Yes, your W-2 does include your 401(k) contributions, but not inside the main wages number in Box 1. Your elective deferrals are broken out separately in Box 12 with a letter code that tells the IRS what kind of contribution you made. Whether those deferrals also reduce the taxable wages reported elsewhere on the form depends on whether you contributed on a traditional (pre-tax) or Roth (after-tax) basis.
Where 401(k) Contributions Appear on the W-2
Box 12 is the reporting area for retirement deferrals. It has four slots labeled 12a through 12d, and each slot holds a letter code paired with a dollar amount. Two codes matter for a 401(k):
- 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, both codes appear in Box 12 with separate dollar amounts. The figures reflect your gross deferrals for the year before any investment gains or losses; your employer totals them across every paycheck to reach the Box 12 amount. Box 12 can hold up to four coded items on a single form, and if you have more, your employer issues a second W-2 to fit the rest.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3
For 2026, the elective deferral limit is $24,500, so that’s the maximum standard contribution you should see reported.2Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 Catch-up contributions for older workers are rolled into the same Code D or Code AA total.
How Traditional 401(k) Deferrals Change Box 1
Traditional 401(k) contributions shrink the federal taxable wages 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, adjusted further for any other pre-tax deductions like health insurance. That immediate reduction in taxable income is the whole point of a pre-tax deferral.
Social Security and Medicare are a different story. Pre-tax 401(k) contributions do not reduce the wages subject to FICA. Box 3 (Social Security wages) and Box 5 (Medicare wages) both include your traditional deferrals. In the example above, Boxes 3 and 5 would still reflect the full $85,000. That’s why Box 3 and Box 5 typically run 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 2026.3Social Security Administration. Contribution and Benefit Base Wages above that cap don’t show up in Box 3. Box 5 has no ceiling. Earnings above $200,000 are also subject to an Additional Medicare Tax of 0.9%, which your employer withholds using that $200,000 threshold regardless of your filing status. If you’re married filing jointly, the actual threshold on your return is $250,000, so you reconcile any over- or under-withholding when you file.4Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
How Roth 401(k) Deferrals Show Up Differently
Roth 401(k) contributions are made with money you’ve already paid income tax on. Because of that, they do not reduce Box 1. Roth deferrals 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 tradeoff is on the back end. Qualified Roth withdrawals in retirement come out tax-free, including investment earnings, so you skip the upfront tax break in exchange for tax-free growth later.
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 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 phases 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, you’re the active participant: AGI between $129,000 and $149,000
- Married filing jointly, only your spouse has the plan: AGI between $242,000 and $252,000
- Married filing separately: AGI between $0 and $10,000
Above the top of each range, you get no deduction for traditional IRA contributions.5Internal 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; the contribution just isn’t deductible. Roth IRA contributions have their own separate income limits and aren’t affected by the Box 13 checkbox.
Employer Matching Contributions Are Not on Your W-2
Employer matching and non-elective employer contributions do not appear anywhere on your W-2. They aren’t in Box 1, Box 3, Box 5, or Box 12. Code D and Code AA capture only your own elective deferrals.6Internal 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 appear on a wage and tax statement. To see what your employer put in, check your quarterly plan statements or your annual total compensation summary.
One boundary worth flagging: 457(b) deferred compensation plans use Box 12 Code G, which captures both employee deferrals and employer contributions.1Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 That rule is specific to 457(b) plans and doesn’t apply to a standard 401(k).
State Wages May Not Match
Most states follow the federal treatment and exclude traditional 401(k) deferrals from state taxable wages in Box 16. A handful of states treat all retirement contributions as taxable compensation at the state level. In those states, Box 16 may be higher than Box 1 because the state doesn’t extend the pre-tax break to 401(k) deferrals. If your Box 16 figure looks unexpectedly high compared with Box 1, check your state’s income tax rules.
What to Do If the Box 12 Amount Looks Wrong
If the 401(k) figure in Box 12 doesn’t match your own records, or if Boxes 1, 3, or 5 look off given what you contributed, 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 next to the corrected one.7Internal Revenue Service. About Form W-2 C, Corrected Wage and Tax Statements Your employer also files a matching Form W-3c with the Social Security Administration.8Social Security Administration. Helpful Hints to Forms W-2c/W-3c Filing
If you haven’t filed yet, wait for the W-2c and use the corrected figures on your Form 1040. If you already filed based on the wrong W-2, you’ll need to submit an amended return on Form 1040-X once the corrected form arrives. 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 file the amendment.9Internal Revenue Service. Instructions for Form 1040-X Errors in the 401(k) codes almost always change Box 1, which changes your federal tax, so wait until every corrected form is in hand before amending.