R.I. Gen. Laws § 36-7-25
Each city, town, or agency of the state participating under the federal state agreement as herein described shall make payment to the general treasurer of the state at such time or times as he or she may prescribe of the contributions with respect to salaries or wages as herein defined equal to the sum of the taxes which would be imposed by §§ 3101 and 3111 of the federal Insurance Contributions Act, 26 U.S.C. §§ 3101, 3111, if the services covered by the federal state agreement to which the city, town, or agency of the state has subscribed constituted employment within the meaning of that act. The payments shall be made to the state for the purpose of meeting the requirements of § 36-7-3(2). In the event any city, town, or agency of the state does not make payment of the required amounts at the time or times the amounts shall be due and payable, there shall be added as a part of the amounts payable, interest at the rate of twelve percent (12%) per annum from the date the amounts shall be due until paid.
R.I. Gen. Laws § 36-7-25