R.I. Gen. Laws § 36-9-26: Credits for layoffs.

(a) Members who are laid off for any reason and are not on leave without pay may purchase up to one years’ credit for retirement purposes; provided the member did not withdraw his or her retirement contributions while on layoff, and returns to active membership; provided, further, that the member purchases that credit upon his or her return to service from the layoff and pays into the retirement system the full actuarial cost as defined in § 36-8-1(10).

(b) The retirement board shall fix and determine rules and regulations to govern the provisions of this section.