12b — Box 12b Codes Updated for tax year 2025

What this line means

A continuation of Box 12a. If your employer needs to report more than one coded benefit, the second entry goes here. The format is the same: a letter code followed by a dollar amount. Box 12b uses the same set of codes as Box 12a — the box number does not change the meaning of the code.

Does this apply to you?

• You have more than one type of coded compensation or benefit reported by your employer
• You contributed to a retirement plan and also received employer-paid health coverage (two separate codes)
• You have both a traditional 401(k) and a Roth 401(k) — each gets its own code and line in Box 12

Easy to overlook

The order of codes across 12a-12d does not matter Employers can list codes in any order across the four Box 12 slots. Code D (401(k)) might appear in 12a for one employer and 12c for another. The code itself determines what the amount represents, not which sub-box it appears in. When comparing W-2s from different employers, focus on the letter codes, not the box positions. ¹ [SOURCE: IRS W-2 Instructions — Box 12 code definitions]

Code C amounts are already in Box 1 If Box 12b (or any Box 12 slot) shows Code C — the taxable cost of group-term life insurance over $50,000 — that amount is already included in your Box 1 wages. This catches filers off guard because they did not receive the money as cash, but the IRS treats the imputed value of excess life insurance as taxable compensation. ² [SOURCE: IRS Publication 525 — Taxable and Nontaxable Income]

Watch out for this

Manually adding Box 12b amounts to your income on your tax return. Tax software reads the codes and handles them correctly. Filers who manually enter W-2 data sometimes enter Box 12 amounts as “other income” in addition to Box 1, creating a duplicate. Each Box 12 code has specific tax treatment — some reduce income, some are informational, and most are already reflected in Box 1.

Related lines on your return

• Box 12a — Form W-2 — First coded benefit entry; same format and code set as Box 12b
• Box 12c, 12d — Form W-2 — Third and fourth coded benefit entries if needed
• Box 1 — Form W-2 — The net result after all pre-tax deductions and taxable additions from Box 12 codes