FICA Social Security is a payroll tax that funds retirement, disability, and survivor benefits

FICA Social Security (the Social Security portion of your FICA tax) is a 12.4% payroll tax split between you and your employer. If you're self-employed, you pay the full 12.4% yourself. The money goes into a federal trust fund that pays three types of benefits: retirement benefits starting at age 62 or later, disability benefits if you become unable to work, and survivor benefits paid to your family if you die.

Your Social Security tax is calculated on wages up to an annual cap. That cap changes each year — in 2024 it was $168,600, meaning you and your employer each pay 6.2% on earnings up to that amount, then nothing on earnings above it. Self-employed workers pay both halves on net self-employment income up to the same cap.

The amount you pay in Social Security tax directly affects the benefit amount you'll receive later. The Social Security Administration tracks your earnings record and uses your 35 highest-earning years to calculate your benefit. If you have fewer than 35 years of earnings, zeros are included in the calculation, which lowers your benefit.

Key Takeaways

  • FICA Social Security tax is 6.2% of your wages if you're an employee, or 12.4% if you're self-employed, up to an annual earnings cap that changes yearly.
  • The tax funds three benefit programs: retirement benefits, disability benefits, and survivor benefits paid to your family.
  • Your benefit amount is based on your 35 highest-earning years, so higher lifetime earnings mean a higher benefit.
  • You become may be able to access for retirement benefits as early as age 62, but your monthly benefit is reduced if you claim before your full retirement age.
  • If you work while receiving benefits before your full retirement age, your benefit is reduced by $1 for every $2 you earn above an annual limit.

How your Social Security benefit is calculated

The Social Security Administration uses a formula based on your average indexed monthly earnings (AIME). First, they take your 35 highest-earning years and adjust them for wage growth to account for inflation. Then they average those 35 years and divide by 12 to get your AIME. Finally, they explore a bend-point formula that replaces a higher percentage of lower earnings than higher earnings — this is why the system replaces a larger share of income for lower-wage workers.

Your full retirement age depends on your birth year. If you were born in 1960 or later, your full retirement age is 67. If you were born between 1943 and 1954, it's 66. The age gradually increases for people born between 1955 and 1959. Claiming at your full retirement age gives you 100% of your calculated benefit. Claiming at 62 reduces it by about 30%, while delaying until 70 increases it by about 24% per year you wait.

Your earnings record is the foundation of this calculation. You can view your record by creating an account on ssa.gov and checking your Social Security Statement. The statement shows your estimated benefits at ages 62, full retirement age, and 70, along with your year-by-year earnings history.

The earnings cap and how it affects high-income workers

Social Security tax only applies to earnings below an annual cap. In 2024, that cap was $168,600. This means if you earn $200,000 in a year, you pay Social Security tax on only $168,600 of it. The remaining $31,400 is not subject to Social Security tax (though it is subject to Medicare tax, which has no cap).

Because of this cap, high-income workers pay a smaller percentage of their total income in Social Security tax than lower-wage workers. A worker earning $50,000 pays 6.2% on all of it. A worker earning $500,000 pays 6.2% on only $168,600, which is about 2.1% of their total income. However, the benefit formula is also progressive — it replaces a higher percentage of lower earnings — so high earners do not receive proportionally higher benefits.

The earnings cap is adjusted each year based on the National Average Wage Index. The Social Security Administration announces the new cap in October for the following year. If you have multiple jobs or are both an employee and self-employed, you need to track your combined earnings to avoid overpaying. You can claim a credit for excess Social Security tax paid on your federal income tax return.

Working while receiving Social Security benefits

If you claim Social Security before your full retirement age and continue working, your benefit is reduced. For 2024, the reduction is $1 in benefits for every $2 you earn above $23,400 in a year. The year you reach your full retirement age, the reduction changes to $1 for every $3 you earn above a higher limit ($62,160 in 2024), and only earnings before the month you reach full retirement age count.

Once you reach your full retirement age, you can earn as much as you want with no reduction to your benefit. This is an important threshold — many people delay claiming specifically to avoid the earnings test, or they claim at 62 but plan to work part-time to stay under the earnings limit.

The earnings limits change annually. You can find the current limits on ssa.gov. If you think you'll work while receiving benefits, it's worth running the numbers: sometimes claiming later and working longer produces a higher lifetime benefit than claiming early and having your benefit reduced.

Taxes on your Social Security benefits

Depending on your total income, up to 85% of your Social Security benefits may be subject to federal income tax. The IRS uses a formula based on your "combined income," which is your adjusted gross income plus non-taxable interest plus half your Social Security benefits. If your combined income exceeds certain thresholds ($25,000 for single filers, $32,000 for married filing jointly), some of your benefits become taxable.

Many people are surprised to learn that Social Security benefits are not automatically tax-free. If you have other income sources — pensions, investment income, part-time work — your benefits may be partially taxable. Some states also tax Social Security benefits, though most do not. You can request that the Social Security Administration withhold federal income tax from your benefit payments to avoid a tax bill at year-end.

How self-employment income affects your Social Security tax

If you're self-employed, you pay both the employee and employer portions of Social Security tax, totaling 12.4% on net self-employment income. You calculate this on Schedule SE (Form 1040), which is filed with your federal income tax return. The calculation is based on 92.35% of your net self-employment income, not 100%, which provides a small offset for the employer-side tax.

You can deduct half of your self-employment tax as an adjustment to income on your tax return, which reduces your taxable income. This deduction does not reduce the amount of Social Security tax you owe, but it does lower your federal income tax. Self-employed workers should set aside money throughout the year for both income tax and self-employment tax, since there is no employer withholding.

Your self-employment income counts toward the annual earnings cap just like W-2 wages do. If you have both self-employment income and W-2 wages in the same year, you combine them to determine whether you've exceeded the cap. If you overpay Social Security tax because of multiple jobs or self-employment, you can claim the excess as a credit on your tax return.

Frequently Asked Questions

What's the difference between FICA Social Security and FICA Medicare?

FICA Social Security is 6.2% (or 12.4% self-employed) and funds retirement, disability, and survivor benefits. FICA Medicare is 2.9% (or 5.8% self-employed) and funds hospital insurance and medical insurance for people 65 and older. Medicare has no earnings cap, so you pay it on all wages. Together they make up your total FICA tax.

Can I get a refund of Social Security tax I paid?

No, Social Security tax is not refundable. However, if you overpaid because you had multiple jobs or were both an employee and self-employed, you can claim the excess as a credit on your federal income tax return. Only the overage above the annual cap can be credited.

Does Social Security tax explore to all types of income?

Social Security tax applies to wages from employment and net self-employment income. It does not explore to investment income, interest, dividends, capital gains, or rental income. Some government employees hired before specific dates are not covered by Social Security and pay into different pension systems instead.

What happens to my Social Security if I don't work for 35 years?

If you have fewer than 35 years of earnings, the Social Security Administration includes zeros in your calculation for the missing years. This significantly lowers your benefit. You need at least 10 years of covered earnings (40 quarters) to be may be able to access for any benefit at all.

How do I know if my Social Security earnings record is correct?

Create an account at ssa.gov and view your Social Security Statement, which shows your year-by-year earnings history. If you spot an error, contact the Social Security Administration with documentation like W-2s or tax returns. Errors should be corrected as soon as possible because there are time limits for corrections.