What Is Box 12C on Your W-2? Common Codes and What to Do

Box 12c on your W-2 is not a code of its own. It’s simply the third of four slots (12a, 12b, 12c, 12d) that your employer uses to report items that don’t fit in the regular wage boxes. What matters is the two-letter code printed next to the dollar amount in that slot. Your employer picks the slot arbitrarily, so a code sitting in 12c means exactly what it would mean in 12a or 12b.

To figure out what your 12c entry represents, find the letters (D, DD, W, C, and so on) and match them to the list below.

How the Four Slots Work

Box 12 holds up to four separate entries, one per slot. Each entry has a two-letter code and a dollar amount. If you have more than four items to report, your employer issues an additional W-2 to fit the extras.

The codes fall into two groups. Some flag amounts that were already excluded from your taxable wages in Box 1, like pre-tax 401(k) contributions. Others flag amounts that are included in Box 1 but need a separate line so the IRS can see what they are, like the taxable cost of employer-paid life insurance above $50,000. Either way, the code tells you and the IRS how the dollar figure should be treated.

Retirement Plan Codes

Retirement contributions are the most common reason a code lands in Box 12c.

Code D — Pre-tax elective deferrals to a 401(k), including SIMPLE 401(k) plans. Excluded from Box 1 wages, but still subject to Social Security and Medicare tax.
Code E — Pre-tax elective deferrals to a 403(b) plan (common at schools and nonprofits). Same tax treatment as Code D.
Code F — Elective deferrals to a salary reduction SEP (SARSEP) under Section 408(k)(6). No new SARSEPs have been established since 1997, but existing ones still operate.
Code G — Elective deferrals and employer contributions to a Section 457(b) deferred compensation plan.
Code H — Elective deferrals to a Section 501(c)(18)(D) tax-exempt organization plan.
Code S — Employee salary reduction contributions to a SIMPLE IRA under Section 408(p).

All of these reduce your Box 1 taxable wages by the amount reported, which is why the money doesn’t show up in your federal taxable income for the year.¹

Roth Contribution Codes

Roth contributions use after-tax dollars, so they do not reduce Box 1 wages:

Code AA — Designated Roth contributions to a 401(k).
Code BB — Designated Roth contributions to a 403(b).
Code EE — Designated Roth contributions to a governmental Section 457(b).

Roth contributions share the same annual deferral limit as their pre-tax counterparts. Combined pre-tax and Roth deferrals to the same plan type cannot exceed that limit.²

Health and Benefit Codes

Code W — HSA Contributions

Code W is the total of all contributions to your Health Savings Account made through payroll, both what your employer put in and what you contributed through a cafeteria plan. The amount is excluded from Boxes 1, 3, and 5. If you have a Code W entry, you must file Form 8889 with your return to reconcile the contributions against the annual limit. For 2026, the HSA contribution ceiling is $4,400 for self-only coverage and $8,750 for family coverage,³ with an additional $1,000 catch-up if you’re 55 or older.⁴

Code DD — Cost of Employer-Sponsored Health Coverage

Code DD reports the total cost of your employer-sponsored health plan, combining the employer’s share and your payroll-deducted share. It is informational only. It does not make your health benefits taxable and does not affect any figure on your return. Reporting is required under the Affordable Care Act so you can see the full value of the coverage.⁵

Code C — Group-Term Life Insurance Over $50,000

If your employer provides group-term life insurance above $50,000, the taxable cost of the coverage over that threshold appears as Code C. The figure is included in Boxes 1, 3, and 5, so income tax, Social Security tax, and Medicare tax all apply. The amount isn’t the premium your employer paid; it’s calculated from an IRS table based on your age and the excess coverage.⁶

Code T — Adoption Benefits

Code T reports employer-provided adoption assistance. The amount is excluded from Box 1 but may be partially or fully taxable depending on your income. File Form 8839 to calculate the taxable and excludable portions. The 2026 maximum exclusion is $17,670 per eligible child.⁷

Compensation Codes

Code V — Nonstatutory Stock Option Income

Code V is the spread between fair market value and the exercise price when you exercised nonstatutory stock options. This amount is already included in Boxes 1, 3, and 5. The separate disclosure helps track the compensation for cost basis purposes when you later sell the shares.²

