To calculate FICA tax on a paycheck, multiply your gross taxable wages by 6.2% for Social Security and 1.45% for Medicare, for a combined 7.65%. Social Security stops applying once your year-to-date wages hit the annual wage base ($184,500 in 2026), and a 0.9% Medicare surtax gets added on wages above certain filing-status thresholds. Self-employed workers run a slightly different calculation, covered further down.
What Counts as FICA Wages
Before you multiply anything, you need the right number to multiply. FICA applies to gross taxable wages: base salary, overtime, bonuses, commissions, and tips.
Two common pre-tax deductions behave in opposite ways, and this is where paycheck math goes sideways:
- Contributions through a Section 125 cafeteria plan (health insurance premiums, FSAs, dependent care) are excluded from FICA wages. Those dollars lower both your income tax and your FICA tax.1Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans
- Traditional 401(k) contributions do not reduce FICA wages. Defer $10,000 from an $80,000 salary and you still owe FICA on the full $80,000.2Internal Revenue Service. 401(k) Plan Overview
Your pay stub usually shows the correct figure as “taxable earnings” or a similar label next to the FICA line.
The Social Security Calculation
Multiply your FICA-taxable wages for the pay period by 0.062. A $3,000 biweekly paycheck produces $186 of Social Security tax.3Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
That calculation runs every paycheck until your cumulative wages for the year reach the Social Security wage base. For 2026, the base is $184,500.4Social Security Administration. Contribution and Benefit Base Above that, you pay no more Social Security tax for the rest of the calendar year. The maximum any single employee owes in 2026 is $11,439 ($184,500 × 0.062).
If you cross the cap mid-paycheck, only the portion under the cap gets taxed. Say your year-to-date wages are $183,000 and your next check is $3,000. Social Security tax applies to the first $1,500, and the last $1,500 is exempt.5Office of the Law Revision Counsel. 26 USC 3121 – Definitions Withholding resets every January.
The Medicare Calculation
Medicare has no wage cap. Multiply every dollar of FICA wages by 0.0145. On a $3,000 paycheck, that’s $43.50.3Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
The 0.9% Additional Medicare Tax
An extra 0.9% applies to wages above these thresholds:6Office of the Law Revision Counsel. 26 USC 3101 – Rate of Tax
- Single or head of household: $200,000
- Married filing jointly: $250,000
- Married filing separately: $125,000
The surtax only touches wages above your threshold. A single filer earning $230,000 pays 1.45% on the full $230,000 plus 0.9% on the $30,000 above $200,000, an extra $270 for the year.
Employer withholding follows a single rule regardless of filing status: they start withholding the extra 0.9% once your wages with that employer pass $200,000 in a calendar year.7Internal Revenue Service. Topic No. 560, Additional Medicare Tax If you file jointly and your individual wages stay under $200,000 while combined household wages top $250,000, you’ll owe the surtax at tax time. If you file separately with a $125,000 threshold, employer withholding won’t start until $200,000, so you’ll settle up on your return.
Adding Up the Paycheck
Per pay period, add the Social Security amount to the Medicare amount (plus surtax if it applies). For most workers earning under $184,500, the combined FICA rate stays flat at 7.65% all year.
Your employer separately matches the 6.2% and the 1.45%, doubling what flows into each program.8Office of the Law Revision Counsel. 26 USC 3111 – Rate of Tax Employers do not match the 0.9% surtax; that piece is entirely on the employee.7Internal Revenue Service. Topic No. 560, Additional Medicare Tax
Check your calculation against the FICA line on your pay stub every few periods. Bonuses and mid-year raises that push you near the Social Security cap are common sources of payroll errors.
If You Have Two Jobs
Each employer withholds Social Security tax on the first $184,500 of wages they pay you, with no visibility into what the other employer already withheld. If your combined wages exceed the cap, you overpay.4Social Security Administration. Contribution and Benefit Base
You recover the excess as a credit on Form 1040, following the “Excess Social Security and Tier 1 RRTA Tax Withheld” instructions.9Internal Revenue Service. Topic No. 608, Excess Social Security and RRTA Tax Withheld Medicare has no cap, so there is nothing to reclaim on that side.
If You’re Self-Employed
Self-employment tax under SECA covers both halves: 12.4% Social Security plus 2.9% Medicare, for a combined 15.3%.4Social Security Administration. Contribution and Benefit Base
You don’t apply that rate to your full net profit. First, multiply net self-employment earnings by 0.9235 to get the taxable base. That step mirrors the fact that W-2 employees don’t pay FICA on their employer’s share.10Internal Revenue Service. Topic No. 554, Self-Employment Tax
Worked on $100,000 of net self-employment income:
- Taxable base: $100,000 × 0.9235 = $92,350
- Social Security: $92,350 × 12.4% = $11,451.40
- Medicare: $92,350 × 2.9% = $2,678.15
- Total self-employment tax: $14,129.55
The $184,500 Social Security cap still applies to self-employment earnings, and the 0.9% Additional Medicare Tax kicks in at the same filing-status thresholds. File Schedule SE if your net self-employment earnings are $400 or more.11Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) You can then deduct half of your self-employment tax when calculating adjusted gross income on Form 1040, which lowers your income tax without reducing the SE tax itself.10Internal Revenue Service. Topic No. 554, Self-Employment Tax
A Note on Exemptions
Almost every worker owes FICA. Two narrow exemptions exist and don’t affect the calculation for typical employees. Students enrolled at least half-time who work for their own school in a job incidental to their studies may be exempt.12Internal Revenue Service. Student FICA Exception Members of recognized religious groups that conscientiously oppose insurance benefits can apply on Form 4029, which permanently waives Social Security and Medicare benefits along with the tax.13Internal Revenue Service. Form 4029, Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits If neither applies to you, run the standard calculation above.