Proof of U.S. domicile is required for the I864. Learn examples of proof of domicile along with proof of domicile documents required.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). You must submit documentation to prove your allegation of absence from the US as the reason a Social Security Number was never assigned. Each civil document (birth certificate, marriage certificate, police certificate, etc.) must strictly meet the Department of State (DOS) requirements. Instructions to Applicants to the M.D. program: This is a fillable PDF form. Please answer the following questions within the space.