When selling a rental property, you have to pay taxes on the recapture of the depreciation that you should have claimed, even if you never actually claimed it.  Yes, that's as bad as it sounds.

There is a solution, but it's complicated.  In the year of sale, the IRS provides the ability to use DCN 107 to fix past depreciation using form 3115.  It's a complicated form to complete, with supporting statements and calculations, but the result is you can claim the past missed depreciation error, and recapture it in the same year.