105 ILCS 5/34-53.1
When a supplemental budget has been adopted by the board of education under Section 34-44.1 the board of education may levy supplemental taxes which shall not exceed the amount of the increase in revenues projected in the supplemental budget nor exceed the maximum rates of taxes which the board is authorized by law to levy for the fiscal year to which the increase applies for the respective purposes. With respect to any supplemental levy based on an increase in the value of taxable property in the school district, such supplemental levy shall be adopted within 60 days of the date of the final certification of the equalization rate by the Department of Revenue to the county clerk as provided in the Property Tax Code, irrespective of whether the adoption occurs within or after the close of the fiscal year to which the increase applies. The board is authorized to levy supplemental taxes pursuant to this Section.
105 ILCS 5/34-53.1