After conducting the hearing required by Section 58-5-460, the commission shall issue a final order that:
(1) sets forth any changes that are required to the rates approved in the Initial Order issued under Section 58-5-455(5);
(2) determines the amount of any overcollection or undercollection by the utility that resulted from collection of the rates authorized in the Initial Order as compared to the rates authorized in the final order issued under this section; and
(3) establishes a credit to refund the amount of any overcollection, or a surcharge to collect the amount of any undercollection that arose during the time that the rates approved in the Initial Order were collected, and requires the utility to apply the credit or surcharge until such time as the overcollection or undercollection is exhausted.
The commission shall issue any final order required under this section by April fifteenth of the year following the year in which the monitoring report was filed. The order shall make the corrected rates and the credit or surcharge, if any, effective as of the first billing cycle of May of that year.
The provisions of Sections 58-5-330 and 58-5-340 concerning rehearing and appeal shall apply to the orders issued pursuant to this section.