(2) No double benefit Any deduction allowable for costs taken into account in computing the amount of the credit for qualified abatement expenses shall be reduced by the amount of such credit attributable to such costs. . (c) Conforming amendments (1) Section 1324 of title 31, United States Code, is amended by inserting , 36C, 36D after , 36B . (2) The table of sections for subpart C of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after the item relating to section 36B the following new items: Sec. 36C. Accessibility and fire prevention expenses for historic buildings. Sec. 36D. Abatement of hazardous substances in historic buildings. . (d) Effective date The amendments made by this section shall apply to amounts paid or incurred in taxable years beginning after the date of the enactment of this Act.