R.I. Gen. Laws § 44-29-4: Deficiency determination — Interest.

If the tax administrator is not satisfied with the amount of taxes paid to him or her or with the return or returns filed with the administrator by any seller, the tax administrator may compute and determine the amount required by this chapter to be paid to the administrator, upon the basis of the facts contained in the return or returns or upon the basis of any information in his or her possession or that may come into his or her possession. The amount of his or her determination, exclusive of penalties, shall bear interest at the annual rate provided by § 44-1-7 from the tenth day after the close of the month for which the amount, or any portion of the amount, should have been paid until the date of payment.