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). For the typical sponsor who has always lived in the United States, no special evidence is required to prove domicile.I never heard of sending a joint sponsor's drivers license in with an I864. I'm talking about proof of Us domicile for Joint sponsor. Examples of proof that a sponsor's trip abroad is temporary and that he or she has maintained a domicile in the United States may include:. To be an I864 sponsor, you must be "domiciled" in the United States, among other things. Completing and signing Form I-864 makes you the sponsor. In today's video we are going to be filling out form i 864 the affidavit of support form for the joint sponsor.