N.Y.C. Admin. Code § 13-208: § 13-208 Extra service pension credit.

Except as provided in subdivisions a and b of section 13-206 of this subchapter:

1. A member who shall have elected to contribute on the basis of retirement after twenty years of service, upon completing such period of service, may continue in the service. In such event and upon retirement for service, there shall be added to his or her annual service pension one-sixtieth of the salary received at the date of retirement for each completed additional year of service, during which years such deductions shall have been made. Any such member upon completing twenty-five years of service, shall have such deductions made at the rate of five per cent, in which event and upon retirement for service, such additional amounts also shall be added to his or her annual service pension for the years during which deductions shall have been made at the rate of five per cent.

2. A member who shall have elected to contribute on the basis of retirement after twenty-five years of service, upon completing such period of service, may continue in the service. In such event there shall be added to his or her annual service pension upon retirement for service one-sixtieth of the salary received at the date of retirement for each completed additional year of service, during which years such deductions shall have been made at the rate of five per cent.