N.Y.C. Admin. Code § 28-213.1.2: § 28-213.1.2 Penalty for work without permit on other than one- or two-family dwelling.

The penalty for work without a permit on buildings other than one- or two-family dwellings shall be 21 times the amount of the fee payable for such 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 $6,000, nor more than $15,000.