105 ILCS 5/9-11
In addition to the notice requirements of the general election law, whenever a proposition to increase a school tax rate is submitted to be voted upon by the voters of any district the notice of such election shall include an estimate of the approximate amount of taxes extendible under the maximum rate then in force and an estimate of the approximate amount of taxes extendible under the proposed increased rate, such amounts being computed upon the last known full, fair cash value; provided that any error, miscalculation or inaccuracy in computing such amounts shall not invalidate or affect the validity of any rate so increased. The board of directors shall make such estimate and the secretary shall certify such amount to the election authority as part of the certification of the proposition as required by the general election law. Such estimate shall appear on the ballot on which the proposition is printed, but shall not appear as a part of the proposition.
105 ILCS 5/9-11