Where Is FICA on Your W-2? Social Security and Medicare in Boxes 3–6

On your W-2, FICA is split across four boxes: Boxes 3 and 4 cover Social Security, and Boxes 5 and 6 cover Medicare. Box 3 is the wages subject to Social Security tax; Box 4 is the Social Security tax your employer withheld. Box 5 is the wages subject to Medicare tax; Box 6 is the Medicare tax withheld. For 2026, the most Social Security tax you should see in Box 4 from a single employer is $11,439, calculated from the wage cap of $184,500.¹

Boxes 3 and 4: Social Security

Box 3 shows the wages your employer paid you that were subject to Social Security tax, capped at the annual wage base. For 2026 that cap is $184,500, so even if you earned $300,000, Box 3 will stop at $184,500.² The Social Security Administration uses this figure to calculate your future retirement and disability benefits.

Box 4 is the actual dollar amount withheld. The employee rate is 6.2%, and your employer pays a matching 6.2% that never appears on your W-2.³ So the ceiling in Box 4 for 2026 is $184,500 × 6.2% = $11,439. Anything higher than that from one employer signals an error.²

Tipped workers may also see an amount in Box 7 for Social Security tips they reported. Box 7 sits alongside Box 3, but Box 3 and Box 7 combined still can’t exceed the $184,500 wage base.²

Boxes 5 and 6: Medicare

Box 5 is the wages subject to Medicare tax. Medicare has no annual wage cap, so Box 5 will equal or exceed Box 3 for most workers, and high earners will often see it well above Box 3.⁴

Box 6 shows the Medicare tax your employer withheld. The standard employee rate is 1.45%, with employers matching another 1.45% for a combined 2.9%.³

Box 6 may also include the Additional Medicare Tax, a 0.9% surcharge your employer must start withholding once your wages pass $200,000 in a calendar year.⁵ That $200,000 trigger applies to employer withholding regardless of your filing status. The threshold at which you actually owe the tax on your return is different: $250,000 for married filing jointly, $200,000 for single or head of household, and $125,000 for married filing separately.⁶ The gap catches people. If you’re married filing separately, you could owe Additional Medicare Tax on wages above $125,000 even though your employer didn’t start withholding until $200,000. You settle the difference when you file.

Why Boxes 3 and 5 Don’t Match Box 1

Most people notice Box 1 (federal taxable wages) is lower than Boxes 3 and 5. That isn’t a mistake. The boxes measure different things, and some pre-tax deductions reduce one but not the others.

The usual reason Boxes 3 and 5 run higher than Box 1 is retirement plan contributions. If you defer part of your salary into a 401(k), 403(b), or similar plan, that money is removed from Box 1 because it isn’t currently subject to federal income tax. But it stays in Boxes 3 and 5, because it’s still subject to Social Security and Medicare.²

Not every pre-tax benefit works that way. Health insurance premiums and HSA contributions made through a Section 125 cafeteria plan reduce all three boxes equally, because they’re exempt from both income tax and FICA.⁷ Direct HSA contributions you make outside an employer plan don’t get the FICA break; only the cafeteria-plan route does.⁸

Employer-provided group-term life insurance over $50,000 can push Boxes 3 and 5 up too. The taxable cost of the excess coverage gets added to Boxes 1, 3, and 5, and appears in Box 12 with Code C.² You never saw the money in your paycheck, but it still counts as FICA wages.

If You Had Two Employers and Paid Too Much Social Security Tax

Each employer withholds Social Security tax independently, so if you worked for two or more employers in the same year and your combined wages exceeded $184,500, more than $11,439 total may have come out of your paychecks. You can claim the excess as a credit on your federal return.⁹ Add up the Box 4 amounts from each W-2, subtract $11,439 for 2026, and enter the difference on Schedule 3 of Form 1040.

The rule flips if a single employer over-withheld. You can’t claim that on your return. Ask the employer to correct the mistake and refund the excess. If they refuse, file Form 843 (Claim for Refund) with copies of your W-2 attached.⁹

If the FICA Numbers on Your W-2 Look Wrong

Check the math first. Employers calculate withholding per pay period, and rounding each period to the nearest cent can produce a total that’s off by a few cents from what you’d get by multiplying Box 3 by 6.2%. The IRS calls these fractions-of-cents adjustments, and they’re normal.⁷ A discrepancy of a dollar or less almost always falls into this category.

If the gap is real, contact your employer’s payroll department. Errors in Boxes 3 through 6 happen for mundane reasons: the wrong tax code applied to a bonus, a benefits deduction classified incorrectly, a system glitch during a payroll migration. If payroll agrees, they’ll issue a corrected form called a W-2c.¹⁰

If your employer won’t cooperate and you still don’t have a corrected form by the end of February, call the IRS at 800-829-1040 or visit a Taxpayer Assistance Center to file a W-2 complaint. The IRS will send your employer a letter requesting a corrected W-2 within ten days. If a corrected form doesn’t arrive in time to file, you can use Form 4852 as a substitute, estimating your wages and withholdings from your final pay stub.¹¹

When Boxes 3–6 Are Legitimately Empty

Most wage earners have no choice about FICA. A few groups are legally exempt, and their W-2s will show zeros or reduced amounts in Boxes 3 through 6.

Students working at their own school. If you’re enrolled and regularly attending classes at a college or university and you work for that same institution, your wages may be exempt from FICA. The job has to be incidental to your studies, and you can’t be classified as a professional employee (generally meaning you aren’t eligible for retirement contributions, vacation, or similar benefits through the job).¹²
Nonresident alien students and scholars. Foreign nationals in F-1, J-1, or M-1 status who have been in the U.S. for fewer than five calendar years are generally exempt from FICA on wages for work authorized under their visa. The exemption ends once they become resident aliens or switch to a non-exempt immigration status.¹³
Members of qualifying religious groups. If you belong to a recognized religious group that has existed continuously since December 31, 1950, and that group conscientiously opposes private and public insurance benefits, you can apply for exemption using Form 4029. Approval means you also waive your right to Social Security and Medicare benefits.¹⁴

1
Social Security Administration. Contribution and Benefit Base
2
Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
3
Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
4
Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026)
5
Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
6
Internal Revenue Service. Topic No. 560, Additional Medicare Tax
7
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
8
Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans
9
Internal Revenue Service. Topic No. 608, Excess Social Security and RRTA Tax Withheld
10
Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements
11
Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted
12
Internal Revenue Service. Student FICA Exception
13
Internal Revenue Service. Foreign Student Liability for Social Security and Medicare Taxes
14
Internal Revenue Service. Form 4029, Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits