What is FIT on a pay stub? Federal income tax and FIT taxable wages

FIT on a pay stub stands for federal income tax. The FIT line is the amount withheld from this paycheck toward your federal income tax for the year. Some payroll systems label it FWT (federal withholding tax), Fed Tax or simply Federal.

FIT taxable wages (or Fed taxable gross) is the wage figure that the FIT amount was calculated on. It is not the same as gross pay.

How FIT taxable wages are worked out

Start with gross pay for the period and subtract the deductions that federal tax law treats as pre-tax:

• Traditional 401(k), 403(b), 457(b) and similar retirement deferrals
• Health, dental and vision premiums paid through a Section 125 plan
• Health savings account and flexible spending account contributions
• Some commuter and dependent care benefits

What is left is FIT taxable wages. A 2,500.00 gross paycheck with a 150.00 401(k) deferral and a 95.00 health premium has FIT taxable wages of 2,255.00.

Note that retirement deferrals reduce FIT taxable wages but not Social Security and Medicare wages. Section 125 items reduce both. That is why a stub can show three different wage bases.

How the FIT amount is calculated

Employers use the tables in IRS Publication 15-T. For a Form W-4 from 2020 or later, the automated method works like this:

1. Annualize the period's FIT taxable wages (multiply by the number of pay periods in the year).
2. Adjust for the W-4: add Step 4(a) other income, subtract Step 4(b) deductions, and add a standard amount unless the Step 2 box is checked.
3. Look up the annual tax in the table for the filing status (single, married filing jointly, or head of household), using the higher Step 2 table if that box is checked.
4. Subtract Step 3 credits (dependents).
5. Divide by the number of pay periods and add any Step 4(c) extra withholding.

Our pay stub generator performs exactly these steps for the 2026 tax year and shows the result on the FIT line. The methodology page lists the source tables.

FIT vs the other federal lines

FIT is an estimate of the year's tax spread across paychecks. Social Security and Medicare are the final tax; there is no annual return that adjusts them for most employees.

When FIT looks too high or too low

FIT changes with wages, so a paycheck with overtime or a bonus withholds more. It also changes when you file a new W-4. If the year-to-date FIT figure looks far from what you expect to owe, the IRS Tax Withholding Estimator can suggest W-4 changes. Two-income households often under-withhold unless the Step 2 box is checked on both W-4s.

See FIT calculated on a pay stub