N.Y. Gen. Mun. Law § 209-j

§ 209-j. Mutual aid programs in counties. The board of supervisors in\nany county may appropriate and expend such sums as it may deem necessary\nand proper for the establishment and maintenance of a county mutual aid\nplan in cases of fire and other emergencies in which the services of\nfirefighters would be used and may prescribe the method of auditing or\napproving expenditures under any such appropriation. Expenses incurred\nby any city, town, village or fire district participating in such mutual\naid plan shall be a lawful municipal or fire district charge to be paid\nin the same manner as other like charges.\n