Yes, your W-2 does include your 401(k) contributions, just not in the place most people look first. Your elective deferrals sit in Box 12 with a letter code, not folded into the Box 1 wages figure. Code D marks traditional pre-tax contributions; Code AA marks designated Roth contributions. Whether those deferrals also reduce the taxable wages shown elsewhere on the form depends on which type you made.
Where to Find Your 401(k) on the Form
Box 12 is the reporting area for retirement deferrals. It has four slots labeled 12a through 12d, and each slot pairs a letter code with a dollar amount. Two codes apply to 401(k) plans:
- Code D covers traditional, pre-tax 401(k) deferrals. The amount is everything you contributed on a pre-tax basis during the calendar year.
- Code AA covers designated Roth 401(k) contributions. The amount is everything you contributed on an after-tax Roth basis during the year.
If you split your contributions between traditional and Roth accounts, both codes appear in Box 12 with separate amounts.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 The figures reflect your gross contributions before any investment gains or losses. Your employer totals your deferrals from every paycheck to arrive at these numbers.
Box 12 can hold up to four coded items. If you have more than four items across all Box 12 categories, your employer issues a second W-2 to capture the rest.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
How Pre-Tax Contributions Change Your Taxable Wages
Traditional 401(k) contributions shrink the federal taxable wages reported in Box 1. If you earned $85,000 in gross pay and deferred $10,000 under Code D, Box 1 should show roughly $75,000, with other pre-tax deductions like health insurance premiums also factored in. That immediate reduction in taxable income is the core benefit of a traditional 401(k).
Social Security and Medicare taxes work differently. Pre-tax 401(k) deferrals do not reduce the wages subject to FICA. Box 3 (Social Security wages) and Box 5 (Medicare wages) both include your traditional 401(k) contributions. In the example above, Boxes 3 and 5 would each reflect the full $85,000 rather than the $75,000 in Box 1. This is why Box 3 and Box 5 are usually higher than Box 1 for anyone making pre-tax retirement contributions.
Box 3 is capped at the Social Security wage base, which is $184,500 for 2026.2Social Security Administration. Contribution and Benefit Base If your total wages exceed that amount, Box 3 stops at the cap. Box 5 has no ceiling. Earnings above $200,000 are also subject to an Additional Medicare Tax of 0.9%, though your employer withholds that tax based on the $200,000 threshold regardless of your filing status. If you’re married filing jointly, the actual threshold on your return is $250,000, so any over- or under-withholding gets reconciled when you file.3Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
How Roth 401(k) Contributions Are Reported
Roth 401(k) deferrals come out of pay you’ve already been taxed on. Because of that, they don’t reduce Box 1. Your Roth contributions under Code AA are included in Box 1, Box 3, and Box 5. If your only retirement contributions are Roth and you have no other pre-tax deductions, those three boxes may show the same number.
The upfront tax break is what you give up. In exchange, qualified withdrawals in retirement come out tax-free, including investment earnings.
The Retirement Plan Checkbox in Box 13
Whenever Code D or Code AA appears in Box 12, your employer also checks the “Retirement plan” box in Box 13.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 That small checkbox has a real consequence: it can limit or eliminate your ability to deduct contributions to a traditional IRA.
When Box 13 is checked, the IRS treats you as an active participant in a workplace retirement plan, and your traditional IRA deduction starts phasing out above certain income levels. For 2026, the phase-out ranges are:
- Single or head of household: AGI between $81,000 and $91,000
- Married filing jointly, and you are the active participant: AGI between $129,000 and $149,000
- Married filing jointly, and only your spouse has the plan: AGI between $242,000 and $252,000
- Married filing separately: AGI between $0 and $10,000
Above the upper end of each range, you get no deduction at all for traditional IRA contributions.4Internal Revenue Service. 2026 Amounts Relating to Retirement Plans and IRAs, as Adjusted for Changes in Cost-of-Living – Notice 2025-67 You can still contribute to a traditional IRA, but the contribution won’t be deductible. Roth IRA contributions have their own separate income limits and aren’t affected by the Box 13 checkbox.
Employer Contributions Are Not on Your W-2
Employer matching contributions and non-elective employer contributions do not appear anywhere on your W-2. They aren’t included in Box 1, Box 3, Box 5, or Box 12. Code D and Code AA only capture your own elective deferrals.5Internal Revenue Service. Common Errors on Form W-2 Codes for Retirement Plans Employer contributions aren’t taxable to you in the year they’re made, so there’s no reason for them to show up on a wage and tax statement.
To see what your employer contributed, check your quarterly retirement account statements or your annual total compensation summary. Those documents show the full picture: your deferrals, the employer match, and investment performance.
A Note on State Taxes
Most states follow the federal treatment and exclude traditional 401(k) deferrals from state taxable wages in Box 16. A handful of states, however, treat all retirement contributions as taxable compensation at the state level. In those states, your Box 16 amount may be higher than Box 1 because the state doesn’t give you the pre-tax break on 401(k) deferrals. If your Box 16 figure looks unexpectedly high compared to Box 1, check your state’s income tax rules.
If the Numbers Look Wrong
If the 401(k) amount in Box 12 doesn’t match your own pay stubs, or if the wages in Boxes 1, 3, or 5 seem off given your contributions, start with your employer’s payroll department. Only your employer can issue a corrected W-2. The corrected version comes on Form W-2c, which shows the original incorrect figure alongside the corrected one.6Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements Your employer also files a corresponding Form W-3c with the Social Security Administration.7Social Security Administration. Helpful Hints to Forms W-2c/W-3c Filing
If you haven’t filed your return yet, wait for the W-2c and use the corrected figures on your Form 1040. If you already filed based on the incorrect W-2, you’ll need to file an amended return on Form 1040-X once you receive the corrected form. The IRS gives you three years from your original filing date (including extensions) or two years from the date you paid the tax, whichever is later, to submit the amendment.8Internal Revenue Service. Instructions for Form 1040-X
Errors in the 401(k) codes are among the more common W-2 mistakes, and they almost always change Box 1, which changes your federal income tax calculation. Wait until you have every corrected form in hand before filing the 1040-X so you only have to amend once.