20 ILCS 3005/6.01
The several courts of the State, the General Assembly, its committees and commissions, and the elective officers in the Executive department shall file with the Office information which will enable the Governor to present to the General Assembly estimates of the amount of money required to be raised by taxation for all purposes. They shall submit to the Office, on forms prescribed by the Office, information as to the revenues and expenditures for the preceding fiscal year, the appropriations made by the General Assembly for the preceding fiscal year, the expenditures therefrom, obligations incurred thereon, and the amounts unobligated and unexpended, an estimate of the revenues and expenditures of the current fiscal year, and an estimate of the revenues and amounts needed for the respective departments and offices for the next succeeding fiscal year.
20 ILCS 3005/6.01