65 ILCS 5/8-2-9
In municipalities with less than 500,000 inhabitants, except as otherwise provided in this Section, the corporate authorities shall pass an ordinance within the first quarter of each fiscal year, to be termed the annual appropriation ordinance. On and after January 1, 2020, if a disaster, state of emergency, or national emergency is declared within the 60 days preceding the end of the first quarter of a municipality's fiscal year and the disaster, emergency, or declaration impacts the municipality, the time limit to pass the annual appropriation ordinance shall be extended for the duration of the disaster or emergency and for 60 days thereafter. During the extended period, the municipality may expend sums of money up to amounts budgeted or appropriated for those objects and purposes in the previous fiscal year to defray all necessary expenses and liabilities of the municipality. In this ordinance, the corporate authorities (i) may appropriate sums of money deemed necessary to defray all necessary expenses and liabilities of the municipalities, including the amounts to be deposited in the reserves provided for in the Illinois Pension Code and (ii) shall specify the objects and purposes for which these appropriations are made and the amount appropriated for each object or purpose. Among the objects and purposes specified shall be the reserves provided for in the Illinois Pension Code. Except as otherwise provided, no further appropriations shall be made at any other time within the same fiscal year, unless a proposition to make each additional appropriation has been first sanctioned by a petition signed by electors of the municipality numbering more than 50% of the number of votes cast for the candidates for mayor or president at the last preceding general municipal election at which a mayor or president was elected, by a petition signed by them, or by a majority of those voting on the question at a regular election or at an emergency referendum authorized in accordance with the general election law. The corporate authorities may by ordinance initiate the submission of the proposition. During any fiscal year, the corporate authorities in municipalities subject to this Section may adopt a supplemental appropriation ordinance in an amount not in excess of the aggregate of any additional revenue available to the municipality, or estimated to be received by the municipality after the adoption of the annual appropriation ordinance for that fiscal year, or from fund balances available when the annual appropriation ordinance was adopted but that were not appropriated at that time. The provisions of this Section prohibiting further appropriations without sanction by petition or election shall not be applicable to the supplemental appropriation for that fiscal year. The corporate authorities at any time, however, by a two-thirds vote of all the members of the body, may make transfers within any department or other separate agency of the municipal government of sums of money appropriated for one corporate object or purpose to another corporate object or purpose, but no appropriation for any object or purpose shall thereby be reduced below an amount sufficient to cover all obligations incurred or to be incurred against the appropriation. Nothing in this Section shall deprive the corporate authorities of the power to provide for and cause to be paid from the funds of the municipality any charge imposed by law without the action of the corporate authorities, the payment of which is ordered by a court of competent jurisdiction.
At least 10 days before the adoption of the annual appropriation ordinance, the corporate authorities of municipalities over 2,000 in population shall make the proposed appropriation ordinance or a formally prepared appropriation or budget document upon which the annual appropriation ordinance will be based conveniently available to public inspection. In addition, the corporate authorities shall hold at least one public hearing on that proposed appropriation ordinance. Notice of this hearing shall be given publication in one or more newspapers published in the municipality or, if there is none published in the municipality, in a newspaper published in the county and having general circulation in the municipality at least 10 days before the time of the public hearing. The notice shall state the time and place of the hearing and the place where copies of the proposed appropriation ordinance or formally prepared appropriation or budget document will be accessible for examination. The annual appropriation ordinance may be adopted at the same meeting at which the public hearing is held or at any time after that public hearing.
After the public hearing and before final action is taken on the appropriation ordinance, the corporate authorities may revise, alter, increase, or decrease the items contained in the ordinance.
Notwithstanding any above provision of this Section, any municipality in which Article 5 becomes effective after the annual appropriation ordinance has been passed for the current fiscal year may amend the appropriation ordinance in any manner necessary to make Article 5 fully operative in that municipality for that fiscal year. No amendment shall be construed, however, to affect any tax levy made on the basis of the original appropriation ordinance.
This Section does not apply to municipalities operating under special charters.
65 ILCS 5/8-2-9