50 ILCS 45/40
Units of local government have an obligation to provide, by ordinance, a procedure for appealing a determination of tax due or an assessment. Local governments must provide to taxpayers a written statement of rights whenever the local government issues a protestable notice of tax due, a bill, a claim denial, or a notice of claim reduction regarding any tax. The statement must explain the reason for the assessment, the amount of the tax liability proposed, the procedure for appealing the assessment, and the obligations of the unit of local government during the audit, appeal, refund, and collection process. In no event may a taxpayer be provided a time period less than 45 days after the date the notice was served in which to protest a notice of tax determination or notice of tax liability. Any notice of tax assessment due must be sent by United States registered or certified mail. The unit of local government must also adopt procedures for opening up any closed protest period or extending the protest period upon the showing of reasonable cause by the taxpayer and full payment of the contested tax liability along with interest accrued as of the due date of the tax.
50 ILCS 45/40