for HSA contributions, which of the box 12's do i need to fill in (12a, 12b or 12c)?

[dmertz · Accepted solution]

Enter all of the box-12 boxes in the corresponding box-12 boxes on TurboTax's W-2 form, nowhere else in TurboTax.  TurboTax automatically picks up the code-W entry from the W-2 form, so do not enter this amount separately in the HSA section.