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. If you have a joint sponsor, they must also complete Form I864.In today's video we are going to be filling out form i 864 the affidavit of support form for the joint sponsor. An Affidavit of Support sponsor must be at least 18 years old and must be either a U.S. citizen or a lawful permanent resident. This form is required in most familybased green card applications, including CR1 and IR1 spouse visas and some employmentbased green card applications. In order to act as a sponsor, an individual must file a Form I-864, Affidavit of Support. Situations Where Sponsor is not Required. If you are filing Form I864 as the petitioning sponsor, use our How to Fill Out Affidavit of Support Form I864 guide. If you are filing Form I864 as the petitioning sponsor, use our How to Fill Out Affidavit of Support Form I864 guide. An affidavit of support, also referred to as Form I864, is a document that assigns the financial responsibility of the applicant to someone in their life.