What is FICA on your paycheck, and what does it pay for?

Look at almost any pay stub and you'll find a line labeled FICA, usually broken into two pieces. It's not a mistake, and it's not the same thing as your federal income tax withholding. It's a separate, mandatory payroll tax that funds Social Security and Medicare — and understanding it explains a lot about why your take-home pay looks the way it does.

What FICA actually stands for and what it pays for

FICA is short for the Federal Insurance Contributions Act, the law that created this payroll tax. It funds two specific federal programs, and per the IRS, it's withheld from wages alongside — but separately from — federal income tax:

• Social Security (OASDI): retirement benefits, disability benefits, and survivor benefits for eligible workers and their families.
• Medicare: hospital insurance and related health coverage, primarily for people age 65 and older and some younger people with qualifying disabilities.

Your pay stub might show "FICA" as one combined line, or it might split it into "Social Security" and "Medicare" (sometimes labeled OASDI and HI). Either way, it's the same underlying tax.

FICA vs. federal income tax: two completely different systems

These two deductions often sit right next to each other on a pay stub, which is exactly why people confuse them. They work nothing alike:

	Federal income tax	FICA
What it funds	General federal spending	Social Security & Medicare specifically
How it's calculated	Graduated brackets based on taxable income, filing status, deductions	Flat percentage of wages, from dollar one
Can it be zero?	Yes, for many low or moderate earners after deductions and credits	No — it applies to essentially all wage income
Governed by	Form W-4 elections and IRS withholding rules (IRS)	Set statutory rates, not adjustable by the worker

The IRS explains that federal income tax uses a graduated bracket structure, where a higher bracket applies only to the income above its threshold — and after subtracting deductions, some workers end up owing very little or nothing. FICA doesn't work that way at all; it's a flat rate applied to gross wages, with no equivalent to a standard deduction.

The employee and employer halves

FICA is designed as a shared cost. The IRS describes the structure this way, with the current-year rates published in IRS Publication 15:

• Employees have a share withheld directly from each paycheck — 6.2% of wages for Social Security and 1.45% for Medicare.
• Employers pay a matching share on the employee's behalf — the same 6.2% and 1.45% — which doesn't show up on the pay stub as a deduction because it isn't taken from the worker's wages.

That's 7.65% from you and another 7.65% from your employer — 15.3% of wages in total, roughly double what the stub shows. The rates are written into law and aren't indexed, so they rarely change; what moves every year is the Social Security wage base (below).

Self-employed workers pay both halves

If you're self-employed, there's no separate employer to split the cost with — you're both. This is generally handled through self-employment tax. The IRS describes it as combining both the employee and employer shares of Social Security and Medicare into one tax, paid directly by the self-employed person — typically through estimated tax payments rather than payroll withholding. Per IRS Topic 554:

• The rate is 15.3% (12.4% Social Security + 2.9% Medicare), once net self-employment earnings reach $400 for the year.
• It applies to 92.35% of net earnings, not 100% — a built-in adjustment that mirrors the fact that an employer's half isn't counted as an employee's wages.
• Half of it is deductible when calculating adjusted gross income, which softens (but doesn't erase) the double hit.

The Social Security cap — and why Medicare doesn't have one

Social Security tax only applies up to the wage base — a dollar limit on earnings subject to that portion of FICA. The Social Security Administration resets this limit every year, so:

• Earnings up to the wage base are taxed for Social Security at the standard rate.
• Earnings above the wage base in that same calendar year stop being taxed for Social Security — the withholding simply stops once you cross it.
• The 2026 wage base is $184,500, up from $176,100 in 2025 (SSA 2026 COLA fact sheet). That caps the employee's Social Security tax at $11,439 for the year (6.2% × $184,500). It resets every January.
• Two jobs can mean overpaying. Each employer withholds as if it's your only one, so combined Social Security withholding can blow past $11,439. The excess isn't lost — it's claimed as a credit on your federal return. (If a single employer over-withheld, that employer has to fix it, not the IRS.)

Medicare has no such cap. Every dollar of wage income, no matter how high, continues to be taxed for Medicare at the standard rate.

The Additional Medicare Tax

On top of the standard Medicare rate, an Additional Medicare Tax of 0.9% applies to wages above a threshold set by filing status (IRS Topic 560). There's no employer match on this piece, and unlike the wage base, the thresholds aren't indexed to inflation:

Filing status	Additional Medicare Tax starts above
Married filing jointly	$250,000
Married filing separately	$125,000
Single, head of household, others	$200,000

Why FICA shows up even when income tax doesn't

This is the part that trips up a lot of workers, especially students, part-timers, and low-income earners:

• Federal income tax has a floor. After standard deductions and credits, many lower earners owe little or no federal income tax for the year.
• FICA has no floor. It applies as a flat percentage of wages starting with the very first dollar, with no equivalent deduction or exemption.

FICA isn't a mistake on a low earner's pay stub, and it isn't optional. It's simply a different tax with a different purpose than the income tax that's often the focus of tax-season conversations.

Who pays less (or no) FICA

FICA covers almost all wages, but there are real exceptions an expert would check first:

• Cafeteria-plan benefits. Health, dental, and vision premiums, HSA contributions, and FSA contributions run through an employer's Section 125 plan generally skip FICA as well as income tax (IRS Publication 15-B). Traditional 401(k) deferrals do not — they still count as FICA wages.
• Students working for their own school while enrolled and attending classes are generally exempt.
• Many nonresident students and scholars on F-1 or J-1 visas (common visa categories for international students and researchers) are exempt for a limited period.
• Some state and local government workers covered by a public pension plan instead of Social Security don't pay the Social Security portion (they usually still pay Medicare).
• Members of certain religious groups that oppose insurance (mainly self-employed members) can apply for an exemption, which also gives up the benefits.

What the money actually buys

Paying FICA builds eligibility for specific programs. What any one person receives depends on their full earnings history and the rules when they claim:

• Social Security retirement benefits — eligibility generally takes 40 work credits. In 2026 you earn one credit for each $1,890 of covered earnings, up to four a year (SSA 2026 COLA fact sheet).
• Social Security disability benefits — potential eligibility if a qualifying disability prevents work, based on sufficient work history.
• Survivor benefits — potential eligibility for a worker's spouse or dependents in the event of the worker's death.
• Medicare coverage — hospital insurance (Part A) generally starting at 65 or after qualifying disability; about 10 years of Medicare-taxed work usually makes Part A premium-free.

A worked example

Two illustrative single filers using 2026 rules, with no pre-tax benefits:

	Earns $50,000	Earns $250,000
Social Security (6.2%, capped at $184,500)	$3,100	$11,439
Medicare (1.45%, no cap)	$725	$3,625
Additional Medicare (0.9% over $200,000)	$0	$450
Employee FICA for the year	$3,825	$15,514
FICA as a share of wages	7.65%	≈6.2%

The employer pays another $3,825 and $15,064 respectively (it doesn't match the 0.9%).

The non-obvious takeaway: because of the wage base, FICA takes a smaller share of pay from the $250,000 earner than from the $50,000 earner — the opposite of how income tax works. And at $50,000, FICA can easily be a bigger line than federal income tax.

If untangling what's actually being deducted from your paycheck — FICA, income tax withholding, and everything else — feels like more math than you want to do by hand, a tool built to break down a paycheck line by line can make it easier to see where the money on your pay stub is really going.