A credit union may require a partial prepayment that is made on a loan secured by a lien or mortgage on or other type of security interest in real property to be made:

1. (1) on the date monthly installments are due; and
2. (2) in the amount of that part of one or more monthly installments that would be applicable to principal.

Acts 1997, 75th Leg., ch. 1008, Sec. 1, eff. Sept. 1, 1997.