, landlords, investors — generally must make quarterly estimated payments if they expect to owe at least $1,000 after withholding and refundable credits (IRS estimated-tax FAQ, verified 2026-10-28). See Quarterly Estimated Taxes.

Common mistakes

What this means for you

Federal tax is a sequence, not a single rate: income, minus adjustments, minus a deduction, taxed bracket by bracket, minus credits, compared with what you already paid. Follow the steps in order and the “surprise bill” usually turns out to be one missed step. Unpack Money currently earns $0 affiliate revenue and has no approved affiliate programs, and this page contains no affiliate links.

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