We recommend completing Affidavit of Support forms on a computer or typewriter, with answers typed in CAPITAL letters. Providing proof of domicile in the United States is critical for most people when submitting Form I864, Affidavit of Support.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). If both beneficiary and sponsor are living abroad, you'll need to supply evidence of U.S. domicile with your Form I-864. This guide will clarify what domicile is, how to establish it, and the documentation you need for proof of domicile. Line-by-line guidance for properly filling out USCIS's I-864 Affidavit of Support to sponsor an immigrating family member. I am household member and filled form 1864A and added as a household member i was asked to provide proof of citizenship and proof of domicile. Students in this category must complete an Affidavit.