The amount with code "W" in box 12 of your W-2 is the
sum of the amounts that your
employer contributed to your HSA AND that
you contributed through a payroll deduction scheme. If either you or your employer made contributions to your HSA (as the copy printed at home would seem to indicate), then the W-2 that you received in the mail is incorrect.
On the W-2 that you printed at home, look to see if that W-2 is annotated with the word "Corrected". If so, this is the W-2 you should use. Mark the other one that you didn't use it and put it in your tax file.
But if neither copy shows Corrected, you need to call your HR department and ask them why you have two different versions and which one you should use.
If you or your employer did make contributions to your HSA, then the one printed at home is likely correct, but you need to confirm it. Also confirm that the amount contributed to the HSA (code W) was subtracted form wages in boxes 1, 3, and 5 on the W-2 - that amount should have been removed from your wages on your W-2.
You want to be sure that you are not taxed on these contributions to your HSA.
[minor edit 1/17/2019 11:36 CST]
