The Basics of Social Security and Medicare Payroll Taxes
Social Security and Medicare are primarily funded by dedicated payroll taxes shared between workers and their employers under rules set by federal law.
Workers pay 6.2 percent of their wages for Social Security — also called OASDI — on earnings up to the annual taxable wage maximum, which is 168,600 dollars in 2024 and adjusts each year based on national wage growth.
For Medicare Hospital Insurance (Part A), workers pay an additional 1.45 percent on all wages with no earnings cap, and employers match that 1.45 percent, bringing the combined standard payroll tax rate for employees to 7.65 percent of wages.
Self-employed individuals pay both the employee and employer shares, for a combined rate of 15.3 percent, though they can deduct half of that amount on their federal tax return.
How These Taxes Turn into Benefits
Social Security payroll taxes flow into two dedicated trust funds — the Old-Age and Survivors Insurance trust fund and the Disability Insurance trust fund — which pay benefits to about 71 million Americans, including most retirees receiving monthly checks.
The Medicare payroll tax finances Part A hospital coverage for seniors and certain disabled individuals, covering inpatient hospital stays, skilled nursing facility care after a qualifying hospital stay, and some home health services.
These taxes do not go into individual accounts for each worker; instead, today's workers and employers largely fund the benefits of today's retirees under a pay-as-you-go structure, while trust fund reserves serve as a buffer during periods when outflows exceed inflows.
Your future Social Security benefit is calculated from your highest 35 years of indexed earnings — the payroll taxes you and your employers contribute build both your eligibility and the overall trust fund balance that supports all beneficiaries.
Key insight: Every paycheck during your working years sends 7.65 percent of wages — 6.2 percent for Social Security and 1.45 percent for Medicare — toward the programs that will likely fund a major share of your income and health coverage in retirement.
The Additional Medicare Tax for Higher Earners
Since 2013, higher-income workers have paid an extra 0.9 percent Medicare tax on wages above 200,000 dollars for single filers or 250,000 dollars for married couples filing jointly.
This additional tax is not matched by employers and goes directly to Medicare's financing, helping offset the growing cost of benefits as the baby boom generation moves through retirement.
If you are still working part-time in retirement and your wages plus other income exceed these thresholds, you may owe this extra 0.9 percent on the amount above the limit when you file your tax return.
Understanding this rule can help you plan estimated tax payments so you are not surprised by an unexpected tax balance in April.
What Happens When You Work in Retirement
If you work while collecting Social Security, you and your employer continue to pay payroll taxes on your wages even after benefits have started, contributing to the system for other beneficiaries.
These additional earnings can sometimes increase your Social Security benefit, because the agency reviews your record annually and may replace lower-earning years in your 35-year calculation with higher recent wages.
However, if you claim Social Security before full retirement age and your wages exceed the annual earnings test limit — 22,320 dollars in 2024 — some benefits may be temporarily withheld, though those withheld amounts can raise your payment once you reach full retirement age.
Understanding how payroll taxes and the earnings test interact can help you decide whether continued part-time work in early retirement is worth the tradeoff between current earnings and any short-term benefit reduction.
Why This Knowledge Strengthens Your Advocacy
Knowing that Social Security and Medicare are funded by dedicated payroll taxes — not general income taxes drawn from the full federal budget — can sharpen your voice when engaging with elected officials about protecting these programs.
Key policy levers Congress can adjust include the payroll tax rate, the Social Security taxable wage cap, the Medicare tax on higher earners, and the full retirement age, each of which directly affects the long-term solvency of both programs.
For Americans aged 55 to 75, Social Security and Medicare represent decades of contributions made through every paycheck, so staying informed about how those contributions are used is an important part of protecting your financial security in the years ahead.
Related reading: full retirement age · protect your benefits