30 ILCS 105/9.05

In the event that a voucher is submitted for advance payment of goods or services, the certification prescribed by Section 9.04 shall be made. In addition, the voucher shall state on its face that the goods or services are being procured pursuant to a formal, written contract the terms of which require advance payment. If it is not possible to execute a written contract, the voucher shall so state. The voucher shall also state that the contract requires the goods or services to be delivered or received prior to the expiration of the lapse period of the fiscal year to which the expenditures are charged, provided however, that such a statement shall not be required on vouchers submitted for periodical subscriptions or organizational memberships.