N.Y. Town Law § 153

§ 153. Transfers. Transfers from one town police department to another\ntown or village police department in the same county may be made upon\nthe mutual consent of the appointing officers of the departments\naffected. Any member of such police force who is or has been transferred\nshall receive credit with the department to which he is transferred for\ntime served on the police force or in the department of any village or\ntown within the same county, as though the full time had been served\nwith the department to which he has been transferred, for purposes of\nseniority, promotion, pensions and general administration.\n