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). Applicants should take to the visa interview clear, legible photocopies of civil documents and translations, such as birth and divorce certificates.This guide will explain how to prove domicile when filling out Form I-864 ("Affidavit of Support"). Consular processing support without the high price tag. Upload the most recent version of Form I864 on USCIS website. Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States. Providing proof of domicile in the United States is critical for most people when submitting Form I864, Affidavit of Support. A citizen of a foreign country who seeks to travel to the U.S. generally must first obtain a U.S. visa, which is placed in the traveler's passport.