A retail installment contract under The Home Improvement Sales and Finance Act may provide that the finance charge be calculated on a simple-interest basis subject to the following provisions:(1) Instead of a finance charge computed on the amount financed as determined under s. 520.73(2), the seller may compute the finance charge at a simple-interest rate equivalent to the finance charge permitted by s. 520.78(1) on the unpaid balance as it changes from time to time or by any other method. (2) The language in s. 520.78(1) which provides that the finance charge may be computed on the basis of a full month for any fractional-month period in excess of 15 days shall not be applicable to a simple-interest contract. (3) The provisions of s. 520.84 which prescribe a refund credit upon prepayment in full before maturity of the unpaid balance of a retail installment contract shall not be applicable to a simple-interest contract. (4) In the event the unpaid balance of a retail installment contract is extended, deferred, renewed, or restated, the holder may compute the refinance charge in accordance with the provisions of this section.
