The interior improvements qualified for a special asset class called Qualified Improvement Property (QIP). When a building is renovated, many interior assets that normally would be allocated to a 39-year depreciation period are then eligible for a 15-year depreciation period instead (plus bonus depreciation). Our engineers were challenged to discern between improvements made to the structure and building envelope versus interior modifications. QIP on this property was significant, enabling the client to gain substantial tax benefits.