Line-by-line guidance for properly filling out USCIS's I-864 Affidavit of Support to sponsor an immigrating family member. Completing and signing Form I-864 makes you the sponsor.This tip sheet will help you complete Form I864, Affidavit of Support Under Section 864A of the INA. Detailed Instructions for Affidavit. The purpose of the Affidavit is to assist consular officers in determining whether a visa applicant will have adequate means of financial support in the US. In this video I will guide you through parts of the Affidavit of Support form that are important for sponsors who file taxes jointly. Note: Mistakes in completing the I-864 are a common reason for delays with an immigrant visa application. The National Visa Center (NVC) processes immigrant visa petitions after the U.S. Citizenship and. However, an intending immigrant whose income is being used to meet the income requirement does not need to complete. The person completing and signing this affidavit is the sponsor.