If not submitted to NVC along with the Affidavit of Support form, the petitioner will need to provide the visa applicant with evidence of his or her domicile. Providing proof of domicile in the United States is critical for most people when submitting Form I864, Affidavit of Support.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. 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). This guide will clarify what domicile is, how to establish it, and the documentation you need for proof of domicile. Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States.