N.Y. Lien Law § 11-c

§ 11-c. Copy of notice of lien to a contractor or subcontractor with\nrespect to public improvements liens. Within five days before or\nsimultaneously with filing a notice of lien in accordance with section\ntwelve of this chapter or the filing of an amendment of a notice of lien\nin accordance with section twelve-a of this chapter with respect to a\npublic improvement lien, the lienor shall serve a copy of such notice or\namendment by certified mail on the contractor, subcontractor, assignee\nor legal representative for whom he was employed or to whom he furnished\nmaterials or if the lienor is a contractor or subcontractor to the\nperson, firm or corporation with whom the contract was made. A lienor\nhaving a direct contractual relationship with a subcontractor or a\nsub-subcontractor but not with a contractor shall also serve a copy of\nsuch notice or amendment by certified mail to the contractor. The notice\nof lien so filed shall contain thereon or there shall be filed therewith\nproof of service of a copy of said lien upon the parties required to be\nserved pursuant to this section, and failure to file proof of such\nservice shall render the notice of lien a nullity. Any lienor, or a\nperson acting on behalf of a lienor, who fails to serve a copy of the\nnotice of lien as required by this section shall be liable for\nreasonable attorney's fees, costs and expenses, as determined by the\ncourt, incurred in obtaining such copy.\n