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). Driver's License or State ID: As it shows your permanent residence, a valid U.S. driver's license can act as proof of domicile.How Can I Prove U.S. Domicile? Learn the what, why, and how of filing a form I-864 affidavit of support for US immigration.