30 ILCS 390/12
Upon each delivery of Bonds authorized to be issued under this Act, the Comptroller shall compute and certify to the State Treasurer the total amount of principal of and interest on the Bonds issued that will be payable in order to retire such Bonds and the amount of principal of and interest on such Bonds that will be payable on each payment date according to the tenure of such Bonds during the then current and each succeeding fiscal year. On or before the last day of the month preceding each payment date, the Treasurer and the Comptroller shall transfer from the General Revenue Fund in the State Treasury to the School Construction Bond Retirement and Interest Fund a sum of money, appropriated for such purpose, so such Fund contains an amount equal to the aggregate of the amount of principal of and interest on the Bonds payable by the terms of the Bonds on the next payment date. Such computations and transfers shall be made for each series of the Bonds issued and delivered. The transfer of monies herein above directed is not required if monies in the School Construction Bond Retirement and Interest Fund received from other sources are more than the amount otherwise to be transferred as hereinabove provided, and if the Governor notifies the Comptroller and the Treasurer of such fact.
30 ILCS 390/12