Section 06.40.120 - Service charge; interest rate; prepayment(a) A premium finance company may not charge, contract for, receive, or collect a service charge other than as permitted by this chapter.(b) The service charge is to be computed on the balance of the premiums due, after subtracting the down payment made by the borrower in accordance with the premium finance agreement, from the effective date of the insurance coverage for which the premiums are being advanced, to and including the date when the final payment of the premium finance agreement is payable.(c) The service charge may not exceed interest at the nominal annual rate of 15 percent plus an additional charge of $10 per premium finance agreement which need not be refunded upon cancellation or prepayment. However, any borrower may prepay a premium finance agreement in full at any time before the due date of the final payment and in that event the unearned service charge shall be refunded. The amount of any refund shall be calculated in accordance with regulations adopted by the commissioner.