This guide will clarify what domicile is, how to establish it, and the documentation you need for proof of domicile. How Can I Prove U.S. Domicile?Washington State offers specific templates designed to simplify the process for legally domiciled adults. If you want to sponsor someone for a family-based green card, you need to provide proof of a U.S. domicile in your Affidavit of Support (Form I-864). Directions: Please print clearly and answer each question. Incomplete or illegible forms cannot be considered and will be returned. Use our Affidavit of Residency form to verify your home address for official purposes. On Form I864, petitioners must prove that they have the ability to financially support the visa applicant(s) if necessary. All domicile must be established at least one year immediately prior to the first day of the quarter the student is seeking residency. You must provide proof of citizenship or lawful residency to apply for, renew, or transfer a driver license (CDL) or commercial learner permit (CLP).