(a) As soon as practical each year, the department shall compute the reserve liability of each stipulated premium company that has outstanding insurance policies.
(b) To make the computations, the department:
(1) shall use the net premium basis in accordance with the reserve table and interest rate adopted by the stipulated premium company and approved by the commissioner; and
(2) may use group methods and approximate averages for fractions of a year.
(c) The reserve liability may be computed on not more than a one-year preliminary term with allowance for any deficiency reserve under Section 884.453.