The Illinois Triennial Affidavit for Incentive Properties is a document used to verify that a property is eligible for certain incentive programs available through the state of Illinois. These incentives may include tax exemptions, abatement, credits, and other forms of financial assistance. The affidavit must be filed every three years and is used to demonstrate that the property meets all necessary requirements for the incentive program. There are three types of Illinois Triennial Affidavit for Incentive Properties: Residential, Commercial, and Industrial. The Residential Affidavit is used to verify that a residential property is eligible for a certain incentive program. The Commercial Affidavit is used to demonstrate that a commercial property is eligible for an incentive program. Finally, the Industrial Affidavit is used to verify eligibility for an incentive program for an industrial property.