FICA vs federal income tax withholding on your paycheck

Is FICA the same as federal income tax? No. FICA is Social Security (6.2%) and Medicare (1.45%), taken from wages at flat rates. Federal income tax withholding is figured from your W-4, filing status, and the tax brackets. Both come out of every W-2 paycheck, but they are different taxes on separate lines.

FICA is the employee share of Social Security and Medicare. It is a set percentage of wages, with a wage cap on Social Security. Federal income tax withholding is a separate calculation that uses filing status, the standard deduction, brackets, and W-4 credits. Mixing those two lines can make it look like "dependents did nothing" or "Social Security went down when I got married." Dependents and filing status change income tax. They do not change FICA rates.

This page is an educational explainer, not tax advice, a payroll system, or IRS software.

2026 employee rates used on this site

Social Security: 6.2% of wages up to $184,500 for 2026. After that wage base, the 6.2% employee share stops for the rest of the calendar year at that employer. If you work more than one job, combined wages can go past the cap; any excess withheld is sorted out when you file.
Medicare: 1.45% of all wages. There is no Medicare wage base.
Additional Medicare Tax: 0.9%. Employers must withhold it on wages they pay you above $200,000 in a calendar year, regardless of filing status. Whether you actually owe it depends on your filing status: the IRS threshold is $250,000 for married filing jointly, $125,000 for married filing separately, and $200,000 for single, head of household, and qualifying widow(er) with dependent child. There is no employer match on the extra 0.9%.

Your employer also pays a matching 6.2% Social Security (up to the same wage base) and 1.45% Medicare. That match is a cost of employment and does not appear as a deduction from your take-home pay.

Sources: SSA, Contribution and Benefit Base; IRS Topic No. 751; IRS Publication 15 (2026), What's New; IRS Questions and Answers for the Additional Medicare Tax (all checked Oct 7, 2026).

Is FICA part of federal withholding?

Both are federal amounts your employer withholds from each paycheck, so in that loose sense, yes. But they are different taxes:

FICA (Social Security and Medicare) funds those two programs. It is a flat percentage of wages. Your W-4, dependents, and filing status do not change it.
Federal income tax withholding is a prepayment of your annual income tax. Your W-4, filing status, and the brackets drive it.

On a pay stub you will usually see them on separate lines. Common labels include:

Social Security: "FICA," "OASDI," "SS," or "Soc Sec"
Medicare: "MED," "MEDI," or "Medicare"
Federal income tax: "FIT," "Fed W/H," or "Federal Income Tax"

Some payroll systems group all three under a heading like "Federal taxes," which is why it's easy to think FICA is part of income tax. Labels vary by employer and payroll provider. If your stub uses a combined line, ask payroll for the breakdown. See why your stub won't match this calculator.

Why the Social Security line can shrink late in the year

If you earn past $184,500 in 2026 at one job, later checks stop taking the 6.2%. Take-home jumps even though you didn't get a raise. Medicare usually continues. People sometimes read that jump as a tax-law change. It is the wage base. IRS Publication 15 tells employers to stop collecting the employee share of Social Security tax once wages for the year reach $184,500, and to keep collecting Medicare on all wages.

This site annualizes a single salary, so a $190,000 salary will show Social Security only on the first $184,500 for the year, spread across the pay periods you chose. A real payroll system stops the 6.2% on the check that crosses the cap, so the pattern across the year looks different even when the annual total is close.

FICA wages vs. gross wages

FICA wages are not always the same as gross wages, and they are not always the same as the wages used for income tax. Your Form W-2 shows the difference:

Box 1 — wages, tips, other compensation (the federal income tax figure)
Box 3 — Social Security wages (capped at the wage base)
Box 5 — Medicare wages and tips (generally Box 3 Social Security wages plus Box 7 Social Security tips, with no wage base limit). Federal, state, or local government employers whose employees pay only Medicare tax enter Medicare wages in Box 5.

Pre-tax benefits are the usual reason these boxes differ:

Traditional 401(k) deferrals: IRS Publication 15 lists elective 401(k) deferrals as generally exempt from federal income tax withholding but taxable for Social Security and Medicare. So a 401(k) lowers Box 1 but not Boxes 3 and 5.
Section 125 (cafeteria) plans: Publication 15 says benefits under a cafeteria plan may qualify for exclusion from Social Security and Medicare wages, and that HSA contributions made through a Section 125 salary-reduction arrangement aren't wages for employment taxes. Pre-tax health premiums through a cafeteria plan often lower all three boxes.

This calculator does not model 401(k), HSA, health premiums, or other pre-tax benefits. It applies FICA to the gross pay you enter. If your stub's Social Security wage is lower than gross, a pre-tax benefit is usually why.

