How FICA Taxes Work: Social Security & Medicare Explained

If you have ever looked at your pay stub and wondered why so much money disappears before you see it, FICA taxes are a big part of the answer. For most American workers, FICA taxes represent a larger deduction than federal income tax, yet many people don't fully understand what they are paying for or how the amounts are calculated.

FICA stands for the Federal Insurance Contributions Act. It is the law that authorizes payroll taxes to fund Social Security and Medicare, two of the largest federal programs in the United States. Unlike income tax, which varies based on your bracket, FICA taxes are a flat percentage of your gross earnings, making them straightforward to calculate but also regressive in nature.

The Two Components of FICA

FICA is split into two distinct taxes, each funding a separate program:

1. Social Security Tax (OASDI)

The Social Security tax, formally called Old-Age, Survivors, and Disability Insurance (OASDI), funds retirement benefits, disability benefits, and survivor benefits. As an employee, you pay 6.2% of your gross wages toward Social Security, and your employer pays a matching 6.2%, for a combined total of 12.4%.

There is a critical detail: the Social Security tax only applies to earnings up to the wage base limit, which is $176,100 for 2025. Once your year-to-date earnings exceed this threshold, you stop paying Social Security tax for the remainder of the year. This is why you might notice a bump in your take-home pay later in the year if you are a high earner.

For someone earning exactly $176,100, the maximum Social Security tax is $10,918.20 (6.2% of $176,100). If you earn more than the wage base, you pay the same maximum amount as everyone else at that level.

2. Medicare Tax

The Medicare tax funds the Medicare health insurance program for Americans age 65 and older (and certain younger people with disabilities). Employees pay 1.45% of all gross wages, and employers match with another 1.45%, for a combined rate of 2.9%.

Unlike Social Security, there is no wage base limit on Medicare tax. Every dollar you earn is subject to the 1.45% Medicare tax, regardless of how high your income goes.

Additional Medicare Tax for High Earners

Since 2013, high-income earners pay an extra 0.9% Additional Medicare Tax on wages above certain thresholds. This surtax is paid by the employee only; employers do not match it.

The thresholds depend on your filing status:

Single or Head of Household: wages over $200,000
Married Filing Jointly: combined wages over $250,000
Married Filing Separately: wages over $125,000

Your employer is required to start withholding the Additional Medicare Tax once your individual wages exceed $200,000, regardless of your filing status. If you are married filing jointly and your combined wages exceed $250,000 but neither spouse individually exceeds $200,000, you may owe Additional Medicare Tax when you file your return.

For example, a single filer earning $250,000 would pay 1.45% Medicare tax on all $250,000 ($3,625) plus 0.9% on the amount over $200,000 ($450), for a total Medicare tax of $4,075.

FICA Rates at a Glance (2025)

Social Security: 6.2% on wages up to $176,100 (employee share)
Medicare: 1.45% on all wages (employee share)
Additional Medicare: 0.9% on wages over $200,000 (employee only)
Total employee FICA (under $176,100): 7.65%
Total employer match: 7.65% (6.2% SS + 1.45% Medicare)
Combined employee + employer: 15.3%

How Employer Matching Works

Your employer pays the exact same FICA rate you do: 6.2% for Social Security and 1.45% for Medicare. This money does not come out of your paycheck. It is an additional cost the employer pays on top of your salary.

For a worker earning $80,000 per year:

Employee Social Security: $4,960 (6.2% x $80,000)
Employee Medicare: $1,160 (1.45% x $80,000)
Total employee FICA: $6,120
Employer pays matching: $6,120
Combined FICA cost: $12,240

The employer match is invisible on your pay stub, but it is a real cost of employment. This is why self-employed individuals pay the full 15.3% through self-employment tax, since they are both the employee and the employer.

Self-Employment Tax

If you are self-employed (freelancer, independent contractor, sole proprietor), you pay both the employee and employer portions of FICA through what is called the self-employment tax. The total rate is 15.3% (12.4% Social Security + 2.9% Medicare) on your net self-employment earnings.

The IRS provides some relief: you only pay self-employment tax on 92.35% of your net earnings (to account for the employer-equivalent portion), and you can deduct the employer-equivalent half of the self-employment tax from your adjusted gross income. This does not reduce your self-employment tax, but it does reduce your income tax.

What FICA Does Not Apply To

Certain types of income and situations are exempt from FICA taxes:

Investment income: Dividends, capital gains, and interest are not subject to FICA (though they may be subject to the 3.8% Net Investment Income Tax for high earners).
Pre-tax retirement contributions: Traditional 401(k) and 403(b) contributions reduce your federal income tax but are still subject to FICA. This is a common misconception.
HSA contributions via payroll: Health Savings Account contributions made through payroll deduction are exempt from both income tax and FICA tax, making HSAs one of the most tax-efficient savings vehicles available.
Certain student workers: Students working at the educational institution where they are enrolled may be exempt from FICA.

How FICA Affects Your Paycheck

Let's look at a real-world example. Say you earn $65,000 per year and are paid biweekly (26 pay periods). Your gross pay per paycheck is $2,500.

Social Security per paycheck: $155.00 (6.2% x $2,500)
Medicare per paycheck: $36.25 (1.45% x $2,500)
Total FICA per paycheck: $191.25
Annual FICA total: $4,972.50

That is nearly $5,000 per year in FICA taxes alone, before any federal or state income tax is taken out. To see your complete paycheck breakdown including all deductions, use our paycheck calculator.

Common Questions About FICA

Do I get the money back? Not directly. Your Social Security taxes fund current retirees. When you retire, future workers' FICA taxes will fund your benefits. Your benefit amount is based on your 35 highest-earning years.

Can I opt out of FICA? Generally no. FICA is mandatory for almost all employees and self-employed individuals. Very limited exemptions exist for certain religious groups and some government employees covered by alternative retirement systems.

What if my employer withheld too much? If you worked multiple jobs and your combined Social Security tax exceeded the maximum (because each employer withheld independently), you can claim the excess as a credit on your tax return.

The Bottom Line

FICA taxes are unavoidable for most workers, but understanding them helps you read your pay stub accurately and plan your finances. The 7.65% combined rate (6.2% Social Security + 1.45% Medicare) applies to every dollar you earn up to $176,100, after which only the Medicare portion continues. High earners pay an additional 0.9% Medicare surtax above $200,000.

For a complete breakdown of every deduction on your pay stub, read our guide on how to read your paycheck, or run your numbers through our paycheck calculator to see exactly how FICA and other taxes affect your take-home pay.