N.Y.C. Admin. Code § 11-254: § 11-254 Extension of time for completion.

Where an applicant has received a certificate of eligibility but has not completed or will not be able to complete the construction or reconstruction work within thirty-six months, the board shall, upon application, extend to forty-eight months, from the time of issuance of such certificate, the time for completion of the construction or reconstruction work; provided the applicant has completed not less than two-thirds of the work as specified in the certified plans previously filed with the application at the time of such application for extension.