Taxes withheld from your paycheck can sometimes be confusing, especially when it comes to Social Security and Medicare. While both are payroll taxes that fund vital federal programs, they differ significantly in how they apply to your earnings. Here’s what you need to know about their limits and rates.
Social Security Tax
Social Security tax is designed to fund retirement, disability, and survivor benefits. The tax rate is 6.2% for employees, with an equal 6.2% paid by employers, for a total of 12.4%. However, this tax has an annual earnings cap, known as the Social Security wage base limit.
For example, in 2025, the wage base is $168,600. This means that if you earn more than this amount, any additional income is not subject to Social Security tax. For high earners, this cap effectively limits the amount they contribute to the program each year.
Medicare Tax
Medicare tax is used to fund healthcare benefits for people aged 65 and older and certain individuals with disabilities. The standard Medicare tax rate is 1.45%, also matched by employers for a total of 2.9%. Unlike Social Security, there is no wage cap for Medicare tax—it applies to all earned income, regardless of the amount.
Additionally, high-income earners are subject to an extra 0.9% Medicare surtax. This surtax applies to wages exceeding $200,000 for single filers, $250,000 for married couples filing jointly, and $125,000 for married individuals filing separately. The surtax is not matched by employers, so employees are solely responsible for this additional amount.
Key Differences at a Glance
- Social Security tax is capped at the annual wage base limit, meaning only earnings up to this limit are taxed at the 6.2% rate.
- Medicare tax has no earnings cap and applies to all income, with an additional 0.9% surtax for high earners.
Why Does It Matter?
Understanding these differences can help you better anticipate your tax liabilities. For high-income individuals, the uncapped nature of Medicare tax and the additional surtax can significantly impact your paycheck. Meanwhile, the capped Social Security tax may mean lower contributions from those earning above the threshold.