PRINCIPAL BALANCE; INCLUSION OF DOCUMENTARY FEE

(a) The principal balance under a retail installment contract is computed by: (1) adding: (A) the cash price of the commercial vehicle; (B) each amount included in the retail installment contract for an itemized charge; and (C) subject to Subsection (c), a documentary fee for services rendered for or on behalf of the retail buyer in handling and processing documents relating to the sale of the commercial vehicle; and (2) subtracting from the results under Subdivision (1) the amount of the retail buyer's down payment in money, goods, or both. (b) The computation of the principal balance may include an amount authorized under Section 353.402(b). (c) For a documentary fee to be included in the principal balance of a retail installment contract: (1) the retail seller must charge the documentary fee to cash buyers and credit buyers; and (2) the documentary fee may not exceed an amount agreed to in writing by the retail seller and retail buyer.