Students in this category must complete an Affidavit. The U.S. citizen uses this form to promise the government that they will be able to financially support the foreign national beneficiary.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). On Form I864, petitioners must prove that they have the ability to financially support the visa applicant(s) if necessary. U.S. citizens and green card holders sponsoring family members must present proof of domicile according to the National Visa Center (NVC). If both beneficiary and sponsor are living abroad, you'll need to supply evidence of U.S. domicile with your Form I-864. Instead, submit a photocopy of these documents to NVC. However, you must bring these original documents to your visa interview.