50 ILCS 45/65
Units of local government shall provide a procedure for claiming a credit or refund of taxes, interest, or penalties paid in error. No units of local government are required to refund or credit any taxes voluntarily paid without written protest at the time of payment in the event that a local government tax is declared invalidly enacted or unconstitutional by a court of competent jurisdiction. A taxpayer shall not be deemed to have paid a tax voluntarily if the taxpayer lacked knowledge of the facts upon which to protest the taxes at the time of payment or if the taxpayer paid the taxes under duress. Unless the corporate authorities of a unit of local government expressly adopt a shorter statute of limitations for a particular tax, a statute of limitations on a claim for credit or refund may not be less than 4 years after the end of the calendar year in which payment or remittance in error was made. No unit of local government shall be required to grant a credit or refund of taxes, interest, or penalties to a person who has not paid or remitted the amounts directly to the unit of local government. Units of local government must provide, by ordinance, a rate of interest for overpayment of tax.
50 ILCS 45/65