(a) A credit union may lend to its members at a maximum effective rate of interest, which shall not be in excess of the greater of:
(1) The applicable formula rate; or
(2) The rate of interest permitted to be charged by credit unions chartered by the federal government.
(b) For installment loans, the maximum effective rate of interest shall:
(1) Be determined in accordance with the actuarial method;
(2) Be calculated, in the case of a precomputed loan, on the assumption that all scheduled payments will be made as contracted; and
(3) Not be affected by the prepayment of the loan, in whole or in part.