The Illinois Affidavit of Eligibility is a document used to verify an individual's eligibility to vote in the state of Illinois. It is used to prove that the individual is a citizen of the United States, is 18 years of age or older, and is a registered voter in the state of Illinois. The affidavit is required by Illinois law and must be filled out and signed in order to cast a ballot. There are two types of Illinois Affidavit of Eligibility: the Paper Affidavit and the Online Affidavit. The Paper Affidavit must be printed out, filled out, and signed in order to be valid. The Online Affidavit must be filled out and signed electronically in order to be valid. Both types of Illinois Affidavit of Eligibility must be submitted to the local election authority in order to be valid.