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. You, the sponsor (petitioner), and the joint sponsor must complete Form I-864.See tips for completing Form I-864. Completing and signing Form I-864 makes you the sponsor. In today's video we are going to be filling out form i 864 the affidavit of support form for the joint sponsor. In this guide, we will explain who needs to complete Form I864, when to file it, and how to fill out Form I864 stepbystep. The "Affidavit of Support" is a signed document to accept financial responsibility for a family member who is seeking a green card. Form I-864 is required for most family-based immigrants and some employment-based immigrants to show that they have adequate means of financial support. This video will help you to fill out I-864 For Joint Sponsor. If you are filing Form I864 as the petitioning sponsor, use our How to Fill Out Affidavit of Support Form I864 guide.