30 ILCS 105/23
The item "contingencies," when used in an appropriation act, shall include expenditures for purposes either not covered in any other item or for which the amount appropriated in such other item is or becomes insufficient.
When an appropriation to any department, office or institution for any specific purpose becomes insufficient, and it is deemed necessary to expend funds out of a contingency appropriation to such department, office or institution to provide for the insufficiency, the State Comptroller may, upon approval of the Governor, transfer from such contingency appropriation to the appropriation which is or becomes insufficient, such amount as may be required; provided, that transfers to be made from appropriations to elected constitutional State officers for contingencies and transfers to be made from appropriations to the board of trustees of the University of Illinois may be made by such officers or such board of trustees without the approval of the Governor.
30 ILCS 105/23