35 ILCS 200/21-340

Recovery of amount of tax or special assessment paid by purchaser at erroneous sale. In addition to all other remedies, when the purchaser or assignee of a certificate of purchase that has been declared an erroneous sale, has paid any tax or special assessment upon the property sold, which was not paid by the owner of the property and was not refunded to the tax purchaser or assignee by the county, the purchaser or assignee may recover from the owner the amount he or she paid, with 10% interest, as money paid for the owner's use.