Social Security withholding is calculated by multiplying your taxable wages each pay period by 6.2%, up to an annual earnings cap of $184,500 in 2026.1Office of the Law Revision Counsel. 26 USC 3101 – Tax on Employees2Social Security Administration. Contribution and Benefit Base Your employer pays a matching 6.2% out of its own pocket, so 12.4% of every dollar you earn below the cap goes to Social Security.3Office of the Law Revision Counsel. 26 USC 3111 – Rate of Tax The arithmetic is simple. What makes the number on your stub hard to predict is which deductions come out before the 6.2% is applied and which do not.
The Basic Math on a Paycheck
Payroll runs the calculation each pay period: taxable wages times 0.062. Earn $4,000 in a biweekly pay period and your Social Security withholding is $248. Your employer sends another $248 alongside it. You never see the employer’s half, but it exists.
Both halves are remitted to the federal government on the employer’s regular deposit schedule. The employer’s contribution does not come out of your pay, so it does not change the calculation you see on your stub.
The 2026 Wage Cap
Social Security tax stops for the year once your year-to-date earnings with a single employer hit $184,500.2Social Security Administration. Contribution and Benefit Base At that point payroll stops the 6.2% withholding for the rest of the calendar year. The maximum any employee pays into Social Security in 2026 is $11,439 ($184,500 × 6.2%).
The cap resets every January and adjusts each year based on the national average wage index.4Office of the Law Revision Counsel. 42 USC 430 – Adjustment of Contribution and Benefit Base If you hit the cap in September and paid nothing on your last-quarter paychecks, your first paycheck in January is fully subject to withholding again.
If You Work Two Jobs
Each employer tracks your wages on its own. If your combined pay from two jobs exceeds $184,500, both will withhold Social Security tax on their share and you will overpay. You recover the excess by claiming a credit on Schedule 3 of your Form 1040.5Internal Revenue Service. Topic No. 608, Excess Social Security and RRTA Tax Withheld6Internal Revenue Service. Instructions for Form 1040 A single employer should never withhold past the cap; if yours does, that gets corrected through payroll, not on your tax return.
Which Deductions Actually Reduce the Calculation
The starting point is gross pay: hourly wages, salary, bonuses, and commissions. From there, some pre-tax deductions lower the wages that get multiplied by 6.2%, and some do not. This is where most confusion starts, because the rules for Social Security are not the same as the rules for federal income tax.
401(k) and 403(b) Contributions
Traditional 401(k) and 403(b) contributions reduce your federal income tax withholding, but they do not reduce your Social Security wages.7Internal Revenue Service. 401(k) Resource Guide Plan Participants 401(k) Plan Overview The 6.2% still applies to every dollar you defer. That is why your W-2 Social Security wages in Box 3 are typically higher than the income-tax wages in Box 1.
Health Insurance and Other Cafeteria Plan Benefits
Pre-tax benefits paid through a Section 125 cafeteria plan do reduce your Social Security wages. Health insurance premiums, dental and vision coverage, and health savings account contributions taken through salary reduction are excluded from FICA wages entirely.8Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans9Office of the Law Revision Counsel. 26 USC 3121 – Definitions If $500 a month comes out of your paycheck for employer-sponsored health coverage through a Section 125 plan, the 6.2% is calculated on $500 less than your gross. For most workers these benefit deductions are the only thing that actually shrinks the Social Security tax base.
Tips
Cash and credit card tips are Social Security wages and must be reported to your employer, who then withholds on them like regular pay. If your total tips from a single employer are under $20 in a calendar month, they do not need to be reported and are not subject to withholding.10Internal Revenue Service. Tip Recordkeeping and Reporting
Reading the Full FICA Line on Your Stub
Most pay stubs show Social Security and Medicare on separate lines. Both are FICA taxes, but they follow different rules. Medicare is 1.45% for employees and 1.45% for employers, with no wage cap at all.11Internal Revenue Service. 2026 Publication 926 Every dollar you earn is subject to Medicare tax.
An additional 0.9% Medicare tax applies to wages above $200,000 in a calendar year, and your employer must start withholding it once your pay with that employer crosses $200,000, regardless of filing status.12Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates Your actual liability at year-end depends on household income: married filing jointly owe the extra tax on combined wages above $250,000, and married filing separately at $125,000, so the return may show a credit or additional balance.
Add it up and the total FICA hit for most employees is 7.65% (6.2% + 1.45%) on wages up to $184,500, then 1.45% on the next slice, and 2.35% once wages pass $200,000.
The Calculation if You’re Self-Employed
There is no employer to pay the other half when you work for yourself, so you owe the full 12.4% Social Security tax plus both halves of Medicare (2.9%), for a combined self-employment tax rate of 15.3%.13Office of the Law Revision Counsel. 26 USC 1401 – Rate of Tax14Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
You do not apply that rate to your full net profit. First, multiply net earnings by 92.35% (100% minus half of 15.3%). The 12.4% Social Security portion then applies to that result, still capped at $184,500 of net earnings.15Social Security Administration. Social Security and Medicare Tax Rates The adjustment exists because employees effectively get a break through the employer’s share, and the law tries to keep self-employed workers on comparable footing.
You can also deduct the employer-equivalent portion (half of the self-employment tax you paid) when figuring adjusted gross income. That deduction reduces your income tax but not the self-employment tax itself.14Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
Workers Who Don’t Pay Social Security Tax
A few categories of workers are outside the 6.2% withholding entirely. If you fall into one of these groups, the calculation above does not apply to you.
- Students employed by the school where they are enrolled at least half-time, when the work is incidental to their studies and they are not career employees with full benefits.16Internal Revenue Service. Student FICA Exception
- Members of recognized religious groups in continuous existence since December 31, 1950 that oppose accepting insurance benefits, who apply on IRS Form 4029 and permanently waive all rights to Social Security and Medicare benefits.17IRS.gov. Form 4029, Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits
- Some state and local government employees covered by a qualifying government pension whose employer never signed a Section 218 agreement with the Social Security Administration.18Social Security Administration. Section 218 Agreements
Everyone else works from the same formula: taxable wages after any Section 125 deductions, times 6.2%, until you reach $184,500 for the year.