410 ILCS 705/55-50
Within 20 days after the service of any order or decision of the Department of Public Health, the Department of Agriculture, the Department of Financial and Professional Regulation, or the Illinois State Police upon any party to the proceeding, the party may apply for a rehearing in respect to any matters determined by them under this Act, except for decisions made under the Cannabis Cultivation Privilege Tax Law, the Cannabis Purchaser Excise Tax Law, the County Cannabis Retailers' Occupation Tax Law, and the Municipal Cannabis Retailers' Occupation Tax Law, which shall be governed by the provisions of those Laws. If a rehearing is granted, an agency shall hold the rehearing and render a decision within 30 days from the filing of the application for rehearing with the agency. The time for holding such rehearing and rendering a decision may be extended for a period not to exceed 30 days, for good cause shown, and by notice in writing to all parties of interest. If an agency fails to act on the application for rehearing within 30 days, or the date the time for rendering a decision was extended for good cause shown, the order or decision of the agency is final. No action for the judicial review of any order or decision of an agency shall be allowed unless the party commencing such action has first filed an application for a rehearing and the agency has acted or failed to act upon the application. Only one rehearing may be granted by an agency on application of any one party.
410 ILCS 705/55-50