30 ILCS 330/15
On or before the last day of each month the State Treasurer and Comptroller shall transfer from (1) the Road Fund with respect to Bonds issued under paragraphs (a) and (e) of Section 4 of this Act, or Bonds issued under authorization in Public Act 98-781, or Bonds issued for the purpose of refunding such bonds, and from (2) the General Revenue Fund, with respect to all other Bonds issued under this Act, to the General Obligation Bond Retirement and Interest Fund an amount sufficient to pay the aggregate of the principal of, interest on, and premium, if any, on Bonds payable, by their terms on the next payment date divided by the number of full calendar months between the date of such Bonds and the first such payment date, and thereafter, divided by the number of months between each succeeding payment date after the first. Such computations and transfers shall be made for each series of Bonds issued and delivered. Interest payable on variable rate bonds shall be calculated at the maximum rate of interest that may be payable for the relevant period, after taking into account any credits permitted in the related indenture or other instrument against the amount of such interest required to be appropriated for such period pursuant to subsection (c) of Section 14 of this Act. Computations of interest shall include the amounts certified by the Director of the Governor's Office of Management and Budget under subsection (b) of Section 9 of this Act. Interest for which moneys have already been deposited into the capitalized interest account within the General Obligation Bond Retirement and Interest Fund shall not be included in the calculation of the amounts to be transferred under this subsection. Notwithstanding any other provision in this Section, the transfer provisions provided in this paragraph shall not apply to transfers made in fiscal year 2010 or fiscal year 2011 with respect to Bonds issued in fiscal year 2010 or fiscal year 2011 pursuant to Section 7.2 of this Act. In the case of transfers made in fiscal year 2010 or fiscal year 2011 with respect to the Bonds issued in fiscal year 2010 or fiscal year 2011 pursuant to Section 7.2 of this Act, on or before the 15th day of the month prior to the required debt service payment, the State Treasurer and Comptroller shall transfer from the General Revenue Fund to the General Obligation Bond Retirement and Interest Fund an amount sufficient to pay the aggregate of the principal of, interest on, and premium, if any, on the Bonds payable in that next month.
The transfer of monies herein and above directed is not required if monies in the General Obligation Bond Retirement and Interest Fund are more than the amount otherwise to be transferred as herein above provided, and if the Governor or his authorized representative notifies the State Treasurer and Comptroller of such fact in writing.
30 ILCS 330/15