Subsection (1) of section 4 of chapter 32 of the General Laws as appearing in the 2006 Official Edition, is hereby amended by inserting after paragraph (g½) its following paragraph:—  (g¾) The period or periods during which any member in service of the teachers retirement system or any teacher who is a member of the State-Boston retirement system whose employment was terminated due to a reduction in force and had established membership in the Massachusetts contributory retirement system and was subsequently employed as a teacher in any governmental unit shall be allowed creditable service for such unemployment on a proportionate basis which the board shall determine according to rules and regulations adopted by the board and approved by the commission, provided, that no such credit shall be allowed unless such member has paid into the Annuity Savings Fund of the systems, in one lump sum or installments, upon such terms and conditions as the board may prescribe, an amount equal to the deductions that would have been withheld had the member continued in service, as determined by the board, together with regular interest. No credit shall be allowed and no payment shall be accepted under this paragraph until such member shall have completed 10 or more years of membership service. The maximum creditable service allowed under this paragraph for any member shall not exceed 4 years.