FICA is calculated as a percentage of your gross wages, taken directly from your paycheck before you see the money

FICA — Federal Insurance Contributions Act — taxes fund Social Security and Medicare. Your employer withholds these taxes from each paycheck using a straightforward percentage formula. Unlike income tax, which depends on your filing status and deductions, FICA is the same percentage for almost everyone, regardless of how much you earn or what else is on your tax return.

The calculation happens in two parts: Social Security tax and Medicare tax. Each has its own rate and its own wage limit. Your employer does the math automatically, but understanding how it works helps you read your pay stub and plan for what you'll owe at tax time.

Key Takeaways

  • Social Security tax is 6.2% of your wages up to a wage cap that changes each year, while Medicare tax is 1.45% with no wage limit.
  • Your employer withholds both taxes from your paycheck and also pays an equal amount on your behalf, so the total cost to your employer is double what you see withheld.
  • Self-employed people pay both the employee and employer share, which totals 15.3%, but can deduct half of it on their tax return.
  • High earners pay an additional 0.9% Medicare tax on wages above a threshold that depends on filing status.
  • FICA withholding appears on your pay stub as separate line items and is never refundable, even if you owe no income tax.

The Social Security portion: 6.2% up to the wage cap

Social Security tax is withheld at 6.2% of your wages, but only up to a maximum amount per year. That maximum is called the wage base, and it increases most years to account for inflation. For 2024, the wage base is $168,600, meaning you pay Social Security tax on the first $168,600 you earn in the year, then nothing on wages above that.

This is why high earners see their Social Security withholding stop partway through the year. If you earn $200,000 in salary, you pay 6.2% on $168,600 (which is $10,453.20), and then your employer stops withholding Social Security tax for the rest of the year. Medicare tax, by contrast, continues on every dollar.

If you work for multiple employers in the same year, each one withholds Social Security tax independently. If your combined wages exceed the wage base, you may over-withhold and can claim a credit on your tax return. The IRS Form 1040 has a line for this adjustment.

The Medicare portion: 1.45% with no wage limit

Medicare tax is simpler: 1.45% of all your wages, with no upper limit. Unlike Social Security, there is no wage cap. Whether you earn $50,000 or $500,000, you pay 1.45% on every dollar.

However, there is an additional Medicare tax for high earners. If your wages exceed $200,000 (single filer), $250,000 (married filing jointly), or $125,000 (married filing separately), you pay an extra 0.9% Medicare tax on the amount above the threshold. This additional tax is also withheld by your employer if your wages cross the threshold during the year.

How your pay stub shows the calculation

On your pay stub, you will see separate line items for Social Security and Medicare withholding. The label might say "OASDI" (Old Age, Survivors, and Disability Insurance — the formal name for Social Security) or straightforward "SS Tax" or "Social Security." Medicare withholding is usually labeled "Medicare Tax" or "HI" (Hospital Insurance).

To verify the math yourself: multiply your gross pay (before any deductions) by 6.2% for Social Security and 1.45% for Medicare. The result should match what appears on your stub. If you earn above the Social Security wage base, the Social Security withholding will be lower than 6.2% of gross pay because it only applies to wages below the cap.

Your pay stub also shows what your employer is paying on your behalf, though this amount does not come out of your check. The employer's share is the same: 6.2% for Social Security and 1.45% for Medicare. This is why the total FICA cost to your employer is 15.3% of your wages (6.2% + 1.45% on each side), even though you only see 7.65% withheld from your paycheck.

Self-employed FICA: paying both sides

If you are self-employed, you pay both the employee and employer share of FICA on your net self-employment income. That totals 15.3% (12.4% for Social Security up to the wage base, plus 2.9% for Medicare). You calculate this on Schedule SE (Self-Employment Tax), which is part of your annual tax return.

The good news: you can deduct half of your self-employment tax on your tax return. This deduction reduces your taxable income and partially offsets the higher FICA burden. The deduction appears on Form 1040 and is calculated automatically if you use tax software or work with a tax professional.

Self-employed people also have to make quarterly estimated tax payments, which include both income tax and self-employment tax. These are due on April 15, June 15, September 15, and January 15 of the following year.

FICA withholding versus income tax withholding

FICA and income tax are two separate systems. FICA is a fixed percentage with a wage cap (for Social Security). Income tax withholding depends on your W-4 form, your filing status, and the number of dependents you claim. You can adjust your income tax withholding by changing your W-4, but you cannot change your FICA withholding — it is set by law.

Another key difference: FICA is never refundable. Even if you owe no federal income tax and receive a refund, your FICA withholding stays with the government. It funds your future Social Security and Medicare benefits. Income tax that you overpay can be refunded to you, but FICA cannot.

What happens if you change jobs mid-year

When you change jobs, each employer withholds FICA independently based on the wages they pay you. If your total wages across all employers exceed the Social Security wage base, you may over-withhold on Social Security tax. For example, if you earn $100,000 at Job A and then $80,000 at Job B, you pay Social Security tax on all $180,000 even though the wage base is $168,600.

To recover the over-withholding, you claim it as a credit on your tax return. On Form 1040, there is a line for "excess Social Security tax withheld." You will need to add up the Social Security tax from all your W-2 forms and compare it to what you should have paid based on the wage base. The difference is your refundable credit.

Frequently Asked Questions

Why do I pay FICA if I might not collect Social Security?

FICA funds current retirees and disabled workers, not just your own future benefits. You are required to contribute regardless of whether you expect to collect. If you die before retirement, your family may receive survivor benefits. If you become disabled, you may receive benefits before retirement age.

Can I opt out of FICA?

No. FICA withholding is mandatory for all employees and self-employed people. The only exception is certain religious groups that have received an IRS exemption, which requires a formal process and approval process.

Does FICA withholding count toward my income tax?

No. FICA and income tax are separate. FICA withholding does not reduce the amount of income tax you owe. However, if you are self-employed, you can deduct half your self-employment tax, which lowers your taxable income.

What if my employer did not withhold FICA?

Contact your employer when ready. They are required by law to withhold and remit FICA taxes. If they failed to do so, you may still owe the tax, and your employer may face penalties. The IRS can help you report non-compliance.

How do I know how much FICA I have paid so far this year?

Your pay stub shows FICA withholding for that pay period and often a year-to-date total. You can also check your Social Security account at ssa.gov, which displays your earnings record and estimated benefits. Your W-2 form, issued in January, shows total FICA withheld for the previous year.