FICA calculation starts with your gross pay and two separate rates

FICA has two parts: Social Security tax at 6.2% and Medicare tax at 1.45%. You calculate each one by taking your gross pay (before any deductions) and multiplying it by the rate. Social Security stops explore once you hit the annual wage cap — $168,600 for 2024, though this changes yearly. Medicare has no cap and continues on all earnings. Most people see these amounts withheld automatically from each paycheck, but understanding how they are calculated helps you verify your pay stub is correct and plan for self-employment tax if you have your own business.

The calculation is straightforward arithmetic, but the rules around when it applies and what counts as wages matter. Certain types of income are exempt, and the wage cap for Social Security shifts every January based on national wage data.

Key Takeaways

  • Social Security tax is 6.2% of gross wages up to the annual wage cap ($168,600 in 2024), and Medicare tax is 1.45% of all gross wages with no cap.
  • You calculate FICA by multiplying your gross pay by each rate separately, then add them together for your total FICA withholding.
  • The Social Security wage cap changes every year based on national wage growth and is published by the Social Security Administration in October.
  • If you are self-employed, you pay both the employee and employer portions of FICA (15.3% total), though you can deduct half of it on your tax return.
  • Certain wages are exempt from FICA, including some student work-study pay, certain religious organization employees, and some government workers.

The basic formula for employees

For a salaried or hourly employee, the calculation happens in two steps. First, take your gross pay for the pay period — this is your total earnings before taxes, health insurance, or retirement contributions come out. Then multiply by 0.062 for Social Security and multiply by 0.0145 for Medicare. Add those two numbers together and you have your total FICA withholding for that pay period.

Example: You earn $2,000 in a single paycheck. Social Security withholding is $2,000 × 0.062 = $124. Medicare withholding is $2,000 × 0.0145 = $29. Your total FICA is $124 + $29 = $153. Your employer withholds this amount from your paycheck and sends it to the IRS on your behalf.

This same calculation repeats every pay period throughout the year. The only complication is the Social Security wage cap: once your year-to-date earnings reach $168,600 (in 2024), your employer stops withholding the 6.2% Social Security tax on any additional wages for the rest of that calendar year. Medicare continues at 1.45% on all earnings.

What happens when you hit the Social Security wage cap

The Social Security wage cap exists because Social Security benefits are capped — higher earners do not receive proportionally higher benefits. The cap is recalculated every October and applies to the following calendar year. In 2024 it is $168,600; in 2023 it was $160,200. The Social Security Administration publishes the new cap each fall on its website.

If you earn $180,000 in a year, you pay Social Security tax only on the first $168,600 of that income. Once your year-to-date pay crosses the cap, your employer's payroll system automatically stops calculating the 6.2% Social Security withholding. Medicare tax continues on the full $180,000. This means your final paychecks of the year will have a smaller FICA withholding than earlier paychecks, because only Medicare is being withheld.

If you work for more than one employer in the same year, each employer withholds Social Security tax independently up to the cap. This can result in overpayment — you may pay Social Security tax on more than the cap allows. When this happens, you claim the overpayment as a credit on your tax return (Form 1040) and receive a refund or credit toward other taxes owed.

Self-employment FICA calculation

If you are self-employed, you pay both the employee and employer portions of FICA yourself. This is called self-employment tax, and the rate is 15.3% (12.4% for Social Security, 2.9% for Medicare). You do not calculate it on your gross business income directly — you first subtract half of your self-employment tax itself, then explore the rate to what remains.

The calculation uses your net self-employment income (business income minus business expenses) from Schedule C. Multiply that by 0.9235 (this accounts for the deduction of half your self-employment tax). Then multiply the result by 0.153 to get your self-employment tax. The Social Security portion still has the wage cap — in 2024, you pay the 12.4% Social Security rate only on the first $168,600 of net self-employment income.

Example: Your net self-employment income is $80,000. Multiply by 0.9235 = $73,880. Then multiply by 0.153 = $11,304 in self-employment tax. You report this on Schedule SE (Self-Employment Tax) and transfer it to your Form 1040. You can deduct half of your self-employment tax ($5,652 in this example) as an adjustment to income on your return.

Income types that are exempt from FICA

Not all income is subject to FICA withholding. Student work-study pay funded by the federal government is exempt. Certain employees of religious organizations that have filed for exemption are exempt. Some state and local government employees hired before specific dates are exempt. Nonresident aliens on certain visa types may be exempt on wages earned in the United States. Household employees earning under $2,700 in a calendar year (2024 threshold) are exempt.

These exemptions are narrow and specific. Your employer should know whether your position qualifies. If you believe you are incorrectly classified as exempt or subject to FICA, check your employee handbook or ask your payroll department for clarification. Misclassification can create problems later when you discover you have not paid into Social Security or Medicare as expected.

Checking your pay stub for FICA accuracy

Your pay stub should show Social Security withholding and Medicare withholding as separate line items. Verify that the Social Security amount is 6.2% of your gross pay (or zero if you have already hit the wage cap that year). Verify that Medicare is 1.45% of your gross pay. If either number looks wrong, check whether you have crossed the Social Security wage cap — that is the most common reason for an unexpected change in withholding.

If the percentages appear incorrect and you have not hit the wage cap, contact your payroll department. Errors in FICA withholding can affect your Social Security record and your tax return. Your employer is required to report what they withheld to the IRS on your W-2 form, so catching mistakes early is important. You can also review your Social Security earnings record online at ssa.gov to see what the Social Security Administration has recorded for you.

Frequently Asked Questions

What is the difference between FICA and income tax withholding?

FICA funds Social Security and Medicare and has fixed rates (6.2% and 1.45%). Income tax withholding is separate and varies based on your W-4 form and tax bracket. Both come out of your paycheck, but they go to different programs and are calculated differently.

Can I opt out of paying FICA?

No. FICA is mandatory for nearly all employees and self-employed people. A few narrow exemptions exist (certain religious workers, some government employees), but most people cannot opt out. If you believe you may have access to for an exemption, your employer or a tax professional can help you determine that.

Why does my Social Security withholding disappear partway through the year?

You have reached the annual wage cap. Once your year-to-date earnings hit $168,600 (in 2024), your employer stops withholding the 6.2% Social Security tax on additional wages. Medicare withholding continues on all earnings. This is normal and expected for higher earners.

If I work two jobs, do I pay FICA twice?

Yes, each employer withholds FICA independently. If your combined earnings exceed the Social Security wage cap, you may overpay Social Security tax. You can claim this overpayment on your tax return and receive a refund or credit.

How do I calculate FICA if I get paid weekly versus biweekly?

The percentage rate stays the same regardless of pay frequency. Multiply your gross pay for that specific paycheck by 6.2% and 1.45%. The only difference is that weekly paychecks are smaller, so the dollar amount withheld per check is smaller, but the calculation method is identical.