Section 220 ILCS 5/9-253 - Refunds(a) If the Commission or a court determines that a public utility has overcharged its customers and orders that a refund be made to customers of the utility, a portion of the refund shall be set aside during the refund period or for 120 days after the refund is ordered, whichever is longer, and shall be used to pay refunds to customers who were overcharged and are no longer customers of the utility. The Commission shall determine the amount to be set aside for refunds to former customers. The Commission shall periodically review the appropriateness of the amount of funds set aside for purposes of compensating former customers and make adjustments as needed.(b) The utility ordered to make the refund shall notify the public in the form designated by the Commission. In determining the form of the notice, the Commission shall take into account the effectiveness of the format in reaching former customers as well as the administrative costs of notifying past customers.(c) A portion of the funds set aside for refunds to former customers may be used to cover administrative costs of the refund. The Commission shall determine the reasonableness of such administrative costs and shall establish a formula for determining how much of the funds may be used for administrative costs.(d) Only a former customer who was a customer of the utility during the period of the overcharges and who files a claim with the utility during the refund period or within 120 days after the refund is ordered, whichever is longer, and proves that he was a customer of the utility during the period of overcharges shall be entitled to a refund under this Section. A claim for a refund shall be in writing on a form provided by the utility. For purposes of this Section, "prove" means providing a copy of a past bill for utility services which shows that the claimant was a customer of record of the utility during the period of overcharges. The claimant shall not be obligated to provide a past bill if there is less than 24 months between the date of the refund and the period of the service to which the refund applies.(e) If a former customer claims a refund and owes a past due amount to the utility, the refund amount shall be reduced by the amount the customer owes the utility and that past due amount shall be returned to the utility.(f) Interest shall accrue on the funds set aside until all moneys have been paid out to customers.(g) At the end of the refund period or 120 days after the refund is ordered, whichever is longer, any balance remaining after all legitimate claims for refunds have been paid shall be refunded to current customers of the utility as a credit on their bills.(h) The Commission shall determine the formula on how amounts for refunds to former customers shall be calculated.(i) This Section does not apply to refunds which were ordered prior to the effective date of this amendatory Act of 1994.(j) This Section does not apply to refunds ordered in reconciliation proceedings pursuant to Section 9-220 of the Public Utilities Act.P.A. 88-639, eff. 9/9/1994.