The W2 Box 12 codes are:
A — Uncollected Social Security or RRTA tax on tips. Include this tax on Form 1040 Schedule 4 line 58.
B — Uncollected Medicare tax on tips. Include this tax on Form 1040 Schedule 4 line 58.
C — Taxable costs of group-term life insurance over $50,000 (included in W-2 boxes 1,3 (up to Social Security wages base), and box 5.
D — Elective deferral under a 401(k) cash or arrangement plan. This includes 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 non-elective 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, not included in W-2 boxes 1, 3, or 5).
K — 20% excise tax on excess golden parachute payments.
L — Substantiated employee business expense reimbursements (nontaxable).
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 (former employees only).
P — Excludable moving expense reimbursements paid directly to a member of the U.S. Armed Forces. (not included in Boxes 1, 3, or 5)
Q — Nontaxable combat pay. See the instructions for Form 1040 or Form 1040A for details on reporting this amount.
R — Employer contributions to your Archer medical savings account (MSA). Report on Form 8853:, Archer MSAs and Long-Term Care Insurance Contracts.
S — Employee salary reduction contributions under a Section 408(p) SIMPLE. (Not included in Box 1).
T — Adoption benefits (not included in Box 1). Complete Form 8839:, Qualified Adoption Expenses, to compute any taxable and nontaxable amounts.
V — Income from exercise of non-statutory stock option(s) (included in Boxes 1, 3 (up to Social Security wage base), and 5). See Publication 525, Taxable and Nontaxable Income, for reporting requirements.
W — Employer contributions (including amounts the employee elected to contribute using a Section 125 cafeteria plan) to your health savings account (HSA).
Y — Deferrals under a Section 409A nonqualified deferred compensation plan.
Z — Income under a nonqualified deferred compensation plan that fails to satisfy Section 409A. This amount is also included in Box 1 and is subject to an additional 20% tax plus interest. See Form 1040 instructions for more information.
AA — Designated Roth contribution under a 401(k) plan.
BB — Designated Roth contributions under a 403(b) plan.
CC — For employer use only.
DD — Cost of employer-sponsored health coverage.
EE — Designated Roth contributions under a governmental 457(b) plan. This amount doesn’t apply to contributions under a tax-exempt organization 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.