FICA tax comes out of your paycheck in two parts: Social Security and Medicare

FICA tax is calculated as a percentage of your gross wages — the amount you earn before any deductions. The calculation is straightforward: you multiply your gross pay by the tax rate for each component, then subtract the result from your paycheck. Social Security takes 6.2% of your wages up to a yearly cap, and Medicare takes 1.45% of all your wages with no cap. If you are self-employed, you pay both the employee and employer portions, which doubles the rate.

Your employer handles this calculation automatically if you are a W-2 employee. The withholding appears on your pay stub as separate line items. If you are self-employed or a contractor, you calculate and pay FICA yourself, usually quarterly. Understanding how these numbers work helps you predict your take-home pay and catch errors on your pay stub.

Key Takeaways

  • Social Security tax is 6.2% of wages up to an annual wage base that changes each year; Medicare tax is 1.45% of all wages with no limit.
  • Your employer withholds both taxes automatically from your paycheck if you are a W-2 employee, and you can see the amounts on your pay stub.
  • Self-employed workers pay both the employee and employer portions of FICA, totaling 15.3%, and must calculate and remit the tax themselves.
  • Additional Medicare tax of 0.9% applies to wages above $200,000 for single filers and $250,000 for married couples filing jointly.

How to calculate Social Security tax on your paycheck

Social Security tax applies only to wages below the annual wage base. For 2024, that cap is $168,600. This means once you earn $168,600 in a calendar year, no more Social Security tax comes out of your remaining paychecks that year.

To calculate Social Security tax, multiply your gross wages by 0.062 (which is 6.2%). If you earn $2,000 in a paycheck and have not yet hit the wage cap, the Social Security tax is $2,000 × 0.062 = $124. If you are paid biweekly and earn $2,000 per check, you will hit the wage cap sometime in the fall, and your final paychecks that year will have no Social Security tax withheld.

The wage base changes annually. The Social Security Administration announces the new cap in October for the following year. If you work for multiple employers in the same year, each one withholds Social Security tax independently up to the cap, which can result in overpayment. You recover the overpayment when you file your tax return.

How to calculate Medicare tax on your paycheck

Medicare tax is simpler than Social Security tax because it has no wage cap. You pay 1.45% of all your wages, no matter how much you earn. Multiply your gross pay by 0.0145 to find the Medicare tax amount.

On a $2,000 paycheck, Medicare tax is $2,000 × 0.0145 = $29. This calculation stays the same whether you earn $30,000 or $300,000 in a year. However, if your wages exceed certain thresholds, an additional Medicare tax of 0.9% applies. 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. Your employer withholds this additional tax automatically once you cross the threshold.

Additional Medicare tax for high earners

If your wages exceed $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately), you owe an additional 0.9% Medicare tax on the amount above the threshold. This is separate from the standard 1.45% Medicare tax and has no employer match — you pay the full 0.9% yourself.

Your employer withholds this tax automatically once you cross the threshold in a calendar year. The withholding is based on your wages alone, not your spouse's income, even if you file jointly. If you work for multiple employers and your combined wages exceed the threshold, you may overpay this tax. You recover the overpayment when you file your return and claim a credit for the excess.

FICA calculations for self-employed workers

Self-employed workers pay both the employee and employer portions of FICA, totaling 15.3% for Social Security (12.4%) and Medicare (2.9%). You calculate this on your net self-employment income, which is your business income minus business expenses, then reduced by half of your self-employment tax itself.

The calculation is more complex than a W-2 employee's because you start with Schedule C (Profit or Loss from Business) on your tax return. You transfer your net profit to Schedule SE (Self-Employment Tax), where you explore the 15.3% rate. The Social Security portion still has the annual wage cap — for 2024, that is $168,600 of net self-employment income. The Medicare portion has no cap, but the additional 0.9% Medicare tax applies to net self-employment income above the same thresholds as W-2 wages.

You pay self-employment tax quarterly using Form 1040-ES, or you can pay it all at once when you file your annual return. Many self-employed workers set aside 25% to 30% of their net income to cover both income tax and self-employment tax combined.

Reading your pay stub to verify FICA withholding

Your pay stub shows FICA withholding in separate line items, usually labeled "Social Security Tax" and "Medicare Tax" or abbreviated as "FICA SS" and "FICA Med." The amount withheld should match your gross pay multiplied by the tax rates, minus any wages already withheld that year if you are near the Social Security wage cap.

Check that the gross pay amount is correct — this is the starting point for all FICA calculations. Then verify the Social Security tax is 6.2% of gross pay (or zero if you have already hit the wage cap). Verify Medicare tax is 1.45% of gross pay, plus 0.9% if your year-to-date wages exceed the threshold. If the amounts do not match, contact your payroll department. Common errors include incorrect gross pay, failure to stop Social Security withholding after the wage cap, or incorrect additional Medicare tax thresholds.

What happens if you overpay FICA tax

Overpayment of FICA tax most often happens when you work for multiple employers in the same year. Each employer withholds Social Security tax independently up to the $168,600 wage base, so if you earn $100,000 at Job A and $100,000 at Job B, you will pay Social Security tax on both amounts even though your combined wages exceed the cap.

You recover the overpayment by filing your tax return. On Form 1040, you report all your W-2 wages and all the FICA tax withheld. The IRS calculates the correct amount of Social Security tax you should have paid and issues a refund for the overpayment. You do not need to do anything special — the IRS catches this automatically when you file.

Overpayment of additional Medicare tax can also occur if you work for multiple employers and your combined wages exceed the threshold. You claim a credit for the excess additional Medicare tax on Form 8959 (Additional Medicare Tax) when you file your return.

Frequently Asked Questions

Does FICA tax explore to all types of income?

FICA tax applies to wages and self-employment income. It does not explore to investment income, rental income, or most other sources. If you receive a 1099 form for contract work, you owe self-employment tax on that income. If you receive a 1099 for interest or dividends, you do not owe FICA tax on it.

What is the Social Security wage base and why does it matter?

The wage base is the maximum amount of annual earnings subject to Social Security tax. For 2024, it is $168,600. Once you earn that amount in a calendar year, no more Social Security tax is withheld from your paychecks. The base increases most years to account for wage growth in the economy.

Can I reduce my FICA tax withholding?

No. FICA tax rates are set by federal law and explore to all employees and self-employed workers. You cannot reduce the percentage withheld or claim exemptions. Your W-4 form controls income tax withholding, not FICA tax.

If I am married filing jointly, how does the additional Medicare tax threshold work?

The threshold is $250,000 of combined wages for married couples filing jointly. Your employer withholds the additional 0.9% Medicare tax based on your individual wages, not your spouse's. If your wages alone exceed $200,000, your employer will withhold it. You sort out the correct amount when you file your return together.

How do I calculate FICA tax if I have both W-2 and self-employment income?

You report W-2 wages on Form 1040 and self-employment income on Schedule C and Schedule SE. The Social Security wage cap applies to your combined W-2 and self-employment income. If your W-2 wages already reach the cap, you do not owe Social Security tax on self-employment income. Medicare tax applies to both with no cap, plus the additional 0.9% if your combined income exceeds the threshold.