Box 12 — Box 12 codes (overview)
Coded amounts for retirement deferrals, health coverage, and other items that do not fit Boxes 1–11.
What it means
Box 12 uses letter codes. Common ones include D (traditional 401(k) deferrals), AA (Roth 401(k) deferrals), C (group-term life over $50,000), and W (HSA contributions). Multiple codes can appear. See the specific code pages on this site for how each affects AGI and planning.