N.Y.C. Admin. Code § 13-560: § 13-560 Monthly payments.

A pension, a pension-providing-for-increased-take-home-pay, an annuity, or a retirement allowance, granted under the provisions of this chapter, shall be paid in equal monthly instalments, and shall not be decreased, increased, revoked or repealed except as otherwise provided in section 13-553 of this chapter. The instalment for the month in which a retired contributor shall die or for any other reason cease to be a retired contributor shall be prorated.