Code P — Excludable Moving Expense Reimbursements

Code P covers moving expense reimbursements excluded from income. Since the Tax Cuts and Jobs Act, this exclusion applies only to active-duty members of the U.S. Armed Forces who move because of a permanent change of station. Civilian moving reimbursements are taxable and appear in Box 1 instead.²

Code Q — Nontaxable Combat Pay

Military employers use Code Q for nontaxable combat pay. The income is excluded from federal tax by default, but you can elect to include it as earned income when calculating the Earned Income Tax Credit. Depending on your numbers, that election can raise your EITC. It’s worth running both ways.⁸

Code L — Substantiated Business Expense Reimbursements

Code L reports reimbursements paid to you under an accountable plan for business expenses you documented. Because you provided substantiation and returned any excess, the amounts are not taxable and are excluded from Box 1.²

Codes Y and Z — Section 409A Deferred Compensation

These codes work as a pair. Code Y reports deferrals under a Section 409A nonqualified deferred compensation plan and is informational; it does not add to Box 1. Code Z is different: it reports income from a nonqualified plan that failed Section 409A. That income is included in Box 1 and carries an additional 20% penalty tax on top of regular income tax. A Code Z entry usually warrants professional help preparing your return.²

Less Common Codes You Might See

Codes A and B report uncollected Social Security and Medicare tax on tips when your tip income was too high for your employer to withhold in full. You’ll owe those amounts directly on your return. Codes M and N are the same idea for former employees with group-term life insurance over $50,000. Code R covers employer contributions to an Archer MSA. Code FF reports permitted benefits under a qualified small employer health reimbursement arrangement (QSEHRA). Codes GG and HH relate to qualified equity grants under Section 83(i), which let certain startup employees defer income on stock received from their employer.²

What You Actually Need to Do With Your Box 12c Entry

Most Box 12 codes are informational. The amounts are already reflected in Box 1 (or intentionally excluded from it), and you don’t need to enter them anywhere on Form 1040 directly. Tax software will prompt you to type in the code and amount, and it routes everything from there. Paper filers generally don’t have to transfer Box 12 amounts to specific lines on the return.

A few codes do require follow-up:

Code W triggers Form 8889 for HSA reconciliation. Skipping it is a common source of IRS notices.
Code T triggers Form 8839 to determine the taxable portion of adoption benefits.
Codes A, B, M, and N mean you owe uncollected Social Security or Medicare tax on your return.
Code Z carries the 20% Section 409A penalty tax on top of regular income tax.

If you contribute to retirement plans through more than one employer, add up your Code D (or E, G, S, AA, BB, EE) amounts across all your W-2s. Combined deferrals over the annual limit have to be corrected by April 15 of the following year through a distribution of the excess plus earnings. That deadline does not extend if you file an extension, and missing it results in the excess being taxed twice: once in the contribution year and again when the money leaves the plan.⁹

If the Code or Amount Looks Wrong

Start with your employer’s payroll department. Compare the Box 12 figure to your final pay stubs for the year. If something is off, ask for a corrected W-2c.

If payroll won’t fix it or you can’t reach them, wait until after the end of February, then call the IRS at 800-829-1040 or go to a Taxpayer Assistance Center. The IRS will contact your employer and ask for a corrected W-2 within ten days, and will send you Form 4852 as a substitute.¹⁰

If a corrected form still hasn’t arrived by the filing deadline, use Form 4852 with your best estimates from your pay records and explain the steps you took to obtain the correct W-2. If a corrected W-2 later shows different numbers, file Form 1040-X to amend.¹¹

1
Internal Revenue Service. Common Errors on Form W-2 Codes for Retirement Plans
2
Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 – Box 12 Codes
3
Internal Revenue Service. Expanded Availability of Health Savings Accounts Under the One, Big, Beautiful Bill Act
4
Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans
5
Internal Revenue Service. Form W-2 Reporting of Employer-Sponsored Health Coverage
6
Office of the Law Revision Counsel. 26 USC 79 – Group-Term Life Insurance Purchased for Employees
7
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
8
Internal Revenue Service. Military and Clergy Rules for the Earned Income Tax Credit
9
Internal Revenue Service. Consequences to a Participant Who Makes Excess Deferrals to a 401(k) Plan
10
Internal Revenue Service. W-2 – Additional, Incorrect, Lost, Non-Receipt, Omitted
11
Internal Revenue Service. Substitute for Form W-2, Wage and Tax Statement