(a) Each loan shall be evidenced by a promissory note which shall contain a provision permitting the borrower to prepay the loan in whole or in part upon any interest payment date.(b) The promissory note shall provide for the payment of interest at a rate of one percent above the rate of interest borne by the bonds of the state last issued prior to the date such loan is made.(c) The promissory note may provide for the collection of a late charge, not to exceed two percent of any installment which is not paid within ten days of the due date thereof. Late charges shall be separately charged to and collected from the borrower.Conn. Agencies Regs. § 32-9q-6