When you were in the TurboTax HSA interview, and TurboTax told you that you had excess contirbutions, then if the excess contributions came from the code W amount in box 12 of your W-2, TurboTax immediately added your excess to Other Income on Line 8 on Schedule 1 (Form 1040), where it will be taxed.
If your excess was because of a direct contribution that you made (not through your employer), then the amount that would have been reported on line 12 of Schedule 1 is reduced by the amount of the excess.
In either case, you don't have to do anything and please don't go asking your employer for a corrected W-2.
TurboTax has already taken care of what needs to be done on the tax return side.
[Edited 3/20/2020 1:36pm CDT - updated for 2019]
