815 ILCS 375/22.1
(c) If any advertisement to which this Section applies states the amount of the down payment, if any, the amount of any installment payment, the dollar amount of any finance charge, or the number of installments or the period of repayment, then the advertisement must state all of the following items:
(4) The rate of the finance charge expressed as an annual percentage rate.
An advertisement which complies with the federal Truth in Lending Act, amendments thereto, and any regulations issued or which may be issued thereunder, shall be deemed to be in compliance with the provisions of this Section.
(from Ch. 121 1/2, par. 582.1)
(Source: P.A. 82-169.)