Section 42-11.1-6 - Computation of interest payment(a) Interest payments on amounts due to a contractor according to this chapter shall be paid to the contractor for the period beginning on the date after the required payment date and ending on the day a proper invoice was approved for payment by the controller's office.(b) Each state department, agency, or project administering state funds shall calculate and pay interest upon payment of the principal sums due. Interest payment shall accompany payment of the net amount due for goods and service.(c) Agencies shall not require companies to petition, invoice, bill, or wait any additional days to receive interest due.(d) Interest shall be paid at a rate equal to the prime interest rate as reported on the money market page of the Wall Street Journal published on the first regular business day of each month.(e) Unpaid interest shall compound every month overdue.(f) Interest shall be paid from funds appropriated to the particular state agency with which a contract exists. If more than one state agency has caused a late payment, with respect to a particular contract, each state agency shall bear a proportionate share of the interest payment.R.I. Gen. Laws § 42-11.1-6