75 ILCS 5/4-15

Appropriations for library purposes within the annual appropriation ordinance of the corporate authority, shall terminate with the close of the fiscal year of the library, except that any remaining balances shall be available for 90 days thereafter for the authorization of the payment and the payment of obligations incurred either before the close of the fiscal year or within the 90-day period thereafter. All balances remaining after such 90-day period shall be available for transfer to be accumulated under Sections 5-1 and 5-8 of this Act.