The Illinois Owner Occupancy Affidavit (For Appeals Only) is a document used by an owner-occupant of a residential property who is appealing the current assessment of his or her property. The affidavit is used to verify that the property is the owner-occupant's primary residence. This document is typically used in conjunction with other documents, such as a copy of a driver's license or other proof of residence, in order to appeal the assessed value of a property. There are two types of Illinois Owner Occupancy Affidavit (For Appeals Only): 1. The Cook County Owner Occupancy Affidavit: This is an affidavit that must be completed by the owner-occupant of a property located in Cook County, Illinois. It is used to appeal the assessed value of the property. 2. The Illinois Department of Revenue Owner Occupancy Affidavit: This affidavit is used by an owner-occupant of a residential property located in any county in Illinois who is appealing the assessed value of his or her property.