The Path Act of 2015 allows you to claim bonus depreciation on qualified improvement 39-year property placed in service after 2015. Qualified improvement property is defined in Sec. 168(k)(3) as improvements to the interior of any nonresidential real property placed in service after the date the building was first placed in service.
Qualified improvement property does not include expenditures to enlarge a building, for any elevator or escalator, or for the internal structural framework of the building.
Further, qualified improvement property must be placed in service after the original building was placed in service. Contrast this change with the qualified leasehold improvement requirement that an improvement be placed in service at least three years after the building was originally placed in service. I