Del. Code tit. 30, § 1112

A resident individual shall be allowed a credit against such individual’s tax otherwise due under this chapter in accordance with the provisions of the Historic Preservation Tax Credit Act (Chapter 18 of this title), which credits shall be against any taxes imposed under this chapter; provided however, that all claimed credits are accompanied by a Certificate of Completion issued by the Delaware State Historic Preservation Office certifying that such credits have been earned in compliance with that act.