SECTION 1. Chapter 32 of the General Laws is amended in subsection (1) of section 4 by adding the following new subsection:—(t) Notwithstanding the provisions of any general or special law to the contrary, a member in service of the state employees’ or teachers’ retirement system or a retirement system of a city, town, county, region or district as defined in section one who served as a volunteer in the Peace Corps, Volunteers in Service to America (VISTA), AmeriCorps VISTA, Teacher Corps, the Commissioned Corps of the United States Public Health Service, or the Commissioned Corps of the National Oceanic and Atmospheric Administration who completes fifteen or more years of membership service shall receive full credit for the period of such volunteer service up to, but not exceeding three years. Eligibility for said creditable service shall be conditioned upon payment, in one sum or in installments upon such terms as the state retirement board or the teacher’s retirement board or a retirement system of a city, town, county, region or district may provide, into the annuity savings fund of the state employees, teachers retirement system or a retirement system of a city, town, county, region or district an amount equal to the contributions such member would have otherwise paid into the retirement system for the period of volunteer service based upon the annual salary the member received in the first year of membership service after said volunteer service; provided further that such creditable service shall not be allowed for any period of active service for which said volunteer has received credit pursuant to paragraph (f) of subsection (1) of section 4 of chapter 32.