(a) To determine whether a loan secured in any part by an interest in real property, including a lien, mortgage, or security interest, is usurious, the interest rate is computed by amortizing or spreading, using the actuarial method during the stated term of the loan, all interest at any time contracted for, charged, or received in connection with the loan.
(b) If a loan described by Subsection (a) is paid in full before the end of the stated term of the loan and the amount of interest received for the period that the loan exists exceeds the amount that produces the maximum rate authorized by law for that period, the lender shall:
(1) refund the amount of the excess to the borrower; or
(2) credit the amount of the excess against amounts owing under the loan.
(c) A lender who complies with Subsection (b) is not subject to any of the penalties provided by law for contracting for, charging, or receiving interest in excess of the maximum rate authorized.