235 ILCS 5/6-10
It shall be the duty of every retail licensee to make books and records available upon reasonable notice for the purpose of investigation and control by the Illinois Liquor Control Commission or any local liquor control commission having jurisdiction over the licensee. Such books and records need not be maintained on the licensed premises, but must be maintained in the State of Illinois; however, if access is available electronically, the books and records may be maintained out of state. However, all original invoices or copies thereof covering purchases of alcoholic liquor must be retained on the licensed premises for a period of 90 days after such purchase, unless the Commission has granted a waiver in response to a written request in cases where records are kept at a central business location within the State of Illinois or in cases where books and records that are available electronically are maintained out of state.
235 ILCS 5/6-10