35 ILCS 200/17-20
The Department shall, after publishing its tentative equalization factor and giving notice of hearing to the public in a newspaper of general circulation in the county, hold a hearing on its estimate not less than 10 days nor more than 30 days from the date of the publication. The notice shall state the provided hearing platform and accessibility instructions, date, and time of the hearing, the basis for the estimate of the Department, and further information as the Department may prescribe. The Department shall, after giving a hearing to all interested parties and opportunity for submitting testimony and evidence in support of or adverse to the estimate as the Department considers requisite, either confirm or revise the estimate so as to correctly represent the considered judgment of the Department respecting the estimated percentage to be added to or deducted from the aggregate assessment of all locally assessed property in the county except property assessed under Sections 10-110 through 10-140 or 10-170 through 10-200. Within 30 days after the conclusion of the hearing the Department shall mail to the County Clerk, by certified mail, its determination with respect to such estimated percentage to be added to or deducted from the aggregate assessment.
35 ILCS 200/17-20