Sources: IRS General Instructions for Forms W-2 and W-3 (2026) (checked Oct 8, 2026); IRS Publication 15 (checked Oct 7, 2026).

FICA vs. self-employment tax

Self-employed people don't have an employer to pay half, so they pay both halves themselves through self-employment (SE) tax on net earnings. The IRS lists the SE tax rate as 15.3%: 12.4% for Social Security and 2.9% for Medicare. SSA confirms the 2026 Social Security rate for self-employment income is 12.4%, applied up to the same $184,500 base. Additional Medicare Tax can also apply to self-employment income above the filing-status thresholds.

This calculator is built for W-2 wages only. It does not estimate SE tax on Schedule C or other self-employment income.

Sources: IRS, Self-Employment Tax (Social Security and Medicare Taxes); SSA, Contribution and Benefit Base (both checked Oct 7, 2026).

FICA vs. FICO

FICO is a brand of credit score, not a tax. FICA (Federal Insurance Contributions Act) is the payroll tax for Social Security and Medicare. They just look alike.

Why the calculator splits the lines

On the paycheck calculator, federal income tax, Social Security, and Medicare are shown separately so you can see which piece moved. Add children under 17: federal tax should fall; FICA should stay. Switch single to married jointly on the same salary: federal tax should fall because the standard deduction and brackets change; FICA should stay. If both move, something else is going on (a different gross, a different year, or a stub that already includes state tax in a combined "taxes" line).

FAQ

Is FICA the same as federal income tax?

No. FICA is Social Security and Medicare, charged at flat rates on wages. Federal income tax is figured from your income, filing status, deductions, and credits, and your employer withholds it based on your W-4.

Does FICA count as federal withholding?

It is federal and it is withheld from your paycheck, so some stubs group it under "federal taxes." But it is not federal income tax withholding. It shows up on its own lines (Social Security and Medicare) and in separate W-2 boxes (4 and 6, versus Box 2 for federal income tax withheld).

What's the difference between FICA and FIT?

FIT is federal income tax withholding. FICA is Social Security plus Medicare. FIT changes with your W-4, filing status, and dependents. FICA doesn't: it's 6.2% for Social Security up to the 2026 wage base of $184,500 and 1.45% for Medicare on all wages, plus 0.9% Additional Medicare withholding on wages over $200,000 at one employer.

Are FICA wages the same as gross wages?

Not always. Some pre-tax benefits, such as many Section 125 cafeteria-plan health premiums, reduce FICA wages. Traditional 401(k) deferrals reduce income tax wages but not FICA wages. Compare W-2 Boxes 1, 3, and 5 to see the difference. This calculator does not model pre-tax benefits.

Do dependents change FICA?

No. Dependents reduce estimated federal income tax through W-4 Step 3 credits. Social Security and Medicare rates stay the same.

Why did my Social Security deduction stop?

You probably passed the 2026 Social Security wage base of $184,500 at that employer. The 6.2% employee share stops for the rest of the calendar year; Medicare continues.

Is FICA the same as self-employment tax?

They fund the same programs. Employees split FICA with their employer; self-employed people pay both halves through SE tax (15.3% combined). This calculator covers W-2 wages only.

Sources (checked Oct 7, 2026)

SSA, Contribution and Benefit Base — 2026 base $184,500; 6.2% employee/employer; 12.4% self-employment; Medicare 1.45% each, no limit: https://www.ssa.gov/oact/cola/cbb.html
IRS, Topic No. 751, Social Security and Medicare Withholding Rates — 6.2%/1.45%; 0.9% withheld over $200,000; 2026 wage base $184,500 (IRS page updated Sep 24, 2026): https://www.irs.gov/taxtopics/tc751
IRS, Questions and Answers for the Additional Medicare Tax — 0.9%; thresholds $250,000 MFJ, $125,000 MFS, $200,000 others: https://www.irs.gov/businesses/small-businesses-self-employed/questions-and-answers-for-the-additional-medicare-tax
IRS, Publication 15 (Circular E), Employer's Tax Guide (2026) — What's New rates and wage base; 401(k) deferrals subject to FICA; cafeteria plans: https://www.irs.gov/publications/p15
IRS, General Instructions for Forms W-2 and W-3 (2026) — Boxes 1, 3, 5; Box 5 is Medicare wages and tips, the same as those subject to social security tax (boxes 3 and 7) except there is no wage base limit; page last reviewed or updated Apr 30, 2026 (checked Oct 8, 2026): https://www.irs.gov/instructions/iw2w3
IRS, Self-Employment Tax (Social Security and Medicare Taxes) — 15.3% = 12.4% + 2.9%: https://www.irs.gov/businesses/small-businesses-self-employed/self-employment-tax-social-security-and-medicare-taxes

This is an educational estimate, not a payroll system and not IRS software.