🎯 In 30 seconds: Federal income tax is charged in layers. Your top bracket only applies to the last dollars you earn, so a raise never shrinks your take-home pay. Deductions lower the income that gets taxed; credits lower the tax itself. Withholding is a prepayment, and a big refund means you lent the IRS money for free.
Brackets: tax is charged in layers
The IRS splits your taxable income into slices. Each slice is taxed at its own rate, and only the income inside that slice pays that rate. Taxable income is what is left after deductions, not your salary.
For 2026 (returns filed in 2027), the IRS published these thresholds:
| Rate | Single: taxable income | Married filing jointly |
|---|---|---|
| 10% | $0 to $12,400 | $0 to $24,800 |
| 12% | over $12,400 | over $24,800 |
| 22% | over $50,400 | over $100,800 |
| 24% | over $105,700 | over $211,400 |
| 32% | over $201,775 | over $403,550 |
| 35% | over $256,225 | over $512,450 |
| 37% | over $640,600 | over $768,700 |
The 2026 standard deduction is $16,100 for single filers, $32,200 for married couples filing jointly and $24,150 for heads of household.
Marginal versus effective rate, worked through
Take a single filer earning $70,000 in wages in 2026 with no other income who takes the standard deduction.
| Wages | $70,000 |
| Minus standard deduction | −$16,100 |
| Taxable income | $53,900 |
| 10% on the first $12,400 | $1,240 |
| 12% on $12,400 to $50,400 ($38,000) | $4,560 |
| 22% on the last $3,500 | $770 |
| Federal income tax | $6,570 |
Her marginal rate is 22%: the rate on her next dollar. Her effective rate is $6,570 ÷ $70,000, about 9.4% of her pay. A $1,000 raise adds $220 of federal income tax, not $1,000 times some bigger rate. This example leaves out state tax, Social Security and Medicare payroll taxes, and any credits.
Deductions versus credits
A deduction lowers taxable income, so it is worth your marginal rate. A credit comes off the tax bill dollar for dollar.
- A $1,000 deduction at a 22% marginal rate saves $220.
- A $1,000 credit saves $1,000.
- Some credits are refundable: if the credit is bigger than your tax, you get the difference back. The Earned Income Tax Credit is the largest example; for 2026 its maximum is $8,231 for a family with three or more qualifying children.
- You either take the standard deduction or itemize (mortgage interest, state and local taxes, charitable gifts and a few others). Itemize only when the total beats the standard deduction. Most households take the standard deduction.
The W-4 and withholding
Your employer withholds tax from each paycheck based on the Form W-4 you filled in. If the W-4 is off, you either owe at filing time or get a large refund.
- Revisit the W-4 when you start a job, marry, divorce, have a child, pick up a second job or start side income.
- Use the IRS Tax Withholding Estimator. It takes about 25 minutes and produces a filled-in W-4 you hand to payroll. The IRS suggests a check every January.
- If you have income with no withholding (freelance work, interest, investment gains), plan for it: more withholding at your job or quarterly estimated payments. Owing a lot at filing can bring an underpayment penalty.
Filing for free
- IRS Free File: brand-name guided software at no cost if your adjusted gross income is under the IRS limit ($95,000 or less on the IRS page at the time of writing). Free File Fillable Forms work at any income but give no guidance. The IRS page currently says Free File is closed until January 2027.
- VITA and TCE: free in-person preparation by IRS-certified volunteers. VITA generally serves people earning about $70,000 or less, people with disabilities and limited-English speakers; TCE focuses on taxpayers 60 and older.
- IRS Direct File was not offered in the 2026 filing season, and no return date had been announced as of this writing. Check irs.gov before you plan on it.
Keep a copy of every return and the documents behind it. For where tax-advantaged accounts fit, see the 12 moves.