How much is FICA tax?

6.2% for Social Security plus 1.45% for Medicare on your wages, withheld from every paycheque, with your employer paying the same amounts again on top. The Social Security half stops once your wages for the year reach the annual wage base; the Medicare half never stops. Enter your wages above and the panel shows each component separately, with the combined employee-plus-employer figure underneath.

Is there a limit on how much Social Security tax I pay?

Yes, and it is a ceiling on the earnings the tax applies to rather than on the tax itself. Once your year-to-date wages reach the annual wage base, no further Social Security tax is charged for that year, and the deduction restarts in January. Medicare has no equivalent ceiling — it continues at 1.45% on every dollar, and is joined by the 0.9% surtax higher up.

Why is self-employment tax so much higher than payroll tax?

Because you pay both halves. An employee pays 6.2% and 1.45% while the employer pays a matching 6.2% and 1.45%; a self-employed person is both parties, so the rate is 15.3% — 12.4% plus 2.9%. Two things soften it: the tax applies to 92.35% of net earnings rather than all of them, and half of what you pay is deductible above the line against income tax.

I have a job and a side business — do I pay Social Security tax twice?

No. The annual wage base is per person, not per source. Your wages count against it first, and only the part of your net self-employment earnings that still fits underneath is charged the 12.4%. Medicare works differently: it applies at 1.45% on wages and 2.9% on net earnings with no ceiling on either, so both are charged in full no matter how the income is split.

What is the additional 0.9% Medicare tax?

A surtax on wages plus net self-employment earnings above a threshold that depends on your filing status. Your employer must start withholding it once it has paid you past a fixed amount, but it cannot see a spouse’s income or your business, so the amount withheld and the amount owed routinely differ and the balance is settled on your return. Because the thresholds are statutory and unindexed, they reach further down the income distribution each year.

Does the employer’s half really come out of my pay?

Not from your payslip, but it is part of what you cost to employ, and the weight of the economic evidence is that the burden lands largely on wages over time. The practical use is comparison: a contract rate that has to absorb 15.3% of self-employment tax is not equivalent to a salary of the same number, and the combined line in the panel is the size of that gap.

FICA Tax Calculator — Social Security & Medicare

Where the tax comes from

Each component with the rate charged, the amount of income it is actually charged on, and what that produces. The base column is the one worth reading — it is rarely your whole income.

Social Security, Medicare and self-employment tax on $85,000 of wages and $0 of net self-employment income.
Component	Rate	Applied to	Amount
Social Security	6.20%	$85,000	$5,270
Medicare	1.45%	$85,000	$1,233
Additional Medicare tax	0.90%	$0	$0
Self-employment tax	15.30%	$0	$0
Total	—	$85,000	$6,503

Employee side only — the employer’s matching contribution is shown in the panel above, not in this table. The self-employment row is charged on 92.35% of the income you entered, and the additional Medicare row only on the amount above the threshold for your filing status.

The annual wage base caps Social Security only. Medicare keeps taking 1.45% of every dollar above it, so your FICA deduction never drops to zero.
You get one Social Security wage base per person, not one per income source. Wages fill it first, and only what is left is available to your self-employment earnings.
The 0.9% surtax thresholds are written into statute and are not indexed to inflation, so a slightly larger share of earners crosses them every year.
The employer’s matching 6.2% and 1.45% is part of what you cost to employ even though it never appears on your payslip — count it when you compare a salary against a contract rate.

How the FICA calculator works

FICA is two separate taxes collected as one deduction, and they behave differently. Social Security is charged at 6.2% of your wages, but only up to an annual wage base — once your year-to-date wages pass that ceiling, the deduction stops for the rest of the year. Medicare is charged at 1.45% on every dollar of wages, with no ceiling at all. Enter your wages and the calculator applies both, and shows the identical 6.2% and 1.45% your employer pays alongside them.

Self-employment income is charged under a different name and at a different rate, because there is no employer to pay the other half. Self-employment tax is 15.3% — 12.4% for Social Security and 2.9% for Medicare, both halves — and it applies to 92.35% of your net self-employment earnings rather than all of them. That 92.35% adjustment exists to put you in roughly the same position as an employee, whose employer half is not part of their own taxable wages. Half of the resulting tax is then deductible above the line, which the panel shows as its own row.

The third piece is the additional Medicare tax: an extra 0.9% on the amount by which your wages plus your net self-employment earnings exceed a statutory threshold set by filing status. It is employee-side only — there is no employer match on that part — and the calculator applies it to the combined figure rather than to each income type separately. That is the piece most calculators get wrong for anyone with both a job and a side business.

The math

Social Security tax is 6.2% of the lesser of your wages and the annual wage base. Medicare tax is 1.45% of your wages, full stop. Self-employment tax takes your net self-employment income, multiplies it by 92.35% to get net earnings, charges 12.4% on whatever part of those earnings still fits under the same wage base after your wages have used up their share of it, and charges 2.9% on all of them. There is one wage base per person, not one per income source, which is why the order matters.

The additional Medicare tax is computed once, on wages plus net self-employment earnings combined, against the single threshold for your filing status — not separately on each income, because someone under the threshold on wages alone and under it on a business alone can still be over it on the two together. Employers withhold it based only on what they themselves pay you, so what is withheld through the year is frequently not what is owed; the difference is settled on your return.

Two things sit outside this. Federal and state income tax are separate from FICA and are not computed here, so nothing on this page is a take-home figure. And the employer’s share is displayed rather than deducted — it never touches your payslip, but it is paid on your behalf out of whatever your employer budgeted to employ you.

Worked example

On $85,000 of wages filing single, Social Security takes $5,270 and Medicare takes $1,232.50, for $6,502.50 withheld across the year. Your employer pays the same $6,502.50 again, so $13,005 in total is collected on your work — a figure your payslip never shows you.

Add $40,000 of net self-employment income on top. Self-employment tax applies to 92.35% of it, or $36,940 of net earnings: 12.4% of that is $4,581 of Social Security and 2.9% is $1,071 of Medicare, a self-employment tax of $5,652, of which $2,826 comes back as an above-the-line deduction. Together with the payroll side, $12,154 is due on $125,000 of income, and no surtax applies because the combined figure is still under the threshold.

Now drag the wage slider upward. The Social Security line grows until wages reach the annual wage base and then stops dead, while Medicare keeps climbing at 1.45% indefinitely; further up, the 0.9% surtax begins and the marginal rate rises again. A rate that falls at one income and rises at another is why the effective percentage under the headline total is worth reading.

Key terms

Social Security wage base: The annual amount of earnings above which no further Social Security tax is charged. It applies to Social Security only, resets each calendar year, and is shared across your wages and your self-employment earnings.
Additional Medicare tax: An extra 0.9% charged on wages plus net self-employment earnings above a threshold set by filing status. There is no employer match on it, and the threshold is not adjusted for inflation.
Net earnings from self-employment: 92.35% of your net self-employment income. This, rather than the full amount, is the base that self-employment tax is actually charged on.
Employer match: The 6.2% and 1.45% your employer pays on your wages in addition to what is withheld from you. It is not deducted from your pay and does not appear on your payslip.

FICA Tax Calculator (US, 2026)