Section 1603 - Payment in full before maturity; acceleration of balance due(a) Notwithstanding the provisions of any contract to the contrary, any buyer may pay the contract in full at any time before maturity and in so paying it shall receive a refund credit thereon for such anticipation. In addition, pursuant to any contract provision so stating and subject to the restrictions of this act, as amended, a seller or holder may accelerate the balance due on an installment sales contract, but shall provide a refund credit thereon calculated as of the date of the acceleration. The amount of any such refund credit shall be computed pursuant to the actuarial method. Actuarial method means the method of allocating payments made on a debt between the amount financed and the finance charge pursuant to which a payment is applied first to the accumulated finance charge and any remainder is subtracted from the unpaid balance of the amount financed. Where the amount of the credit for anticipation of payment is less than one dollar ($1) no refund need be made. Where the earned service amounts to less than the minimum service charge, there may be retained an amount equal to the minimum service charge applicable.(b) As used in the section "actuarial method" means the method of allocating payments made on a debt between the amount financed and the finance charge at the interest rate stated in the contract, as defined in Regulation Z, Appendix J, adopted under the Federal Truth in Lending Act. 1966, Special Sess. No. 1, Oct. 28, P.L. 55, art. VI, § 603. Amended 1982, March 25, P.L. 199, No. 68, § 5, imd. effective.