220 ILCS 5/9-226

In any general rate increase proceeding in which Section 9-225 of this Act applies, the following materials shall be made available to the Commission: (a) Copies of all advertisements and scripts included in the operating expense, listing the production costs for each ad, the publication schedule and costs for each ad; (b) Copies of all advertisements included in the operating expense purchased on a cooperative basis with manufacturers, developers or others and the company's cost for each ad; and (c) All expenses incurred by the utility included in the operating expense for ads or scripts produced by a trade association including all monies paid to the association for advertising purposes, either in the form of dues, assessments or subscriptions.