Where Is FICA on Your W-2? Boxes 3–6 and Common Issues

On your W-2, FICA is split across four boxes. Boxes 3 and 4 handle Social Security: Box 3 is the wages subject to the tax, Box 4 is the tax withheld. Boxes 5 and 6 handle Medicare the same way: Box 5 is the wages, Box 6 is the tax. If you earned tips, Box 7 reports the Social Security portion of those tips. For 2026, the most Social Security tax a single employer should show in Box 4 is $11,439, which is 6.2% of the $184,500 wage cap.¹

Boxes 3 and 4: Social Security

Box 3 shows the wages your employer paid you that were subject to Social Security tax. The figure stops at the annual wage base, $184,500 for 2026. Earn $300,000 and Box 3 still caps there.² The Social Security Administration uses this number to calculate your future retirement and disability benefits.

Box 4 is the actual Social Security tax withheld. The employee rate is 6.2%, and your employer matches it with another 6.2%, though only your share lands on the W-2.³ For 2026, Box 4 should not exceed $11,439 from any one employer.²

If you work in a tipped job, Box 7 reports Social Security tips you declared to your employer. Box 7 sits apart from Box 3, but the two together still cannot cross the $184,500 ceiling.²

Boxes 5 and 6: Medicare

Box 5 is the wages subject to Medicare tax. Medicare has no wage cap, so Box 5 usually matches or exceeds Box 3.⁴ For high earners the gap can be large, because every dollar still counts for Medicare after Social Security has stopped at $184,500.

Box 6 is the Medicare tax withheld. The standard employee rate is 1.45%, matched by your employer for a combined 2.9%.³

Box 6 can also include the Additional Medicare Tax, a 0.9% surcharge your employer must begin withholding once your wages pass $200,000 in a calendar year.⁵ That $200,000 withholding trigger ignores filing status. The threshold at which you actually owe the tax on your return does not: $250,000 for married filing jointly, $200,000 for single or head of household, $125,000 for married filing separately.⁶ If you file separately, you can owe this tax on wages above $125,000 even when nothing extra was withheld, and you square it up when you file.

Why Boxes 3 and 5 Don’t Match Box 1

Most people notice their federal taxable wages in Box 1 come in lower than Boxes 3 and 5. That is usually correct. The three boxes measure different things.

The common reason FICA wages run higher is a retirement plan contribution. Money you defer into a 401(k), 403(b), or similar plan is pulled out of Box 1 because it isn’t subject to federal income tax, but it stays in Boxes 3 and 5 because Social Security and Medicare tax still apply.²

Health insurance premiums and HSA contributions routed through a Section 125 cafeteria plan behave differently. They come out of all three boxes, because the cafeteria-plan route is exempt from income tax and FICA alike.⁷ Direct HSA contributions made outside an employer plan don’t get the FICA break.⁸

Employer-provided group-term life insurance can push Boxes 3 and 5 above what you took home. Coverage over $50,000 generates a taxable cost on the excess that gets added to Boxes 1, 3, and 5, and shown in Box 12 with Code C.² That amount never hit your paycheck, but it counts as FICA wages.

When the FICA Numbers Look Wrong

Multiply Box 3 by 6.2% or Box 5 by 1.45% and your answer may miss Box 4 or Box 6 by a few cents. Employers calculate withholding each pay period and round to the nearest cent, so small rounding differences add up over the year. The IRS calls these fractions-of-cents adjustments, and they’re expected.⁷ A dollar or less of discrepancy almost always comes from this.

A real error is a different problem. If a benefit was coded wrong, a bonus taxed under the wrong rules, or a payroll system misfired, ask your employer’s payroll department to issue a corrected W-2, called a W-2c.⁹

If a single employer withheld more Social Security tax than the $11,439 maximum, you cannot fix that on your return. The employer has to refund the excess, and if they refuse, you file Form 843 with copies of your W-2. A different rule applies when you worked for two or more employers and their combined Box 3 amounts pushed you past $184,500. Each employer withheld on its own, so your total Box 4 figures can exceed $11,439. In that case, add up the Box 4 amounts from every W-2, subtract $11,439, and claim the difference as a credit on Schedule 3 of Form 1040.¹⁰

When Boxes 3 Through 6 Show Zero

A few workers are legally outside FICA, and their W-2s reflect that with zeros or reduced amounts in these boxes.

Students employed by the school they attend may be exempt. The job must be incidental to your studies, and you can’t be classified as a professional employee, meaning you generally aren’t eligible for retirement contributions, vacation, or similar benefits through the role.¹¹
Nonresident alien students and scholars on F-1, J-1, or M-1 visas are generally exempt from FICA on authorized work for their first five calendar years in the U.S. The exemption ends when they become resident aliens or change to a non-exempt status.¹²
Members of a recognized religious group that has existed continuously since December 31, 1950, and that conscientiously opposes public and private insurance benefits, can apply for exemption using Form 4029. Approval also waives the member’s right to Social Security and Medicare benefits.¹³

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), Employers Tax Guide
8
Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans
9
Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements
10
Internal Revenue Service. Topic No. 608, Excess Social Security and RRTA Tax Withheld
11
Internal Revenue Service. Student FICA Exception
12
Internal Revenue Service. Foreign Student Liability for Social Security and Medicare Taxes
13
Internal Revenue Service. Form 4029, Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits