What Does Box 12 Code AA Mean on a W-2?
Roth 401(k) contribution (after-tax). What it means, whether it is taxable, and what to do with it.
By the Easy Guides Editorial Team · Updated for 2026
Box 12 Code AA is roth 401(k) contribution (after-tax).
What Code AA means
The payoff comes later: qualified Roth 401(k) withdrawals in retirement are tax-free. Code AA just documents how much you put in.
Does Code AA affect my taxes?
Your Roth 401(k) contribution. Because it's made after tax, it's already in your Box 1 wages and there's no deduction now.
Where to find Code AA on your W-2
Look at box 12, in the middle-right of the form. It has up to four lines, labelled 12a, 12b, 12c and 12d. Those letters are only line labels. The code you want is the small letter or pair of letters printed next to the amount, and it will read AA. If you have more than four entries, your employer issues a second W-2 to carry the rest.
Not the code you were looking for? The full box 12 code list covers every letter, and the W-2 box decoder explains every box on the form.