On Form I864, petitioners must prove that they have the ability to financially support the visa applicant(s) if necessary. 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).In this post, we'll explore examples of proof of US domicile and the documents required to establish proof of domicile. 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. Each applicant must demonstrate the intent to reside indefinitely within the State of California and in the County of Santa Clara. Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States.