What FICA taxes are and why they're taken from your paycheck

FICA stands for the Federal Insurance Contributions Act. It is the law that requires your employer to withhold money from your paycheck for two programs: Social Security and Medicare. These are not optional deductions — they come out of every paycheck if you work as an employee, and the amount is set by federal law, not by your employer or your tax bracket.

The money withheld goes into trust funds that pay benefits to people who are retired, disabled, or receiving Medicare. When you work, you are paying into the system. When you retire or become unable to work, you draw from it. The amount you pay now also affects how much you will receive later.

Self-employed people pay FICA too, but they calculate and send it themselves rather than having an employer withhold it. The rate is higher for self-employed workers because they pay both the employee and employer share.

Key Takeaways

  • Social Security tax is 6.2% of your wages up to a yearly cap (the cap changes each year), and Medicare tax is 1.45% of all wages with no cap.
  • Your employer withholds both amounts from your paycheck and sends them to the government, so you see the deduction on your pay stub.
  • Self-employed people pay 12.4% for Social Security (up to the yearly cap) and 2.9% for Medicare, calculated on their net business income.
  • High earners may owe an additional 0.9% Medicare tax on wages above a threshold, which varies by filing status.
  • The Social Security wage cap changes yearly; in 2024 it was $168,600, meaning you stop paying Social Security tax once you reach that amount in a calendar year.

How the Social Security portion is calculated

Social Security tax is 6.2% of your gross wages, but only up to a yearly limit called the wage base. In 2024, that limit was $168,600. This means if you earn $168,600 or more in a year, you pay 6.2% on the first $168,600 and nothing on anything above that. If you earn $100,000, you pay 6.2% on the full $100,000.

The wage base changes every January based on national wage trends. If you change jobs mid-year, each employer withholds based on what you earn at that job, so you might overpay if your combined earnings cross the cap. You can claim the overpayment back when you file your tax return.

To find the exact wage base for the current year, check the Social Security Administration website. The number is published in October of the prior year.

How the Medicare portion is calculated

Medicare tax is 1.45% of all your wages with no yearly cap. Unlike Social Security, there is no limit — you pay 1.45% on every dollar you earn, whether you make $30,000 or $300,000.

However, high earners owe an additional Medicare tax of 0.9% on wages above a threshold. The threshold depends on your filing status: $200,000 if you file as single, $250,000 if you file as married filing jointly, and $125,000 if you file as married filing separately. Once your wages cross that threshold in a year, you owe the extra 0.9% on everything above it.

Your employer is required to withhold the additional 0.9% Medicare tax once you cross the threshold at that job. If you have multiple jobs, each employer withholds based only on what you earn there, so you might overpay. Again, you can claim the overpayment on your tax return.

What appears on your pay stub

Your pay stub will show FICA withholding broken into two line items: one for Social Security and one for Medicare. You will see the dollar amount withheld, not just the percentage. The stub may also show year-to-date totals, which helps you track whether you are approaching the Social Security wage cap.

If you have multiple jobs, each pay stub shows only the withholding from that employer. Your total FICA payment across all jobs may be higher than if you worked one job, because each employer withholds independently without knowing about your other income.

Check your pay stub against the calculation: multiply your gross pay by 6.2% for Social Security (or 0% if you have already hit the wage cap) and by 1.45% for Medicare, plus 0.9% if you are above the high-earner threshold. If the numbers do not match, contact your payroll department.

How self-employed people calculate FICA

If you are self-employed, you pay self-employment tax, which is the self-employed version of FICA. You owe 12.4% for Social Security (up to the yearly wage base) and 2.9% for Medicare (no cap), calculated on your net business income — that is, your revenue minus your business expenses.

You calculate self-employment tax on Schedule SE, which you file with your tax return. The Social Security portion is still subject to the yearly cap, so once your net income reaches $168,600 (in 2024), you stop owing the 12.4% and pay only the 2.9% Medicare tax on income above that.

Self-employed people also get a deduction: you can deduct half of your self-employment tax from your income before calculating your income tax. This partially offsets the fact that you pay both the employee and employer share.

What happens if you overpay FICA

Overpayment happens most often when you change jobs mid-year or have multiple jobs. If your combined earnings from all sources exceed the Social Security wage base, you will have paid more than the law requires.

You cannot get the overpayment back directly from your employer. Instead, you claim it on your federal tax return using Form 1040. The IRS will refund the overpaid amount or credit it against taxes you owe. You file your return the following year, so the refund comes then, not immediately.

Self-employed people who overpay self-employment tax also claim the overpayment on their return. Keep records of your income from all sources so you can calculate the correct amount.

How FICA affects your future benefits

The FICA taxes you pay now determine two things: whether you are covered by Social Security and Medicare, and how much you will receive when you claim benefits.

Social Security calculates your benefit based on your 35 highest-earning years. The more you earn and pay into the system, the higher your benefit will be. If you do not work long enough to accumulate 40 credits (roughly 10 years of work), you will not be covered by Social Security retirement benefits, though you may still be covered by disability or survivor benefits under different rules.

Medicare coverage is based on your work history too. If you or your spouse paid Medicare tax for at least 10 years, you are covered by Medicare Part A (hospital insurance) at age 65 with no premium. If you have not worked long enough, you can still buy into Medicare, but you will pay a higher premium.

Frequently Asked Questions

What is the difference between FICA and income tax withholding?

FICA and income tax are two separate withholdings. FICA funds Social Security and Medicare and is a fixed percentage set by law. Income tax withholding is based on your W-4 form and varies by how much you earn and how many dependents you claim. 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 withholding is required by law for all employees and self-employed people. The only narrow exceptions are certain religious groups and some government employees with their own pension systems, and those exceptions require specific certification. If you are a regular employee, you must pay FICA.

Why do I owe more FICA when I file my taxes if my employer already withheld it?

This usually means you are self-employed or have income your employer did not withhold from. Self-employed people owe self-employment tax on top of income tax. If you have both W-2 income and self-employment income, you may owe additional FICA on the self-employment portion. Calculate what you owe on Schedule SE and pay it with your return.

Does FICA withholding count toward my income tax?

No. FICA and income tax withholding are separate. FICA does not reduce the income tax you owe. However, if you overpaid income tax during the year, you get a refund of that overpayment. FICA overpayment is handled separately and also refunded, but only if you file a return and claim it.

What happens to FICA if I work for a nonprofit or government employer?

Most nonprofit and government employees pay FICA the same way as private employees. Some government workers have their own pension systems and do not pay Social Security tax, but they still pay Medicare tax. Check with your employer's payroll department if you are unsure whether FICA is being withheld from your pay.