W-2 Box 12 Codes Explained - What Every Letter Means (2026)
Box 12 contains letter codes that explain retirement contributions, taxable benefits, and certain corrections. The meaning of the letter determines whether the value reduces your taxable wages or is only informational.
Key Findings
- D, E, G, W, and similar pre-tax items often reduce Box 1.
- Roth codes usually stay inside Box 1 because they are after-tax.
- DD is informational and does not change taxable wages.
Common Box 12 codes
| Code | Meaning | Tax implication |
|---|---|---|
| A | Uncollected SS tax on tips | Add to Schedule 2 |
| B | Uncollected Medicare on tips | Add to Schedule 2 |
| C | Taxable cost of group-term life over $50K | Already in Box 1 |
| D | Traditional 401(k) elective deferrals | Reduces Box 1 |
| E | 403(b) deferrals | Reduces Box 1 |
| G | 457(b) deferrals | Reduces Box 1 |
| W | Employer HSA contributions | Not in Box 1 |
| AA | Roth 401(k) contributions | Already in Box 1 |
| BB | Roth 403(b) contributions | Already in Box 1 |
| DD | Employer-sponsored health coverage | Informational only |
| EE | Roth 457(b) contributions | Already in Box 1 |
| FF | Qualified small employer HRA | Health reimbursement |
Verify contribution limits against current IRS guidance or the 2026 data files before acting on any code amount.