N.Y.C. Admin. Code § 28-213.1: § 28-213.1 Department penalty for work without a permit.

In addition to any penalties otherwise authorized by law pursuant to article 202 and the rules of the department, whenever any work for which a permit is required pursuant to this code has been performed without a permit, a penalty shall be imposed by the department as provided in this article.

Exception: No such penalty shall be imposed for work performed without a permit to hang or attach upon or on the outside of any building a sign that is accessory to a use on the same zoning lot, as defined in section 12-10 of the New York city zoning resolution that does not exceed one hundred fifty square feet in area, measured on one face only, or exceed one thousand two hundred pounds in weight. All such outstanding penalties imposed on or after December 28, 2017 shall be waived.