65 ILCS 5/8-2-7
Except as otherwise specially provided by law, no further appropriations in municipalities specified in Section 8-2-1 shall be made prior to the passage of the next succeeding annual appropriation ordinance. However, during any fiscal year the corporate authorities in such municipalities 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 subsequent to the adoption of the annual appropriation ordinance for that fiscal year. Such supplemental appropriation ordinance shall only affect revenue that was not available for appropriation when that annual appropriation ordinance was adopted, and the provisions of Section 8-2-6 relating to publication, notice and public hearing shall not be applicable to such supplemental appropriation ordinance or to the budget document forming the basis of such ordinance. At any time during the fiscal year, the corporate authorities by a majority vote of all their members and upon request of the mayor, 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 the aggregate of transfers from any appropriation shall not exceed 5% of the appropriation. At any time after the first half of each fiscal year, the corporate authorities may, by a two-thirds vote of all of their members, 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 in excess of the 5% limitation, but no appropriation for any object or purpose shall by virtue of any transfer herein authorized be reduced below an amount sufficient to cover all obligations incurred or to be incurred against that appropriation.
65 ILCS 5/8-2-7