24-month period
(A)The term “qualified rehabilitated building” means any building (and its structural components) if— (i)such building has been substantially rehabilitated, (ii)such building was placed in service before the beginning of the rehabilitation, (iii)such building is a certified historic structure, and (iv)depreciation (or amortization in lieu of depreciation) is allowable with respect to such building. (B) (i)For purposes of subparagraph (A)(i), a building shall be treated as having been substantially rehabilitated only if the qualified rehabilitation expenditures during the 24-month period selected by the taxpayer (at the time and in the manner prescribed by regulation) and ending with or within the taxable year exceed the greater of— (I)the adjusted basis of such building (and its structural components), or (II)$5,000. (ii)In the case of any rehabilitation which may reasonably be expected to be completed in phases set forth in architectural plans and specifications completed before the rehabilitation begins, clause (i) shall be applied by substituting “60-month period” for “24-month period”. (iii)The Secretary shall prescribe by regulation rules for applying this subparagraph to lessees. (C)Rehabilitation includes reconstruction.