N.Y.C. Admin. Code § 12-125: § 12-125 Retired employees; change of options.

Notwithstanding any other law to the contrary, no beneficiary shall be permitted to change any optional selection after it has become effective, provided, however, that if:

(a) a retired member nominates the spouse of such member as the survivor beneficiary under option two or three of section 13-177 of the code, or if a retired member nominates the spouse of such member under option four of such section to receive payment of an annual benefit as a survivor; and

(b) such person so nominated ceases by causes other than death to be his or her spouse or is separated from such spouse; then the board of trustees shall have authority to permit the change of the optional benefit to the maximum benefit that is the actuarial equivalent by and with the consent of all parties.