69-3-302. Changes in schedules. (1) Except as provided in 69-3-308, a change may not be made in any schedule, including schedules of joint rates, except as approved by the commission, upon the passage of 9 months, or by operation of 69-3-907(1). If the 9-month time period expires prior to commission approval of a schedule, a utility may waive the time period.
(2) Notwithstanding any provision of this title to the contrary, other than rate adjustments made pursuant to 69-3-308, the rates, tolls, or charges set forth in any schedule filed with the commission pursuant to 69-3-301 must become effective and be lawful rates, tolls, or charges for the utility service rendered 9 months after the date upon which the schedule was filed under the rules of practice and procedure for filing as adopted by the commission or upon commission approval, whichever occurs first, unless the utility waives the 9-month time period. However, if the rates, tolls, or charges become effective because of the passage of 9 months, the revenue collected is subject to rebate, plus interest at an annual rate determined by the commission, to the extent that the rates, tolls, or charges ultimately approved by the commission in its final decision produce revenue that is less than that collected under the filed schedules. In the case of an investor-owned utility, the interest rate set by the commission may not exceed the cost of equity capital as last determined by the commission.
(3) The commission may prescribe rules necessary to effectively administer this section.