N.Y. Comp. Codes R. & Regs. tit. 21, § 5025.4 – Effect of reinstatement.

(a) A reinstatement of a prior membership shall be irrevocable.
(b) Where a member subject to the provisions of article 14 or 15 of the Retirement and Social Security Law has a prior membership not subject to either such article reinstated pursuant to this Part, the member’s obligation to make contributions pursuant to either such article, as applicable, shall be deemed to have ceased as follows:
1. (1) where the member makes application prior to June 30, 1999, such obligation shall cease as of January 1, 1999; or
2. (2) where the member makes application on or after July 1, 1999, such obligation shall cease as of the first day of the plan year in which such application is made.
  (c) Effect of transfer on obligation to make contributions pursuant to article 14 or 15 of the Retirement and Social Security Law.
  When a member subject to the provisions of article 14 or 15 of the Retirement and Social Security Law has a prior membership subject to either such article dated prior to January 1, 2010, reinstated pursuant to this Part and such member's obligation to make contributions had not previously ceased by reason of section 902(b) of the Retirement and Social Security Law, the member's obligation to make contributions pursuant to either such article, as applicable, shall cease by reason of having attained 10 or more years of membership as of the later of:
3. (1) the first day of the plan year in which the member is reinstated; or
4. (2) the first day of the month next following the day on which the member attains 10 or more years of membership after giving effect to the reinstatement of the prior membership date.
  The right of a reinstated member to cease contributions by reason of having accumulated 10 or more years of credited service shall be determined pursuant to the rules in section 5001.8 of this Title.
(d) When a member subject to the provisions of article 15 of the Retirement and Social Security Law with a membership date on or after January 1, 2010, and prior to April 1, 2012 has a prior membership subject to article 14 or 15 of the Retirement and Social Security Law dated prior to January 1, 2010 reinstated pursuant to this Part, such member's obligation to make contributions at the rate of 3.5 percent rather than at the rate of 3 percent shall cease as of the first day of the plan year in which the member is reinstated. No refund shall be made in respect of contributions made at the rate of 3.5 percent prior to such date.
(e) When a member subject to the provisions of article 15 of the Retirement and Social Security Law with a membership date on or after April 1, 2012, has a prior membership subject to article 14 or 15 of the Retirement and Social Security Law dated prior to January 1, 2010 reinstated pursuant to this Part, such member's obligation to make contributions at the rate prescribed by section 613 of the Retirement and Social Security Law, as amended by chapter 18 of the Laws of 2012, rather than at the rate of three percent shall cease as of the first day of the plan year in which the member is reinstated. No refund shall be made in respect of contributions made prior to such date.
(f) When a member subject to the provisions of article 15 of the Retirement and Social Security Law with a membership date on or after April 1, 2012, has a prior membership subject to article 15 of the Retirement and Social Security Law dated on or after January 1, 2010, and prior to April 1, 2012, reinstated pursuant to this Part, such member's obligation to make contributions at the rate prescribed by section 613 of the Retirement and Social Security Law, as amended by chapter 18 of the Laws of 2012, rather than at the rate of 3.5 percent shall cease as of the first day of the plan year in which the member is reinstated. No refund shall be made in respect of contributions made prior to such date.
(g) Where the member’s earliest prior membership in a public retirement system was in the New York City Teachers’ Retirement System and subject to chapter 522 or 523 of the Laws of 1988, such member, upon reinstatement, shall only be entitled to the rights, benefits and privileges had the member entered into membership in the system on June 30, 1976 or June 30, 1973, as applicable.
(h) Where a member’s prior membership was subject to the provisions of article 11, 14 or 15 of the Retirement and Social Security Law, the death benefit election pursuant to section 448(a), 508(a) or 606(a) of the Retirement and Social Security Law, as applicable, made by the member when the member last joined the system shall control over any election made during the prior membership.
(i) When a Tier 6 member is reinstated to a membership date on or after April 1, 2012, such member’s rate of contribution and employer projection period shall be determined by the date the member last entered the retirement system.