What this line means
The fourth and final entry slot for coded benefits in Box 12. Same format and code set as 12a through 12c. If your employer reports more than four coded items, they issue an additional W-2 (a “W-2c” is not used for this — they simply produce a second W-2 with the same employer information and the additional Box 12 codes).
Does this apply to you?
- You have four or more distinct coded benefit types from your employer
- Your employer uses Box 12d for an additional coded amount that did not fit in the first three slots
- You want to verify that all coded benefits across Boxes 12a-12d are accounted for on your return
Easy to overlook
Code DD is the most common Box 12d entry — and it is not taxable Many employers use the first three Box 12 slots for retirement contributions, HSA contributions, and other items, leaving Code DD (cost of employer-sponsored health coverage) for Box 12d. The DD amount often exceeds $20,000 and alarms filers who think it is unreported income. It is purely informational — required by the ACA for transparency, not for taxation. 1 ACA employer reporting — Code DD health coverage cost
Four slots is the maximum per W-2, but not per employer If your employer needs to report five or more codes, they produce a second W-2 with the overflow entries. When entering W-2 data, make sure you enter all W-2 forms from the same employer. Tax software treats each W-2 as a separate entry, so the system will handle multiple W-2s from one employer correctly as long as you enter both. 2 IRS W-2 Instructions — Box 12 code definitions
Watch out for this
Ignoring a second W-2 from the same employer. If your employer issued two W-2s to fit all Box 12 codes, both must be entered. The second W-2 typically has Box 1 showing $0 and only Box 12 entries. Filers who see a $0-wage W-2 assume it is a duplicate and skip it, which means the coded benefits on that form go unreported.
Footnotes
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IRS, Form W-2 Reporting of Employer-Sponsored Health Coverage. https://www.irs.gov/affordable-care-act/form-w-2-reporting-of-employer-sponsored-health-coverage ↩
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IRS Instructions for Forms W-2 and W-3, Box 12 Codes. https://www.irs.gov/instructions/iw2w3 ↩