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W2 Form

What each box on your W-2 means, why your wages differ between Box 1, 3 and 5, common Box 12 codes, and a calculator that works out your boxes from your pay.

Updated November 4, 2026. Free, no sign-up; everything runs in your browser and nothing you type is stored.

W2 form box calculator (2026)

Gross pay for the year ($)Pre-tax 401(k) / 403(b) ($, Box 12 D or E)Pre-tax health premiums and payroll HSA ($, Section 125)

Box 1: wages subject to income tax

–

–Box 3: Social Security wages

–Box 4: Social Security tax

–Box 5: Medicare wages

–Box 6: Medicare tax

Why Box 1 is lower than Box 3 and Box 5

Your W-2 shows three different wage totals. Box 1 (federal income tax wages) excludes pre-tax 401(k) or 403(b) deferrals and Section 125 health premiums. Box 3 (Social Security wages) and Box 5 (Medicare wages) still include 401(k) deferrals, because those are subject to FICA, but exclude Section 125 health premiums and HSA contributions made through payroll. Box 3 stops at the 2026 wage base of $184,500, so Box 4 can't exceed $11,439 (6.2%). Box 6 is 1.45% of Box 5, plus 0.9% Additional Medicare tax your employer withholds on wages over $200,000.

Example: $80,000 of pay, $8,000 of 401(k) and $3,000 of health premiums: Box 1 $69,000, Boxes 3 and 5 $77,000.

Common Box 12 codes

D: 401(k) elective deferrals. E: 403(b). G: 457(b). AA: Roth 401(k). BB: Roth 403(b).
W: employer and payroll HSA contributions. DD: cost of employer health coverage (informational, not taxable).
C: taxable group-term life over $50,000. P: excludable moving reimbursements (military).

Employers must send W-2s by January 31. If yours is wrong, ask for a corrected W-2c. Check your take-home with the bring home pay calculator.

Common questions

Why is Box 1 lower than Box 3 on my W-2?

Pre-tax 401(k) or 403(b) deferrals reduce Box 1 but not Box 3 or Box 5.

What is the maximum Social Security tax on a W-2 for 2026?

$11,439 (6.2% of the $184,500 wage base).

What does Box 12 code D mean?

Elective deferrals to a 401(k) plan.

Sources

More paycheck and tax calculators: Tax Extension (Form 4868) · UI Claims · W8BEN Form · 1099 Estimated Tax Calculator

General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.