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). How Can I Prove U.S. Domicile?These documents collectively help establish that your permanent home is in the U.S., meeting the domicile requirement for immigration purposes. In this post, we'll explore examples of proof of US domicile and the documents required to establish proof of domicile. Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States. Please submit proof of domicile.