If you inherit an HSA from someone other than your spouse, you have to declare the FMV of the HSA on the date of death as income to you.
However, the rules permit you to deduct from that income any expenses incurred prior to the decedent's death but paid over the year after the decedent's death.
In this case, the amount of the expenses cannot exceed the amount of the inheritance (which was the FMV on the date of death), because TurboTax is going to subtract the expenses from the inherited amount, and this cannot be less than zero.
So either reduce the amount of expenses to the FMV on the date of death or enter the correct FMV on the date of death (yes, it says FMV at the end of the year, but it should be the date of death).
