N.Y.C. Admin. Code § 28-105.9: § 28-105.9 Expiration.

All permits issued by the commissioner shall expire by limitation and become invalid if the permitted work or use is not commenced within 12 months from the date of issuance of the permit. Subsequent to the 12-month period following the issuance of the initial permit, all permits shall expire if the permitted work is suspended or abandoned for a continuous period of 12 months unless such permits expire earlier pursuant to applicable provisions of this code. The permit shall automatically expire upon the expiration of required insurance or if the applicant holds a license issued by the department upon the expiration or revocation of such license during the term of the permit or if the permit is not renewed.

Exception: All permits for work in a flood hazard area shall expire in accordance with the timeframes established by section G104 of appendix G of the New York city building code.