Social Security Taxes and FICA: What Workers and Employers Pay
The Federal Insurance Contributions Act (FICA) establishes the payroll tax mechanism that funds Social Security and Medicare, imposing mandatory contributions on both wage earners and their employers. Understanding how these rates are structured, how the taxable wage base operates, and where self-employed individuals fit into the system is essential for payroll compliance and retirement planning. This page covers FICA rates, the Social Security wage base, employer and employee obligations, and the boundaries that determine who pays what.
Definition and scope
FICA is codified under 26 U.S.C. §§ 3101–3128 and imposes two distinct taxes: the Old-Age, Survivors, and Disability Insurance (OASDI) tax — commonly called the Social Security tax — and the Hospital Insurance (HI) tax for Medicare. Together, these taxes fund the benefit programs administered by the Social Security Administration (SSA) and, through Medicare, by the Centers for Medicare & Medicaid Services (CMS).
The Social Security portion of FICA applies at a combined rate of 12.4%, split equally between employee and employer at 6.2% each (IRS Publication 15, Circular E). The Medicare portion adds another 2.9% combined, split equally at 1.45% each. Taken together, the total FICA obligation per employee is 15.3% of covered wages, with the employer and employee each bearing 7.65%.
A defining structural feature of the Social Security tax is the annual wage base cap. For 2024, the SSA set the taxable maximum at $168,600, meaning wages above that threshold are not subject to the 6.2% Social Security portion. The Medicare tax carries no wage cap; however, wages above $200,000 per year for individual filers are subject to an Additional Medicare Tax of 0.9% under 26 U.S.C. § 3101(b)(2), which is the employee's sole obligation — employers do not match this additional levy.
FICA taxes connect directly to a worker's eligibility for future benefits. The SSA uses covered earnings to calculate Social Security credits, which determine whether a worker qualifies for retirement, disability, or survivors benefits.
How it works
Every pay period, employers withhold the employee's share of FICA from gross wages and simultaneously incur their own matching contribution. The employer then remits both shares to the IRS on a deposit schedule determined by total tax liability — either monthly or semi-weekly, per IRS Publication 15.
The mechanics operate as follows:
- Gross wages calculated — the employer determines the employee's total compensation for the pay period, including salaries, hourly wages, bonuses, and most other cash compensation.
- Wage base check — year-to-date earnings are compared against the annual Social Security taxable maximum. Once cumulative wages cross $168,600 (2024), Social Security withholding stops for the remainder of that calendar year.
- Employee withholding computed — 6.2% of wages up to the cap for Social Security; 1.45% of all wages for Medicare; 0.9% additional on wages exceeding $200,000.
- Employer match computed — the employer calculates its own 6.2% + 1.45% match on the same wage amounts (but does not match the 0.9% additional Medicare tax).
- Deposit and reporting — combined amounts are deposited with the IRS; Form 941 (Employer's Quarterly Federal Tax Return) reports total withholding and deposits for reconciliation.
The earnings recorded each year form the average indexed monthly earnings (AIME) calculation that the SSA later uses to determine a worker's primary insurance amount (PIA).
Common scenarios
Standard W-2 employment — The most common scenario. An employee earning $60,000 in 2024 has $3,720 withheld for Social Security (6.2% × $60,000) and $870 withheld for Medicare (1.45% × $60,000), with the employer matching each figure identically.
High-wage earner crossing the wage base — An employee earning $200,000 in 2024 pays Social Security tax only on the first $168,600, capping that liability at $10,453.20. On the full $200,000, Medicare tax totals $2,900 (1.45%). No additional Medicare tax applies at $200,000 exactly; the 0.9% surcharge activates only on wages above that threshold.
Self-employed workers — A self-employed individual legally occupies both the employer and employee roles. Under the Self-Employment Contributions Act (SECA), the combined rate is 15.3% on net self-employment income up to the wage base. The IRS allows a deduction of one-half of self-employment tax from gross income (IRS Schedule SE), partially offsetting the double burden. This topic is covered in detail at Social Security for Self-Employed.
Tipped employees — Tips count as FICA-covered wages. Employees must report cash tips to their employer, who then withholds FICA on reported tip income per IRS Revenue Ruling 59-252.
Decision boundaries
Several structural distinctions govern whether FICA applies, at what rate, and to whom:
Employee vs. independent contractor — FICA applies only to employees. Workers classified as independent contractors are subject to SECA rather than FICA, with no employer matching. Misclassification is a documented IRS enforcement priority; the IRS 20-factor test governs classification determinations.
Exempt employment categories — Certain classes of workers are wholly or partially exempt from FICA. Student workers employed by the institution where they are enrolled may qualify for a FICA exemption under 26 U.S.C. § 3121(b)(10). Some state and local government employees covered by public pension plans in lieu of Social Security are also exempt; the Government Pension Offset rule can affect their eventual Social Security benefits.
Foreign workers — Nonresident aliens on certain visa categories (F-1, J-1, M-1, Q-1) are exempt from FICA withholding on wages earned in that visa status, per IRS Publication 515. Coverage rules for workers employed abroad by US companies vary by totalization agreement.
Totalization agreements — The SSA has active totalization agreements with 30 countries (SSA Office of International Programs) to prevent dual taxation of workers who would otherwise owe contributions to two national systems simultaneously. A US worker assigned abroad for fewer than 5 years typically remains covered only under the US system.
Understanding FICA obligations is one component of the broader Social Security funding structure, which also includes trust fund mechanics and projected solvency timelines. Workers seeking a comprehensive overview of how all Social Security program types interconnect can consult the program overview at the site index.