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). Purpose: To request domicile verification from a nonrelative who is familiar with the household's situation.Providing proof of domicile in the United States is critical for most people when submitting Form I864, Affidavit of Support. Did you get an RFE ? The address entered on the I-864 should be sufficient. The applicant must use this affidavit to support their claim of residency or being domiciled in Texas.