Use this form to show they have adequate means of financial support and are not likely to rely on the US government for financial support. Completing and signing Form I-864 makes you the sponsor.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 guide, we will explain who needs to complete Form I864, when to file it, and how to fill out Form I864 stepbystep. This tip sheet will help you complete Form I864, Affidavit of Support Under Section 864A of the INA. Detailed Instructions for Affidavit.