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. Fill Out the Form I129.If you met your fiancé(e) or spouse through the services of an international marriage broker, you must notify USCIS. The co-sponsor must submit their own Affidavit of Support (Form I-864) and must meet the above income requirements all on their own. Do not require a copy of the Affidavit of Suport or verification of sponsor income or assets. Even if you don't have sufficient income, sponsors are required to prepare Form I864, Affidavit of Support. Needed to calculate child support. Filling Out the Financial Affidavit Form. The U.S. citizen fiancé must provide Form I-134, also known as the Affidavit of Support, as part of the K-1 visa process. The persons described in number 2 and 3 of the above.