You would enter this as Other Income.
Since this is, in effect, recapture of deductions you claimed on past tax returns.
To enter in TurboTax go to:
Federal Taxes -> Wages & Income -> I'll choose what I work on -> scroll to the bottom and under Less Common Income select Start (or Update) for Miscellaneous Income.... You'll find all sorts of other income categories in there. If none of those shown fit the bill then pick Other reportable income and you can enter your own description(s) and amount(s).