For Refunded Service:
If you terminate your public service and take a refund of your accumulated total deductions and later return to public service, you may re-establish your prior creditable service by buying it back. But, you will begin as a new member, making contributions at the current rate. Of note, if a person who is a member of a retirement system as of February 16, 2012 fails to buy back prior service before April 2, 2013, such a member will have to pay actuarial assumed interest instead of buy back interest on the purchase. Those who re-enter or re-establish service on or after February 16, 2012 will also have until April 2, 2013 to either buy back certain prior service or they must pay actuarial assumed interest instead of buy back interest on the purchase.
PERAC link to more information:
For prior non-membership service:
For Members of the System may only purchase and receive credit for past non-membership service rendered in a member unit of the System consistent with the provisions of M.G.L. c. 32, § 4(2)(c), or service rendered in a member unit of the System as a reserve or permanent-intermittent or [sic] police officer or as a reserve, permanent-intermittent or call firefighter pursuant to Section 4(2)(b), or if the past service was rendered under the jurisdiction of another retirement system, such service may only be purchased if rendered in a temporary, provisional or substitute capacity, provided that the individual was excluded from membership in the other retirement system. All prior non-membership service shall be calculated with 150 hours being the equivalent of one (1) month of creditable service.