R.I. Gen. Laws § 45-21-44
Regular interest requirements, and the maintenance of reserves in accordance with the provisions of this chapter, are guaranteed by the respective participating municipalities, which guaranty extends only to their proportionate interests in the retirement system as determined upon the basis of the liabilities for the several benefits on account of the participating members from each municipality. Adjustment shall be made at least once every five (5) years, as provided in this chapter, in the applicable contribution rates for the municipalities for any regular interest or reserve requirements, or for any amounts above statutory requirements, as determined by actuarial valuation, in accordance with the provisions of this chapter.
R.I. Gen. Laws § 45-21-44