What Does Box 12 Code BB Mean on a W-2?
Roth 403(b) contribution (after-tax) — what it means, whether it's taxable, and what to do with it.
By the Easy Guides Editorial Team · Updated for 2026
Code BB in Box 12 of your W-2 means roth 403(b) contribution (after-tax). Tax treatment: After-tax.
What Code BB means
Like a Roth 401(k), the benefit is tax-free qualified withdrawals later, not a deduction now.
Does Code BB affect my taxes?
Your Roth 403(b) contribution — the after-tax version of a 403(b). It's already included in your Box 1 wages, so there's no deduction.
Where to find Code BB on your W-2
Box 12 has up to four slots — labeled 12a, 12b, 12c, and 12d. Each slot shows a letter code and a dollar amount. The 12a–12d labels are just line numbers; the actual code is the small letter next to the money. So "12a: BB 5,000" means Code BB with a $5,000 amount. When you file, enter the code and amount exactly as shown.