How To Calculate Social Security Tax

Social Security tax and Medicare tax are the two payroll taxes that fund the federal retirement and health programmes. Together they are known as FICA, and they are withheld from every paycheck by the employer.

The Social Security portion is charged at 6.2 percent of wages, but only up to an annual wage base. Earnings above that base are not subject to the tax, which is why the effective rate falls as income rises past the cap.

The wage base is adjusted most years for wage growth. For 2026 it is 176,100 dollars, and it is worth confirming the current figure before relying on a calculation, because using an out-of-date base misstates the tax.

The Medicare portion is charged at 1.45 percent of all wages with no cap. Because it applies to every dollar earned, it becomes a larger share of the total payroll tax at higher incomes.

An additional Medicare tax of 0.9 percent applies above a threshold, which is 200,000 dollars for a single filer and 250,000 for a married couple filing jointly. It is charged only on the amount above the threshold.

The employer matches the Social Security and standard Medicare contributions, so the total paid into the system is double what the employee sees withheld. Self-employed people pay both halves, which is why self-employment tax is higher.

The effective rate is the total FICA divided by wages. It rises from about 7.65 percent at low incomes to just over 8 percent once the additional Medicare tax applies, and it dips relative to income once wages pass the Social Security base.

Because the Social Security tax stops at the base, the marginal rate on the next dollar of wages above the base is just 1.45 percent plus any additional Medicare tax. That is a sharp change from the rate below the base.

Withholding is applied per paycheck against an annualised estimate, so an employee with two jobs or a mid-year job change can under-withhold and owe the difference at filing. The additional Medicare tax is particularly prone to this.

Social Security benefits are based on lifetime covered earnings, so the tax is not simply a cost. The link between contributions and benefits is indirect, but the earnings record determines the eventual benefit.

Deductions from gross pay for retirement plans, health insurance and other pre-tax benefits usually reduce taxable wages for income tax but not for FICA. That is why FICA is often larger than people expect relative to taxable income.

The tax is charged on wages rather than on total income, which matters for people who also receive investment income, rental income or self-employment profit. Only the wage portion is subject to FICA, while the other income is subject to income tax and possibly the net investment income tax instead.

Checking the Social Security earnings record each year is worth the few minutes it takes. The record determines the eventual benefit, and errors are far easier to correct while the employer still has the payroll data than decades later.

The calculator models the figures entered and nothing more. It does not know your filing status, other jobs or any treaty position. Treat the output as the FICA on the wages entered and confirm the wage base for the year in question.