55 ILCS 5/6-1001
In all counties not required by law to pass an annual appropriation bill within the first quarter of the fiscal year, the county board or board of county commissioners, as the case may be, shall adopt each year an annual budget under the terms of this Division for the succeeding fiscal year. Such budget shall be prepared by some person or persons designated by the county board and such budget shall be made conveniently available to public inspection and provided to the public at a public meeting at least fifteen days prior to final action thereon except that nothing in this Act shall restrict a county board or board of county commissioners from acting at a public meeting to amend a budget after making that budget available to the public and prior to final adoption. Notices pertaining to the meeting and the proposed budget shall be posted on the county's website, if it maintains one. If a county does not maintain a website, then the county shall comply with the Open Meetings Act in giving notice of such agenda items and make the proposed budget available for public inspection. The vote on such budget shall be taken by ayes and nays and entered on the record of the meeting. The annual budget adopted under this Act shall cover such a fiscal period of one year to be determined by the county board of each county except as hereinafter provided and all appropriations made therein shall terminate with the close of said fiscal period except as hereinafter provided, provided, however, that any remaining balances shall be available until 30 days after the close of the fiscal year in counties with a population of less than 100,000, and until 90 days after the close of the fiscal year in counties with a population of more than 100,000 but less than 3,000,000 inhabitants, only for the authorization of the payment of obligations incurred prior to the close of said fiscal period. Any county which determines to change its fiscal year may adopt a budget to cover such period greater or less than a year as may be necessary to effect such change and appropriations made therein shall terminate with the close of such period.
55 ILCS 5/6-1001