Providing proof of domicile in the United States is critical for most people when submitting Form I864, Affidavit of Support. 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).2 form; o SSA1099 form; o Non SSA1099 form; o Pay stub showing the applicant's name and full social security number; or. •. How Can I Prove U.S. Domicile? Before you can turn in your Utah residency form, you must live in Utah for 12 or more continuous months. Proof of physical presence records MUST have all 3 of the following on them: Student's name; Exact dates; Proof of an event happening in Utah.