N.Y. LIE Law § 16

§ 16. Assignment of contracts and orders for public improvement to be\nfiled. No assignment of a contract for the performance of labor or the\nfurnishing of materials for a public improvement, or of the money, or\nany part thereof, due, or to become due, therefor, nor an order drawn by\nthe contractor or sub-contractor upon the public corporation, or the\nhead of the department or bureau having charge of the construction or\ndemolition of such public improvement, or the financial officer of the\npublic corporation, or other officer or person charged with the custody\nand disbursement of the corporate funds applicable to the contract for\nsuch public improvement, shall be valid unless such assignment or order,\nor a copy thereof, be filed within twenty days after the date of such\nassignment of contract, or such assignment of money, or such order, with\nthe head of the department or bureau having charge of such construction\nor demolition, and with the financial officer of the public corporation\nor other officer or person charged with the custody and disbursement of\nthe corporate funds applicable to the contract for such public\nimprovement, and such assignment or order shall have effect and be\nenforceable from the time of such filing, and no such assignment or\norder shall have any validity until the same shall have been so filed,\nand every such assignment or order, not filed, shall be absolutely void\nas against a subsequent assignee in good faith and for valuable\nconsideration, whose assignment or order is first duly filed. The\nfinancial officer of the public corporation, or other officer or person\nwith whom the assignment order, or copy thereof, is filed, shall enter\nthe facts relating to the same in the lien book or other book provided\nfor such purpose.\n