Payroll tax funds four specific federal programs, not general government spending
When you see "FICA" or "payroll tax" on your pay stub, that money goes to exactly four places: Social Security retirement benefits, Social Security disability insurance, Medicare hospital insurance, and Medicare medical insurance. Nothing else. The federal government cannot legally spend payroll tax on roads, defense, education, or any other program — it is segregated by law into those four trust funds.
Your employer also pays an equal amount on your behalf. Self-employed people pay both the employee and employer portions, which is why their total rate is roughly double what appears on a W-2 worker's stub. The money is collected by the IRS but immediately transferred to the Social Security Administration and the Centers for Medicare & Medicaid Services.
Key Takeaways
- Payroll tax is split four ways: Social Security retirement (6.2 percent of your wages), Social Security disability (included in the 6.2 percent), Medicare hospital insurance (1.45 percent), and Medicare medical insurance for high earners (0.9 percent on income above $200,000 single or $250,000 married).
- Your employer pays an identical amount for each category, so the total cost to hire you is your wage plus the full payroll tax.
- Payroll tax has a wage cap for Social Security but not for Medicare, meaning high earners pay a smaller percentage of total income into Social Security.
- The money sits in separate trust funds and cannot be spent on anything other than the four programs it funds.
Social Security retirement and disability are funded from the same tax
Social Security has two trust funds that draw from the same payroll tax: the Old-Age and Survivors Insurance fund (OASI) and the Disability Insurance fund (DI). Together they take 12.4 percent of your wages — 6.2 percent from you and 6.2 percent from your employer. The Social Security Administration decides how much goes to each fund based on how many people are drawing retirement versus disability benefits in any given year.
This shared funding means the two programs are not truly separate in practice. If more people draw disability benefits, less money flows to the retirement fund, and vice versa. Congress can shift money between the two funds if one runs low, but the total amount available is fixed at 12.4 percent of covered wages.
There is a wage cap: in 2024, you only pay Social Security tax on the first $168,600 of income. Anything you earn above that is not subject to the 12.4 percent tax. This means a person earning $200,000 pays the same dollar amount into Social Security as someone earning $168,600, even though they earn more. Your employer also stops paying their share once your wages hit the cap in a given year.
Medicare has two parts funded by payroll tax
Medicare Part A (hospital insurance) is funded by a 2.9 percent payroll tax — 1.45 percent from you and 1.45 percent from your employer. This covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Unlike Social Security, there is no wage cap on Medicare tax. You pay 1.45 percent on every dollar you earn, no matter how much.
Medicare Part B (medical insurance) is funded differently: it comes from general tax revenue and premiums paid by people enrolled in the program, not from payroll tax. However, there is an additional 0.9 percent Medicare tax on high earners that does come from payroll. If you earn more than $200,000 as a single filer or $250,000 as a married couple filing jointly, you pay an extra 0.9 percent on the income above those thresholds. Your employer does not pay this additional tax — it is on you alone.
The 0.9 percent high-earner tax was added in 2013 as part of the Affordable Care Act. It has no wage cap and applies to all income above the threshold, including investment income in some cases.
How much you actually pay depends on your income and filing status
For a typical employee earning $50,000 per year, payroll tax totals 7.65 percent of gross pay: 6.2 percent for Social Security and 1.45 percent for Medicare. Your employer pays another 7.65 percent on top of your salary. If you earn $200,000, you pay the same 7.65 percent on the first $168,600 (Social Security cap), then 1.45 percent on the remaining $31,400, plus an additional 0.9 percent on the $31,400 above the $200,000 threshold. The math gets more complex, but the key point is that high earners pay a lower percentage of total income into Social Security because of the wage cap.
The table below shows the breakdown of each tax component and where the wage caps apply:
| Tax Type | Your Rate | Employer Rate | Wage Cap (2024) |
|---|---|---|---|
| Social Security (retirement + disability) | 6.2% | 6.2% | $168,600 |
| Medicare Part A (hospital) | 1.45% | 1.45% | None |
| Medicare high-earner tax | 0.9% (over $200k single / $250k married) | None | None |
Self-employed people pay both the employee and employer share
If you are self-employed, you pay both sides of the payroll tax: 12.4 percent for Social Security and 2.9 percent for Medicare, totaling 15.3 percent. You also pay the 0.9 percent high-earner Medicare tax if your net self-employment income exceeds the thresholds. This is why self-employed tax liability is roughly double what a W-2 employee pays on the same income.
The IRS allows you to deduct half of your self-employment tax when calculating your adjusted gross income, which provides some offset. You report self-employment tax on Schedule SE and pay it quarterly using estimated tax payments, or you can pay it all when you file your annual return. Even with the deduction, self-employed workers bear the full cost of both the employee and employer portions.
Payroll tax revenue does not cover all benefits paid out
Both Social Security and Medicare Part A have trust funds that hold reserves. When payroll tax revenue exceeds the benefits paid out in a given year, the surplus goes into the trust fund. When benefits exceed revenue, the fund pays the difference from reserves. The Social Security trust fund is projected to be depleted around 2033 if Congress does not change the tax rate, the wage cap, or the benefit formula. Medicare Part A's trust fund faces a similar timeline.
This does not mean the programs will disappear. Once a trust fund is depleted, incoming payroll tax can still cover a portion of benefits — roughly 80 percent for Social Security and 89 percent for Medicare Part A, based on current projections. But without legislative action, benefits would be reduced unless revenue increases. The trust funds exist specifically to smooth out the difference between what comes in and what goes out each year.
Frequently Asked Questions
Does payroll tax go into the general federal budget?
No. Payroll tax is legally segregated into four trust funds and cannot be spent on anything else. The federal government has a separate general fund that pays for defense, infrastructure, and other programs. Payroll tax and general tax revenue are completely separate accounting systems.
Why is there a wage cap for Social Security but not Medicare?
Congress set the Social Security wage cap when the program began in 1935 to limit the maximum benefit someone could receive. The cap rises each year with inflation. Medicare has no cap because it was designed as a universal program for people over 65, not as an earnings-replacement program like Social Security. The high-earner tax added in 2013 was meant to shore up Medicare funding without raising the standard rate on all workers.
What happens to payroll tax if I change jobs?
Your new employer starts collecting payroll tax from your first paycheck. If you have already hit the Social Security wage cap in a given year, your new employer still collects 6.2 percent until the calendar year ends — you will get a refund when you file your tax return. Medicare tax continues regardless of job changes because there is no annual cap.
Can I opt out of paying payroll tax?
No, with very limited exceptions. Most workers must pay payroll tax. Some religious groups and self-employed people in certain situations can request exemption, but this is rare and requires IRS approval. If you do not pay payroll tax, you do not earn credits toward Social Security or Medicare benefits.
Is payroll tax the same as income tax?
No. Income tax is separate and goes into the general federal fund. Payroll tax is only for Social Security and Medicare. You pay both on wages, and they appear as separate line items on your pay stub. Self-employed people pay income tax and self-employment tax (payroll tax) separately.