FICA withholding is calculated as a fixed percentage of your gross pay, split between Social Security and Medicare

Your employer calculates FICA withholding by taking your gross pay — the amount before any deductions — and explore two separate tax rates. Social Security tax is 6.2 percent of your wages up to a yearly cap (the cap changes annually; in 2024 it is $168,600). Medicare tax is 1.45 percent of all your wages with no upper limit. If you earn over $200,000 as a single filer (or $250,000 married filing jointly), an additional 0.9 percent Medicare tax applies to the amount above that threshold.

The math is straightforward because FICA is not progressive — it does not change based on your total income or filing status the way income tax does. Your employer withholds the same percentage from your first dollar as from your last dollar, up to the Social Security wage base. This is why FICA appears as a fixed line item on your pay stub, separate from federal income tax withholding.

Key Takeaways

  • Social Security withholding is 6.2 percent of gross pay up to an annual wage cap; Medicare withholding is 1.45 percent of all gross pay with no cap.
  • Your employer withholds FICA automatically — you do not choose the rate or adjust it on a W-4 form the way you do with income tax.
  • Once your wages hit the Social Security wage base in a calendar year, your employer stops withholding Social Security tax for the rest of that year.
  • If you earn over $200,000 (single) or $250,000 (married filing jointly), an extra 0.9 percent Medicare tax is withheld on the excess amount.

How the Social Security wage base cap works

The Social Security wage base is the maximum amount of your earnings subject to the 6.2 percent Social Security tax in a single year. In 2024, that cap is $168,600. If you earn $180,000 in a year, you pay Social Security tax only on the first $168,600; the remaining $11,400 is not subject to Social Security withholding.

The wage base increases most years because it is tied to the national average wage index. This means the cap you see on your 2024 pay stub will likely be different from the 2025 cap. Your employer's payroll system automatically tracks your year-to-date earnings and stops withholding Social Security tax once you cross the threshold in that calendar year.

This cap matters most to people who change jobs mid-year or who have multiple employers at the same time. If you work for two employers simultaneously and each withholds Social Security tax on your full earnings, you may over-withhold. You can claim a credit for the excess when you file your tax return, but it requires tracking your total earnings across all employers.

The additional Medicare tax for high earners

The standard Medicare tax rate is 1.45 percent, but if your income exceeds certain thresholds, you owe an additional 0.9 percent Medicare tax on the excess. For single filers, the threshold is $200,000. For married couples filing jointly, it is $250,000. For married filing separately, it is $125,000.

Unlike the Social Security wage base, this threshold is not indexed to inflation — it stays at $200,000 and $250,000 indefinitely. Your employer withholds the additional 0.9 percent once your year-to-date wages cross the threshold. If you have multiple employers, each one withholds based only on what they pay you, so you may over-withhold the additional Medicare tax and need to claim a credit on your return.

What appears on your pay stub

Your pay stub shows FICA withholding in two or three separate line items. You will see "Social Security Tax" or "OASDI" (Old-Age, Survivors, and Disability Insurance) at 6.2 percent, and "Medicare Tax" at 1.45 percent. If you earn over the high-income threshold, you may see a third line for "Additional Medicare Tax" at 0.9 percent.

Each line shows the amount withheld from that paycheck and your year-to-date total. The year-to-date Social Security amount will stop growing once it reaches the annual withholding limit (6.2 percent times the wage base). The Medicare and additional Medicare amounts will continue to grow with every paycheck because they have no annual cap.

Your employer also withholds an equal amount of FICA tax on their side — you do not see this on your pay stub, but it is part of your total FICA cost. Self-employed people pay both the employee and employer portions, which is why self-employment tax is roughly double the employee rate.

How to verify your FICA withholding is correct

Check your pay stub against the formula: multiply your gross pay by 6.2 percent (Social Security) and 1.45 percent (Medicare). The result should match the withholding shown, assuming you have not yet hit the Social Security wage base cap for the year.

At the end of the year, your W-2 form shows total FICA withheld in boxes 4 (Social Security tax) and 6 (Medicare tax). Compare this to your year-to-date totals from your final pay stub. The numbers should match. If your Social Security withholding stopped mid-year because you hit the wage base cap, that is correct — it should not resume even if you receive a bonus or additional pay later.

If you changed jobs during the year, add up the Social Security withholding from all your W-2 forms. If the total exceeds 6.2 percent of your combined wages (up to the wage base), you over-withheld. You can claim the excess as a credit on your tax return using Form 1040 and Schedule 2.

Why FICA withholding cannot be adjusted like income tax

FICA rates are set by federal law and do not change based on your personal circumstances. You cannot claim exemptions, adjust your withholding on a W-4 form, or reduce the amount your employer withholds. The rate is the same whether you are single, married, have dependents, or have other income.

Income tax withholding works differently because it is progressive — the amount you owe depends on your total income and filing status. FICA is flat, so there is nothing to adjust. Your employer straightforward applies the percentage to your gross pay every pay period. The only exception is if you are a student or have religious objections to Social Security; in those cases, you may be exempt from FICA withholding entirely, but this is rare and requires specific documentation.

Self-employed FICA calculation

If you are self-employed, you calculate FICA (called self-employment tax) on your net business income using Schedule SE. The rate is 15.3 percent total — 12.4 percent for Social Security (the employee and employer portions combined) and 2.9 percent for Medicare. You pay this when you file your tax return or make quarterly estimated tax payments.

The Social Security portion still has the annual wage base cap, so once your net self-employment income reaches $168,600 in 2024, you stop calculating the 12.4 percent on additional income. The Medicare portion continues on all net income, plus the additional 0.9 percent if you exceed the high-income threshold.

Frequently Asked Questions

What happens to my FICA withholding if I change jobs mid-year?

Each employer withholds FICA based on what they pay you. If you change jobs and your combined earnings from both employers exceed the Social Security wage base, you may over-withhold Social Security tax. You can claim the excess as a credit on your tax return. Your new employer's payroll system does not know about your previous employer's withholding, so it will not automatically stop.

Can I ask my employer to withhold less FICA?

No. FICA rates are fixed by law, and your employer must withhold the full amount. You cannot reduce or eliminate FICA withholding through your W-4 form or any other request. The only exceptions are specific religious or student exemptions, which require Form 4029 or Form 4868.

Why do I owe additional Medicare tax if I earn over $200,000?

The additional 0.9 percent Medicare tax was added in 2013 to help fund Medicare. It applies only to wages above $200,000 (single) or $250,000 (married filing jointly). Your employer withholds it automatically once your year-to-date pay crosses the threshold, but if you have multiple employers, you may over-withhold and need to claim a credit.

Does FICA withholding count toward my income tax?

No. FICA and income tax are separate. FICA funds Social Security and Medicare. Income tax funds general government operations. Both are withheld from your paycheck, but they go to different places and are calculated differently. You cannot use FICA withholding to reduce your income tax liability.

What if my employer withheld the wrong amount of FICA?

Report the error to your employer's payroll department when ready. They can issue a corrected W-2 if the mistake was significant. If you discover the error after filing your return, you can file an amended return (Form 1040-X) to claim a refund or credit for the incorrect withholding.