(35 ILCS 200/18-156)
    Sec. 18-156. Correction of apportionment of taxes for a district in 2 or more counties.
    (a) Definitions. For the purposes of this Section, these definitions shall apply:
    "Apportioned property tax levy" means the total property tax extension of a taxing district in one or more counties that has been apportioned by the Department pursuant to Section 18-155.
    "Over-apportionment" means that any single county's share of an apportioned property tax levy is subsequently determined to exceed 105% of what that county's share should have been.
    (b) If, subsequent to the calculation of an apportioned property tax levy, the Department determines that an over-apportionment has taken place, the Department shall notify the county clerk and county treasurer of each county affected by the incorrect apportionment and shall provide those county clerks and county treasurers with correct apportionment data.
    (c) If the notification under this Section is made prior to the due date of the final installment of property tax payments for that taxable year, the county treasurer of a county where an over-apportionment has taken place may, at the treasurer's sole discretion, issue a refund of the over-apportioned amount by either a reduced final installment, a refund of taxes paid, or both, to each taxpayer who is entitled to a refund because of the over-apportionment. Additionally, if the treasurer of the county where an over-apportionment has taken place issues a refund under this subsection, the county treasurer of each other county affected by the incorrect apportionment shall issue a corrected final installment or an additional bill for the amount owed as a result of the under-apportionment of that county's share of the property tax levy to each taxpayer whose taxes were underpaid as a result of the apportionment error.
    (d) Any refund issued under subsection (c) due to any over-apportionment may be made from funds held by the county treasurer for the specific taxing district that was the subject of the over-apportionment; once those funds have been disbursed to the taxing districts, the authority of the county treasurer to issue refunds under subsection (c) ends.
    (e) This Section applies for taxable year 2015 and thereafter.
(Source: P.A. 99-335, eff. 8-10-15.)