The burden of taxation of property in taxing districts that lie in more than one county shall be fairly apportioned as provided in Article IX, Section 7, of the Constitution of 1970.
The Department may, and on written request made before July 1 to the Department shall, proceed to apportion the tax burden. The request may be made only by an assessor, chief county assessment officer, Board of Review, Board of Appeals, overlapping taxing district or 25 or more interested taxpayers. The request shall specify one or more taxing districts in the county which lie in one or more other specified counties, and also specify the civil townships, if any, in which the overlapping taxing districts lie. When the Department has received a written request for equalization for overlapping tax districts as provided in this Section, the Department shall promptly notify the county clerk and county treasurer of each county affected by that request that tax bills with respect to property in the parts of the county which are affected by the request may not be prepared or mailed until the Department certifies the apportionment among counties of the taxing districts' levies, except as provided in subsection (c) of this Section. To apportion, the Department shall:
If the Department does not certify the percent of burden in the time prescribed, the county clerk shall use the most recent prior certification to determine the amount of tax to be raised in the county.
If the use of a prior certified percentage results in over or under extension for the overlapping taxing district in the county using same, the county clerk shall make appropriate adjustments in the subsequent year, except as provided by Section 18-156. Any adjustments necessitated by the procedure authorized by this Section shall be made by increasing or decreasing the tax extension by fund for each taxing district where a prior certified percentage was used. No tax rate limit shall render any part of a tax levy illegally excessive which has been apportioned as herein provided. The percentages certified by the Department shall remain until changed by reason of another assessment ratio study made under this Section.
To determine whether an overlapping district has met any qualifying rate prescribed by law for eligibility for State aid, the tax rate of the district shall be considered to be that rate which would have produced the same amount of revenue had the taxes of the district been extended at a uniform rate throughout the district, even if by application of this Section the actual rate of extension in a portion of the district is less than the qualifying rate.
35 ILCS 200/18-155