N.Y.C. Admin. Code § 28-213.1.1: § 28-213.1.1 Penalty for work without permit on one- or two-family dwelling.

Where work has been performed without a permit on a one- or two-family dwelling the penalty shall equal six times the amount of the fee payable for the permit. Where only part of the work has been performed without a permit, the penalty shall be reduced proportionately according to the amount of work still to be performed at the time a permit is issued. Notwithstanding the foregoing, no such penalty shall be less than $600, nor more than $10,000.