These additional financial sponsors also have to submit an Affidavit of Support, proof of their income, and proof of their legal status in the United States. 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).On Form I864, petitioners must prove that they have the ability to financially support the visa applicant(s) if necessary. Did you get an RFE ? The address entered on the I-864 should be sufficient. Completing and signing Form I-864 makes you the sponsor. If using a joint sponsor, they'll need to fill out a separate I-864. Proof of U.S. domicile is required for the I864. Learn examples of proof of domicile along with proof of domicile documents required.