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

What this line means

A continuation of Boxes 12a and 12b. If your employer reports three coded benefits, the third entry appears here. The format and codes are identical to 12a and 12b. Most employees see Box 12c used only if they have an unusually comprehensive benefits package or multiple types of retirement contributions.

Does this apply to you?

• You have three or more coded benefit types from your employer
• You contribute to a retirement plan, have employer health coverage reporting, and receive another coded benefit like HSA contributions
• Your employer uses Box 12c for an additional code that did not fit in 12a or 12b

Easy to overlook

Code W (HSA contributions) includes employer contributions If Box 12c (or any Box 12 slot) shows Code W, the amount includes both your payroll deductions and any employer contributions to your HSA. The combined total from all sources cannot exceed $4,300 (self-only) or $8,550 (family) for 2025, plus an additional $1,000 catch-up contribution if you are 55 or older. Exceeding these limits creates an excess contribution subject to a 6% excise tax each year it remains in the account. ¹ [SOURCE: IRS Publication 969 — HSA contribution limits]

Some codes require a separate tax form Certain Box 12 codes require you to file an additional form. Code W requires Form 8889 (HSA). Code AA or BB (Roth contributions) feed into your retirement plan basis tracking. Code Y or Z (Section 409A) may require reporting on Schedule 1 or Schedule 2. Ignoring these follow-up requirements generates IRS matching notices. ² [SOURCE: IRS W-2 Instructions — Box 12 code definitions]

Watch out for this

Overlooking Code W when filing Form 8889. If any Box 12 slot shows Code W, you must file Form 8889 with your return, even if you made no additional HSA contributions outside of payroll. Skipping Form 8889 causes the IRS to question whether your HSA contributions were valid, triggering a notice requesting the missing form.

Related lines on your return

• Box 12a, 12b — Form W-2 — Earlier coded benefit entries; same format and code set
• Box 12d — Form W-2 — Fourth and final coded benefit entry
• Form 8889 — HSA reporting — Required if any Box 12 slot shows Code W