Social Security wages are higher than the wages on your W-2 used for federal income tax because some paycheck deductions—most often traditional 401(k), 403(b), or 457(b) contributions—come out of your pay before income tax is calculated but stay in your pay for Social Security and Medicare tax purposes. The dollars you defer into a traditional retirement plan disappear from Box 1 and remain in Box 3. A few other items, like employer adoption assistance, work the same way. Everything else that looks unusual on the form usually traces back to one of these rules or to the Social Security wage cap.
Traditional Retirement Contributions Are the Usual Reason
If you contribute to a 401(k), 403(b), or 457(b) plan through payroll deductions, that money is subtracted from your pay before your employer calculates federal income tax withholding. It does not appear in Box 1. But it does appear in Box 3 (Social Security wages) and Box 5 (Medicare wages), because the Federal Insurance Contributions Act keeps those deferrals in the FICA wage base.1Internal Revenue Service. Are Retirement Plan Contributions Subject to Withholding for FICA, Medicare, or Federal Income Tax Your employer still withholds 6.2 percent for Social Security and 1.45 percent for Medicare on the full amount.2Social Security Administration. What Are FICA and SECA Taxes
For 2026, the elective deferral limit is $24,500, with an additional $8,000 catch-up for workers 50 and older, or $11,250 for workers ages 60 through 63.3Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 Someone who defers the full $24,500 will see Box 3 exceed Box 1 by at least that much, purely from the retirement plan. Those deferred earnings also count toward your lifetime Social Security record and factor into your future benefit.4Social Security Administration. Review Record of Earnings
Roth Contributions Do Not Create the Gap
Designated Roth 401(k) and Roth 403(b) contributions are made with after-tax dollars, so they stay in Box 1 as well as Boxes 3 and 5.1Internal Revenue Service. Are Retirement Plan Contributions Subject to Withholding for FICA, Medicare, or Federal Income Tax If you split your deferrals between traditional and Roth, only the traditional portion widens the gap between your income tax wages and your Social Security wages.
Employer Adoption Assistance
Adoption assistance paid through an employer program is the other common source of the discrepancy. For 2026, up to $17,670 of qualified adoption expenses can be excluded from your federal income tax wages, but the full benefit is still subject to Social Security and Medicare taxes and is included in Box 3.5Internal Revenue Service. Publication 15-B (2026), Employer’s Tax Guide to Fringe Benefits If you used an employer adoption benefit during the year, that alone can produce a sizable gap.
One benefit that sometimes gets blamed but should not: employer-provided group-term life insurance above $50,000. The imputed cost is added to both Box 1 and Box 3, so it raises both by the same amount and does not create a gap.6Internal Revenue Service. Group-Term Life Insurance
Pre-Tax Deductions That Reduce Both Boxes
Not every pre-tax deduction widens the gap. Contributions through a Section 125 cafeteria plan, which typically cover your share of health insurance premiums and flexible spending account elections, are excluded from both federal income tax and FICA wages.7Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans Health savings account contributions run through payroll work the same way, lowering Box 1 and Box 3 equally.5Internal Revenue Service. Publication 15-B (2026), Employer’s Tax Guide to Fringe Benefits The 2026 HSA limit is $4,400 for self-only coverage and $8,750 for family coverage.8Internal Revenue Service. Notice 26-05 – 2026 HSA Contribution Limits
So the gap only comes from deductions that are pre-tax for income tax but still taxable for FICA. Mostly, that means traditional retirement deferrals and adoption assistance.
When Box 1 Is Actually Higher Than Box 3
Social Security tax stops applying once your earnings hit the annual wage base. For 2026 that cap is $184,500.9Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet If your total pay exceeds it, Box 3 stops at $184,500 while Box 1 keeps going. High earners often see the reverse of the usual pattern, with income tax wages larger than Social Security wages.
Medicare has no wage base. Every dollar is subject to the 1.45 percent Medicare tax, and once your wages pass $200,000 your employer must withhold an additional 0.9 percent on the excess.10Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates That is why Box 5 often runs higher than Box 3 for high earners.
Checking the Math on Your Own W-2
You can usually reconcile the two numbers using Box 12. Box 12 lists specific deductions and benefits by code. Codes D, E, and G are elective deferrals to 401(k), 403(b), and 457(b) plans; Code T is employer adoption assistance.11Internal Revenue Service. General Instructions for Forms W-2 and W-3 (2026) Take your Box 1 figure, add the amounts in Box 12 for pre-tax retirement contributions (D, E, F, G, or S) and any adoption assistance (T), and the total should come out very close to Box 3, assuming your wages fall below the $184,500 cap. If you also had group-term life insurance above $50,000 (Code C), remember that it already sits in both boxes and does not need to be added back.
What to Do If It Still Does Not Add Up
If the numbers do not reconcile after accounting for retirement deferrals, adoption assistance, and the wage cap, start with your employer’s payroll department. Most gaps turn out to be explainable once someone walks you through which deductions hit which box.
If your employer will not issue a corrected W-2 by the end of February, you can call the IRS at 800-829-1040 to file a Form W-2 complaint. The IRS will contact your employer and request a corrected form within ten days. If a corrected form still does not arrive in time to file, you can use Form 4852 as a substitute W-2, basing your figures on your final pay stub for the year.12Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted If a corrected W-2 shows up later with different numbers, amend your return with Form 1040-X.