35 ILCS 200/20-10
When the copy of the tax bill is mailed by the collector to the owner or person at or in care of the address of a mortgage lender, the mortgage lender, within 15 days of receiving the copy, shall furnish and mail an additional copy of the bill to each mortgagor of the property at his or her last known address as shown on the records of the mortgage lender. However, if the property referred to in the copy is situated in a county which uses the estimated or accelerated billing methods, only an additional copy of the bill for the final installment of taxes due with respect to the real property shall be furnished and mailed by the mortgage lender to the mortgagor. A copy may be used by the collector in receipting for the tax paid, and a copy or record shall be retained by the collector.
35 ILCS 200/20-10