Why your paycheck stub will not match this calculator
If you paste a salary into the paycheck calculator and then open a real stub, the net will almost always differ. That is expected. This page lists the usual gaps so you can tell a modeling limit from a payroll error.
State and local tax
This site estimates federal income tax and FICA only. Many states withhold income tax on the same check. Cities and school districts sometimes add another line. A stub from New York, California, or a locality with an earnings tax will show a lower net than this page even when federal lines are close. To compare, look at federal income tax, Social Security, and Medicare on the stub — not the net — or subtract your state’s line from this site’s take-home by hand.
Pre-tax benefits
401(k), HSA, FSA, and employer health premiums often come out before federal income tax. Some also reduce FICA wages. This calculator uses the gross you type as if none of those existed. A $60,000 salary with 6% to a traditional 401(k) is not $60,000 of federal taxable wages. Entering the salary alone here will overstate federal tax and understate take-home relative to that stub. If you want a closer federal estimate, subtract known pre-tax amounts from the pay you enter. That is a rough workaround, not a benefits engine.
Publication 15-T versus this annual shortcut
Payroll uses IRS Publication 15-T. The percentage method looks at this period’s wages, pay frequency, W-4, and sometimes a mid-year remaining-periods adjustment. This site annualizes, taxes the year, and divides. Rounding, the multiple-jobs checkbox, and extra withholding (W-4 Step 4(c)) will move the federal line even when salary and status match. Close is good. Exact is not the design. Details: federal withholding and Form W-4.
Pay frequency, overtime, and bonuses
Weekly, biweekly, semimonthly, and monthly splits change the size of each check. Overtime in one period can be taxed as if you earn that rate all year, which withholds more federal tax on that check than a flat salary model. Bonuses are often withheld at a flat supplemental rate. This calculator has no overtime or bonus field. A holiday check that includes a bonus will not match a 1/26th of salary estimate.
Social Security wage base during the year
Once wages pass the 2026 Social Security wage base of $184,500 at an employer, later checks drop the 6.2% employee share. This site spreads the annual Social Security amount across all periods. High earners will see a different pattern month to month on a stub. Annual Social Security withheld should still be near 6.2% of wages up to the cap. See FICA vs income tax.
When a mismatch is worth asking payroll
- Federal income tax is zero all year on a mid five-figure salary with no dependents and no huge pre-tax deductions.
- Social Security is not 6.2% of FICA wages (before the wage base).
- Medicare is not 1.45% of Medicare wages (plus 0.9% only after the Additional Medicare threshold).
- A W-4 change you submitted weeks ago has not appeared, and payroll confirms they received it.
Otherwise, start from the stub’s federal and FICA lines, not from net pay, before assuming the employer is wrong. This site is an educational estimate, not a payroll audit.