The FIT line on your paycheck is federal income tax, the amount your employer withheld from that check and sent to the IRS as a down payment on your yearly income tax bill. It’s not a separate tax; it’s a prepayment of the one tax you reconcile every April when you file your return. How much comes out depends on what you earn, your filing status, and the choices you made on your W-4.
FIT Is Not the Same as FICA
Most pay stubs show at least two federal deductions, and mixing them up is the most common payroll misunderstanding. FIT funds the general federal budget. FICA is a separate set of deductions that funds Social Security and Medicare specifically.
FICA runs on fixed rates. The Social Security portion is 6.2% of your wages up to $184,500 in 2026, and the Medicare portion is 1.45% on all wages with no cap.1Internal Revenue Service. Social Security and Medicare Withholding Rates That combined 7.65% is predictable from one check to the next. An additional 0.9% Medicare tax kicks in on wages above $200,000 for single filers or $250,000 for joint filers.2Internal Revenue Service. Topic No. 560, Additional Medicare Tax Your employer matches your FICA dollar for dollar.
FIT works differently. It isn’t a flat percentage, and there’s no employer match. The amount depends on your tax bracket, the dependents you claimed, and whether you asked for extra withholding or claimed exemption. Two coworkers earning the same salary can have very different FIT amounts on their stubs because their W-4s look different.
How Your Employer Decides How Much FIT to Withhold
Your employer doesn’t guess. The calculation flows directly from Form W-4, officially called the Employee’s Withholding Certificate, which you fill out when you start a job.3Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate The form feeds a few inputs into IRS withholding tables that payroll then follows.
The most important input is filing status: single, married filing jointly, or head of household. This determines which set of tax rates and standard deduction amounts your employer applies.4Internal Revenue Service. Form W-4, Employee’s Withholding Certificate Picking the wrong status is one of the fastest ways to end up with too much or too little withheld all year.
Dependents matter next. For 2026, each qualifying child under 17 reduces your withholding by up to $2,200 through the child tax credit, and other dependents reduce it by $500 each.4Internal Revenue Service. Form W-4, Employee’s Withholding Certificate If you hold more than one job or your spouse works, Step 2 of the W-4 adjusts the math so you don’t come up short in April. Line 4(c) lets you add a flat dollar amount of extra withholding to each paycheck, useful if you have side income nobody’s withholding on.
Submit an updated W-4 whenever your life changes. Marriage, divorce, a new child, a second job: any of these can shift your tax picture enough that last year’s W-4 no longer fits. The IRS doesn’t tell your payroll department, and neither will your employer notice on its own.
Claiming Exempt
You can stop FIT withholding entirely in narrow circumstances. To qualify, you must have had zero federal income tax liability last year and expect zero liability this year. If both are true, write “Exempt” on your W-4 and your employer will withhold nothing for federal income tax.3Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate This mostly fits students and very low-income workers. The exemption expires every February 15, so you have to refile each year to keep it.
Why Two People With the Same Salary Pay Different FIT
Federal income tax uses a progressive structure. Different slices of your income are taxed at different rates, and only the dollars inside each bracket get taxed at that bracket’s rate.5Internal Revenue Service. Federal Income Tax Rates and Brackets A raise never leaves you worse off than before the raise, because only the new dollars hit the higher rate.
For a single filer with $60,000 of taxable income in 2026, the first $12,400 is taxed at 10%, the portion from $12,401 to $50,400 at 12%, and only the last $9,600 at 22%. The effective rate on the whole $60,000 lands well below 22%.
The 2026 brackets for single filers:6Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- 10% up to $12,400
- 12% from $12,401 to $50,400
- 22% from $50,401 to $105,700
- 24% from $105,701 to $201,775
- 32% from $201,776 to $256,225
- 35% from $256,226 to $640,600
- 37% above $640,600
Married couples filing jointly get wider brackets, which means more income is taxed at lower rates before hitting the next tier:6Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- 10% up to $24,800
- 12% from $24,801 to $100,800
- 22% from $100,801 to $211,400
- 24% from $211,401 to $403,550
- 32% from $403,551 to $512,450
- 35% from $512,451 to $768,700
- 37% above $768,700
Head of household and married filing separately filers have their own thresholds, and the IRS adjusts every bracket annually for inflation.7Office of the Law Revision Counsel. 26 USC 1 – Tax Imposed
Before any bracket math applies, you subtract the standard deduction. For 2026, the amounts are $16,100 for single or married filing separately, $32,200 for married filing jointly or qualifying surviving spouse, and $24,150 for head of household.6Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Taxpayers 65 and older may qualify for an enhanced deduction of up to $6,000 per person on top of the standard deduction, phasing out above $75,000 of modified adjusted gross income ($150,000 for joint filers).8Internal Revenue Service. Check Your Eligibility for the New Enhanced Deduction for Seniors Everything below the deduction effectively comes out tax-free, which is why someone with lower pay may see very little FIT withheld even without claiming exempt.
Why FIT Comes Out Every Pay Period
Federal tax is a pay-as-you-go system. You owe it as you earn it, not at the end of the year.9Internal Revenue Service. Pay As You Go, So You Won’t Owe For employees, that happens automatically through payroll withholding. Federal law requires every employer paying wages to deduct and withhold income tax based on IRS tables.10Office of the Law Revision Counsel. 26 USC 3402 – Income Tax Collected at Source The FIT line on your stub is that legal obligation in action.
What Happens at Tax Time
Your annual tax return is where all of this gets reconciled. The IRS compares your actual tax liability for the year against the total you’ve already paid in through FIT withholding (and any estimated payments). Overpaid, and the difference comes back as a refund. Underpaid, and you owe the balance.
This is why W-4 choices matter so much. Generous withholding means a bigger refund in April but smaller paychecks all year. Lean withholding keeps your paychecks larger and raises the odds of a bill in April. Neither approach changes your total tax; it only changes when the money leaves your hands.
For tax year 2025, the filing deadline is April 15, 2026.11Internal Revenue Service. IRS Announces First Day of 2026 Filing Season Form 4868 grants an automatic six-month extension to October 15 if you need more time to prepare the return.12Internal Revenue Service. Application for Automatic Extension of Time to File U.S. Individual Income Tax Return The extension gives you more time to file the paperwork, not more time to pay. Any tax you owe is still due April 15, and interest accrues on unpaid amounts from that date even with an extension on file.
One more point worth knowing: if your income falls below the filing threshold but your employer still withheld FIT, filing a return is the only way to get that money back as a refund.
When There’s No FIT Withholding
FIT only appears on paychecks from an employer. If you work for yourself, freelance, or earn significant income from investments or rental property, nobody is withholding federal income tax for you. You pay it through quarterly estimated tax payments instead. You generally need to make estimated payments if you expect to owe at least $1,000 after accounting for any withholding and refundable credits.13Internal Revenue Service. Form 1040-ES, Estimated Tax for Individuals (2026) The 2026 deadlines are April 15, June 15, September 15, and January 15 of the following year, with weekend and holiday due dates shifting to the next business day.14Internal Revenue Service. When Are Quarterly Estimated Tax Payments Due?
Self-employed workers also owe self-employment tax on top of federal income tax, the self-employed version of FICA at a combined 15.3% because there’s no employer paying the other half.15Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) If you hold a W-2 job and freelance on the side, the FIT withheld from your paycheck covers only the wage portion. The side income is still your responsibility to pay in through estimates or by increasing withholding on the W-4 at your main job.