(35 ILCS 200/18-135)
    Sec. 18-135. Taxing district in 2 or more counties.
    (a) Notwithstanding any other provisions to the contrary, in counties which have an overlapping taxing district or districts that extend into one or more other counties, the county clerk, upon receipt of the assessments from the Board of Review or Board of Appeals, and of the equalization factor from the Department, may use estimated valuations or estimated rates, as provided in subsection (b) of this Section, for the overlapping taxing district or districts if the county clerk in any other county into which the overlapping taxing district or districts extend cannot certify the actual valuations or rates for the district or districts.
    (b) If the county clerk of a county which has an overlapping taxing district which extends into another county has not received the certified valuations or rates from the county clerk of any county into which such districts overlap, he or she may subsequent to March 15, make written demand for actual or estimated valuations or rates upon the county clerk of that county. Within 10 days of receiving a written demand, the county clerk receiving the demand shall furnish certified or estimated valuations or rates for the overlapping taxing district, as pertaining to his or her county, to the county clerk who made the request. If no valuations or rates are received, the requesting county may make the estimate.
    (c) If the use of estimated valuations or rates results in over or under extension for the overlapping taxing district in the county using estimated valuations or rates, the county clerk shall make appropriate adjustments in the subsequent year. Any adjustments necessitated by the estimation procedure authorized by this Section shall be made by increasing or decreasing the tax extension by fund for each taxing district where the estimation procedures were used.
    (d) For taxing districts subject to the Property Tax Extension Limitation Law, the adjustment for paragraph (c) shall be made after the limiting rate has been calculated using the aggregate extension base, as defined in Section 18-185, adjusted for the over or under extension due to the use of an estimated valuation by the county on the last preceding aggregate extension.
(Source: P.A. 95-404, eff. 1-1-08.)