This form must accompany a bank statement or letter from the bank. 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. 864 Affidavit of support How to fill out the Form 864 immigration Tips. In this guide, we will explain who needs to complete Form I864, when to file it, and how to fill out Form I864 stepbystep. Stepbystep instructions on filling out Form I864, Affidavit of Support. 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. If there is a qualifying relative (spouse, adult child, parent, or sibling) that lives in the same household as the main sponsor, they may act as a household member that contributes income. A spouse who earns income is commonly used as a household member. For example, Jane is sponsoring her brother, Jack, but Jane's income is combined with that of her spouse, Ronald.