Section 4 (2) (c) of chapter 32 of the General Laws, as appearing in the 2022 Official Edition, is hereby amended by adding at the end thereof, the following:-

In the case of any employee of any governmental unit who is a member of the retirement system pertaining thereto, the board may allow credit, upon whatever proportionate basis it shall determine under appropriate rules and regulations which shall be subject to the approval of the actuary, for any previous period of part-time, elected, provisional, temporary, temporary provisional, seasonal or intermittent employment or service rendered by him after such a retirement system becomes operative and while he was not eligible for membership or in the case of an elected official, did not exercise his right to become a retirement system member, excluding any prescribed waiting period under the provisions of the law or under the board's rules and regulations in effect during such previous period before eligibility for membership, established either by law or board ruling in effect prior to January first, nineteen hundred and forty-six, for which such service credit was given upon attaining membership.