My wife's W2 has 4 separate boxes. I always thought these were all the same.
Top left has "employee reference copy" and then there are three copies along the bottom.
All info is the same, except for box 12. 12a and 12b show different amounts in the bottom right two boxes than the top left (reference copy) and bottom left show.
These are C and D letter codes (life insurance/401k)
What does this difference mean and how do I report it? Thank you
The code C and D report the taxable amount of life insurance and your 401-K contribution. Both of those amounts would be included in your box 1 entry so your entry in box 12 would have no affect on your federal return and it would not likely affect your state return either. One of the W-2 copies should say "File with your federal return" and one should say "file with your state or local return" or something similar to that. Use those copies for the numbers you put in TurboTax. Otherwise, you may have to ask your employer which amounts are intended for your tax filing.
From my experience in my location, these box 12 numbers would be the same on all copies filed for Federal, State, City, or Local, but without knowledge of your location, I cannot explain the variation. I would first have her ask her employer the reason why these numbers differ. Her HR or Accounting Dept should be able to explain the discrepancy. It could be an error that needs correction, or it could relate to differing tax laws in various taxing jurisdictions. I do not have enough information to investigate further.
As Thomas says, one copy should say, "File with your federal return". This is the one you enter into TurboTax. So far as I know, TurboTax never asks for a different copy. As noted, you might ask your payroll department why there are differences, but this should not hold up you doing your taxes with TurboTax.
After checking, the ones with the smaller amount in 12a and 12b say to they are to be filed with the Sate Tax return (we changed states in 2022).
I was not promoted anywhere on the state section to put in separate W2 info.
How is this reported?
Once you have entered the federal copy into TurboTax, you are done. I don't see any reason to separate out the state versions of these codes or why they were reported on separate W-2s.
To put it briefly, you don't report these state versions of the codes. In fact, I would venture to say that none of us here even know why your employer did this (make the multiple copies).