N.Y. Comp. Codes R. & Regs. tit. 21, § 5014.4 – Procedure for electing an option.

(a) Upon filing an application for retirement, a member may elect one of the optional allowances available to such member, as applicable. In order to be valid, such election must be on a form supplied by the system or in a written request.
(b) In the case of service or deferred retirement, such election must be duly executed and acknowledged, and must be filed with the system no later than 30 days following the date on which the retirement becomes effective.
(c) In the case of disability retirement, such election must be duly executed and acknowledged, and, except as provided in section 511 of the Education Law, must be filed with the system no later than the later of:
1. (1) 30 days following the date on which the retirement application is approved by the system's retirement board for members retiring under section 511 of the Education Law or under section 605 of the Retirement and Social Security Law or by the system for members retiring under section 506 or 507 of the Retirement and Social Security Law; or
2. (2) 30 days following the date on which retirement occurs.
(d) A member's election of an option must be unconditional.