35 ILCS 200/18-45
Except as provided below, each county clerk shall estimate and determine the rate per cent upon the equalized assessed valuation for the levy year of the property in the county's taxing districts and special service areas, as established under Article VII of the Illinois Constitution, so that the rate will produce, within the proper divisions of that county, not less than the net amount that will be required by the county board or certified to the county clerk according to law. Prior to extension, the county clerk shall determine the maximum amount of tax authorized to be levied by any statute. If the amount of any tax certified to the county clerk for extension exceeds the maximum, the clerk shall extend only the maximum allowable levy.
The county clerk shall exclude from the total equalized assessed valuation, whenever estimating and determining it under this Section and Sections 18-50 through 18-105, the equalized assessed valuation in the percentage which has been agreed to by each taxing district, of any property or portion thereof within an Enterprise Zone upon which an abatement of taxes was made under Section 18-170. However, if a municipality has adopted tax increment financing under Division 74.4 of Article 11 of the Illinois Municipal Code, the county clerk shall estimate and determine rates in accordance with Sections 11-74.4-7 through 11-74.4-9 of that Act. Beginning on January 1, 1998 and thereafter, the equalized assessed value of all property for the computation of the amount to be extended within a county with 3,000,000 or more inhabitants shall be the sum of (i) the equalized assessed value of such property for the year immediately preceding the levy year as established by the assessment and equalization process for the year immediately prior to the levy year, (ii) the equalized assessed value of any property that qualifies as new property, as defined in Section 18-185, or annexed property, as defined in Section 18-225, for the current levy year, and (iii) any recovered tax increment value, as defined in Section 18-185, for the current levy year, less the equalized assessed value of any property that qualifies as disconnected property, as defined in Section 18-225, for the current levy year.
35 ILCS 200/18-45