N.Y.C. Charter § 1511: Section 1511. Notice of increase in assessed valuation of real property.

The department or division responsible for the assessment of real property shall, upon an increase in assessed valuation of real property, notify the owner, as recorded in said department or division, of such increase by first-class mail at least thirty days prior to the final date for filing any appeal. The department or division shall notify the commissioner of the mailing of such notices by the filing of an affidavit of such mailing in the main office of the department.