Wisconsin Statutes Utilities (Ch. 196 to 201) § 196.645. Rate changes

(1) The commission, upon complaint or upon its own motion, may proceed to investigate and determine whether a public utility's rates should be changed by reason of a change in the cost of an energy, commodity or service resulting from a change in charges for the energy, commodity or service if:

(2) The commission may make a change in rates under sub. (1) effective as of the effective date of the order of the federal authority prescribing the change in charges.

(3) Notwithstanding ss. 196.60(3) and 196.604, the commission may determine and require payment by the public utility to its consumers of any sums which the public utility received from the consumers subsequent to the effective date of its order under this section and which are in excess of the rates prescribed by the commission under this section.