I am sponsoring the following family members immigrating at the same time or within six months of the principal immigrant named in Part 3. 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.Line-by-line guidance for properly filling out USCIS's I-864 Affidavit of Support to sponsor an immigrating family member. An Affidavit of Support is US Immigration Form I-864. The process of establishing someone as your financial sponsor begins with completing and filing the form i-864 after debit of support. The joint sponsor must also submit Form I864 and meet the income requirements. You, the sponsor (petitioner), and the joint sponsor must complete Form I-864. See tips for completing Form I-864. The person who signs the Affidavit of Support is also called the "sponsor. The petitioner in question must fill out Form I-864 Affidavit of Support when petitioning and sponsoring an immigrant.