N.Y. Retire. & Soc. Sec. Law § 45

§ 45. Right to membership. Upon the employment of any employee whose\nright to membership in a public retirement system of the state, which\nfor purposes of this section shall include any public retirement system\nother than the New York state teachers' retirement system, has been made\noptional by the head of the retirement system involved, the employer\nshall inform the employee in writing of the right to join the system.\nEach such employee shall acknowledge the receipt of such notice by\nsigning a copy thereof and filing it with such employer; provided,\nhowever, the failure to inform such employee shall not in any way be\nconstrued to waive the requirement that membership for such an employee\ncommences only when an application for membership is filed with the\nsystem, nor shall it be construed to waive any of the eligibility\nrequirements for previous service credit.\n