Below is the explanation of the Box 12 Codes on the W-2 tax form.
A – Any uncollected Social Security tax or RRTA tax on tips. You’ll include this amount in your total tax liability on your Form 1040.
B – Any uncollected Medicare tax on tips. You’ll include this amount in your total tax liability on Form 1040.
C – If you had group term life insurance through your workplace, the premiums for any value over $50,000 become taxable income to you and are included here.
D – Contributions to a 401k or SIMPLE 401k retirement plan.
E – Contributions to a 403b retirement plan.
F – Contributions to an SEP IRA retirement plan.
G – Contributions that you made and any employer contributions to a 457b retirement plan.
H – Contributions to a 501(c) tax-exempt plan.
J – Non-taxable sick pay.
K – Excise tax (equal to 20%) on excess “golden parachute” payments.
M – Uncollected Social Security tax or RRTA tax on the premium value of taxable group term life insurance over $50,000 for former employees.
N – Uncollected Medicare tax on the premium value of taxable group term life insurance over $50,000 for former employees.
P – Reimbursements for job relocation moving expenses paid directly to you, and not included in boxes 1, 3, or 5.
Q – Non-taxable combat pay. This isn’t subject to tax, but you can use it to calculate your Earned Income Credit if it will help.
R – Employer contributions to an Archer Medical Savings Account. These are not common anymore.
S – Employee contributions to a SIMPLE retirement plan.
T – Any adoption benefits paid to you by your employer. Use Form 8839 to calculate what portion may be taxable income.
V – Income from exercising non-statutory stock options.
W – Employer contributions to your health savings account (HSA). You will need to report this amount on Form 8889.
Y – Salary deferrals under your 409A non-qualified deferred compensation plan.
Z – Income received under 409A non-qualified deferred compensation plan.
AA – Designated Roth contributions to a 401k retirement plan.
BB – Designated Roth contributions to a 403b retirement plan.
DD – Cost of employer-sponsored healthcare (this amount is not taxable.)
EE – Designated Roth contributions to a governmental 457b retirement plan.