Section 645 - Benefits for certain members who re-enter public service1. As used in this article the term "public retirement system" shall mean the New York state and local employees' retirement system, the New York state teachers' retirement system, the New York state and local police and fire retirement system, the New York city employees' retirement system, the New York city teachers' retirement system, the New York city board of education retirement system, the New York city police pension fund, or the New York city fire department pension fund.2. Notwithstanding any other provision of law, any person other than a retiree of a public retirement system, who previously was a member of a public retirement system and whose membership in such public retirement system ceased by reason of (i) insufficient service credit, (ii) withdrawal of accumulated contributions, or (iii) withdrawal of membership, upon rejoining such public retirement system or another public retirement system, shall be deemed to have been a member of his or her current retirement system during the entire period of time commencing with and subsequent to the original date of such previous ceased membership, provided that such person (a) makes application therefor to the administrative head of his or her current public retirement system, and (b) repays the amount refunded, if any, at the time such previous membership ceased, together with interest at the rate of five percent per annum compounded annually from the date of such refund through the date of repayment. Upon such reinstatement of date of membership, such member shall be entitled to all the rights, benefits and privileges to which he or she would have been entitled had his or her current membership begun on such original date of membership except that, solely for the purposes of granting retirement credit to members of a public retirement system other than the New York city teachers' retirement system for service credited during such previous ceased membership where such was in a public retirement system other than the member's current retirement system, such previously credited service shall be deemed to be prior service, not subsequent service. Furthermore, any such member whose original date of membership was prior to July first, nineteen hundred seventy-three shall be entitled to all the rights, benefits and privileges to which he or she would have been entitled had he or she been in active service on June thirtieth, nineteen hundred seventy-three. Any contribution made to the public retirement system pursuant to article fourteen or fifteen of this chapter by a member who rejoined his or her current system on or after July twenty-seventh, nineteen hundred seventy-six shall not be refunded.3. Anything in this section to the contrary notwithstanding, any member or retiree of a public retirement system who, prior to reinstatement to an original date of membership prior to the twenty-seventh day of July, nineteen hundred seventy-six, had obtained credit for previous service from such system pursuant to article fourteen or fifteen of this chapter shall be entitled to have any amounts paid by such member to such system for the purposes of obtaining such credit refunded to such member with interest at the rate of five percent per annum from the date of the last payment to such system.4. The provisions of this article shall be applicable to a person who is, on the date this article becomes effective, or who subsequent to such date becomes, a member of a public retirement system.N.Y. Retire. and Soc. Sec. Law § 645