W-2 Box 12 Codes and Their Meanings
| Code | What It Stands For | Explanation |
|---|---|---|
| A | Uncollected SS tax on tips | Tax owed on tips that weren’t collected from the employee |
| B | Uncollected Medicare tax on tips | Similar to A, but for Medicare |
| C | Taxable cost of group-term life insurance > $50,000 | Value of employer-paid coverage over $50,000 |
| D | Elective deferrals to a 401(k) | Includes Roth and traditional pre-tax 401(k) deferrals |
| E | Elective deferrals to 403(b) | Tax-sheltered annuities (common for schools/nonprofits) |
| F | Elective deferrals to 408(k)(6) SEP | Simplified Employee Pension plan |
| G | Elective deferrals to 457(b) | For government and certain nonprofit employees |
| H | Elective deferrals to 501(c)(18)(D) | For employees of certain nonprofit organizations |
| J | Nontaxable sick pay | Paid by a third-party (like an insurance company) |
| K | 20% excise tax on golden parachute payments | Applies to highly paid individuals |
| L | Substantiated employee business expense reimbursements | Typically used in accountable plans |
| M | Uncollected SS tax on taxable cost of group life insurance | For retirees or former employees |
| N | Uncollected Medicare tax on group-term life insurance | Same context as code M |
| P | Excludable moving expense reimbursements (for U.S. Armed Forces) | Only for active duty military moves |
| Q | Nontaxable combat pay | For military wages exempt from income tax |
| R | Archer MSA contributions | Employer contributions to Medical Savings Accounts |
| S | SIMPLE retirement plan contributions | Elective deferrals under a SIMPLE IRA |
| T | Adoption benefits | Employer-provided adoption assistance |
| V | Income from exercise of nonstatutory stock options | Compensation from stock option activity |
| W | Employer contributions to Health Savings Account (HSA) | Includes amounts employee elects via cafeteria plan |
| Y | Deferrals under 409A nonqualified deferred compensation plan | Total deferrals |
| Z | Income under section 409A | Amounts included in income under failed 409A plan |
| AA | Roth 401(k) contributions | Post-tax Roth deferrals into a 401(k) |
| BB | Roth 403(b) contributions | Post-tax Roth deferrals into a 403(b) |
| DD | Cost of employer-sponsored health coverage | Reported for informational purposes only (not taxable) |
| EE | Roth 457(b) contributions | Post-tax contributions to a 457(b) plan |
| FF | Permitted benefits under QSEHRA | Small employer health reimbursement arrangements |
| GG | Income from qualified equity grants under Sec. 83(i) | Applies to certain stock-based compensation plans |
| HH | Deferrals under Sec. 83(i) elections | Related to qualified equity grants |
Each code goes in its own 12a–12d line. You may report up to four codes (12a–12d). If more are needed, additional W-2s are issued with “Corrected” box unchecked. Do not combine codes, even if the same type (e.g., Roth and traditional deferrals).