Typically, in order to claim US domicile, the Affidavit of Support sponsor must be residing in the United States. This guide will clarify what domicile is, how to establish it, and the documentation you need for proof of domicile.You should submit evidence to the National Visa Center along with Form I-864. 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). One of the requirements for Form I864 is showing that you are domiciled in the US. In other words, your principal residence must be located in the US. There are several requirements to submit an I864 Affidavit of Support. The proof of U.S. domicile is one of those required documents.