105 ILCS 5/34-47
Subsequent to the public hearing provided for in Section 34-46 and before final action on the budget, the board may revise, alter, increase, or decrease the items contained therein, but the aggregate amount finally appropriated by the budget, including any subsequent amendment thereof, from any fund or for any purpose, including amounts appropriated for judgments and all other unpaid liabilities and all other purposes for which such authorities are herein or otherwise by law required to appropriate, shall not exceed the aggregate amount available in such fund or for such purpose, as shown by the estimates of the available assets thereof at the beginning of such fiscal year and of taxes and other current revenues set forth in the budget. If the appropriations from any fund as set forth in the budget as finally adopted exceed in the aggregate the maximum amount which the board is authorized to appropriate therefrom, all appropriations made from such fund by the budget shall be void and the several amounts appropriated in the budget of the last preceding fiscal year, so far as they relate to operation and maintenance expenses, shall be deemed to be appropriated for the current fiscal year for objects and purposes, respectively, as specified in said last budget and the several amounts so appropriated shall constitute lawful appropriations for the current fiscal year, but not in excess of amounts which will enable the Board to comply with the requirements of Section 34A-402.
The board of education may amend the budget from time to time by the same procedure as is herein provided for the original adoption of the budget.
105 ILCS 5/34-47