An I864 sponsor must be domiciled 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).Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States. To be considered a Texas resident for tuition purposes, students must have clearly established a domicile in Texas for the 12 months preceding enrollment. Examples of acceptable evidence. Description. Residence in the U.S.. Lease agreement; Mortgage payments; Utility bills. How Can I Prove U.S. Domicile? In this post, we'll explore examples of proof of US domicile and the documents required to establish proof of domicile. Submit an official transcript from the last U.S. high school attended.