What FICA is
FICA — the Federal Insurance Contributions Act — bundles the two payroll taxes that fund Social Security and Medicare. Unlike federal income tax, FICA is not progressive and applies to the first dollar you earn: no standard deduction, no brackets, and no reduction for 401(k) deferrals. Your employer pays a matching amount that never appears on your stub; self-employed workers pay both halves as SECA tax.
Social Security: 6.2% with a ceiling
The employee share is 6.20% of gross wages, but only up to the wage base — $184,500 for 2026 (SSA cost-of-living announcement; it was $176,100 in 2025). Above that, Social Security withholding simply stops: the maximum you can pay in 2026 is $11,439.00. On a $75,000 salary the engine computes $4,650.00 withheld; on $220,000 the line is capped at $11,439.00 — same as someone earning exactly the wage base.
Medicare: 1.45% with no ceiling — plus 0.9% for high earners
Medicare has two parts. The standard 1.45% applies to all wages, unlimited — our $220,000 example pays $3,190.00. Then the Additional Medicare Tax adds 0.90% on wages above a statutory threshold set in 2013 and never indexed: $200,000 for single filers and heads of household, $250,000 married filing jointly. Employers must withhold it once your pay crosses the threshold in the calendar year, regardless of filing status. Here that is $180.00 on the $20,000 above the line.
| FICA line (2026) | $75,000 salary | $220,000 salary |
|---|---|---|
| Social Security (6.20%) | $4,650.00 | $11,439.00 (capped) |
| Medicare (1.45%) | $1,087.50 | $3,190.00 |
| Additional Medicare (0.90%) | $0.00 | $180.00 |
The half you never see
Your employer pays a matching 6.20% Social Security and 1.45% Medicare on top of your wages — 7.65% of payroll that never touches your stub because it was never part of your gross. Self-employed workers pay both halves themselves through SECA (Self-Employment Contributions Act) — a 15.3% rate on net earnings, with half deductible as an adjustment to income. Economically, most of the employer share is still borne by workers through lower wages — which is why the « true » FICA burden is closer to 15% than to the 7.65% your stub shows.
How the wage base moves
The Social Security wage base is indexed to national average wage growth and announced each fall by the SSA: $184,500 for 2026, up from $176,100 in 2025. Crossing the cap mid-year is visible on real pay stubs — Social Security withholding simply stops once cumulative wages reach the base, then resumes in January. The Medicare thresholds, by contrast, are written in the tax code and not indexed — the $200,000/$250,000 lines catch more taxpayers every year.
FICA on your W-2
At year end the W-2 splits this cleanly: Box 3 reports Social Security wages (capped at the wage base), Box 5 Medicare wages (uncapped), and Boxes 4/6 the tax actually withheld. A useful sanity check — Box 4 divided by Box 3 should be 6.20%, and Box 6 divided by Box 5 should be 1.45% unless you crossed the Additional Medicare threshold. Box 1, your taxable wages, is a different animal and will be lower if you defer pre-tax.
What FICA is not
Three common confusions. First, FICA is not your income tax — it is a separate, parallel withholding with its own rules (see the paycheck guide). Second, pre-tax 401(k) or HSA contributions do not lower FICA wages: you still pay Social Security and Medicare on the deferred amount. Third, the wage base only caps Social Security — Medicare and Additional Medicare never stop. Rates and the wage base come from IRS Publication 15 and the SSA Federal Register notice, verified for 2026 (see methodology). Compare states in the calculator. Indicative estimate computed with the official parameters in force — not a pay slip, and not tax or legal advice.