Box 12 on your W-2 form reports several different types of compensation and benefits. If applicable, this box will indicate a single or double letter code followed by a dollar amount. Here’s what those codes mean:
| Box 12 code | Meaning |
| A | Uncollected Social Security or RRTA tax on tips |
| B | Uncollected Medicare tax on tips (but not Additional Medicare Tax) |
| C | Taxable cost of group-term life insurance over $50,000 (included in your wages in boxes 1, 3, and 5) |
| D | Elective deferrals to a section 401(k) cash or deferred arrangement plan, including a SIMPLE 401(k) arrangement |
| E | Elective deferrals under a section 403(b) salary reduction agreement |
| F | Elective deferrals under a section 408(k)(6) salary reduction SEP |
| G | Elective deferrals and employer contributions (including nonelective deferrals) to a section 457(b) deferred compensation plan |
| H | Elective deferrals to a section 501(c)(18)(D) tax-exempt organization plan |
| J | Nontaxable sick pay (information only) |
| K | 20% excise tax on excess golden parachute payments |
| L | Substantiated employee business expense reimbursements |
| M | Uncollected Social Security or RRTA tax on taxable cost of group-term life insurance over $50,000 (former employees only) |
| N | Uncollected Medicare tax on taxable cost of group-term life insurance over $50,000 (but not Additional Medicare Tax — former employees only) |
| P | Excludable moving expense reimbursements paid directly to a member of the U.S. Armed Forces for military orders |
| Q | Nontaxable combat pay |
| R | Employer contributions to an Archer MSA |
| S | Employee salary reduction contributions under a section 408(p) SIMPLE plan |
| T | Adoption benefits |
| V | Income from exercise of non-statutory stock option(s) |
| W | Employer contributions (including employee contributions through a cafeteria plan) to an employee’s health savings account (HSA) |
| Y | Deferrals under a section 409A non-qualified deferred compensation plan |
| Z | Income under a non-qualified deferred compensation plan that fails to satisfy section 409A |
| AA | Designated Roth contributions under a section 401(k) plan |
| BB | Designated Roth contributions under a section 403(b) plan |
| DD | Cost of employer-sponsored health coverage |
| EE | Designated Roth contributions under a governmental section 457(b) plan |
| FF | Permitted benefits under a qualified small employer health reimbursement arrangement |
| GG | Income from qualified equity grants under section 83(i) |
| HH | Aggregate deferrals under section 83(i) elections as of the close of the calendar year |