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. The petitioner may fill out an Affidavit of Support, Form I-134.864 Affidavit of support How to fill out the Form 864 immigration Tips. Form I-134 is a promise to financially support a person applying for a temporary visa to the United States, namely a travel visa or a K-1 fiancé visa. If you are coming to the United States on a temporary visa, you may need to prove financial support. A sponsor can file the I-134 form. The purpose of the Affidavit is to assist consular officers in determining whether a visa applicant will have adequate means of financial support in the US. In this guide, we will explain who needs to complete Form I864, when to file it, and how to fill out Form I864 stepbystep. After the appropriate form with documentation is complete, the petitioner should send it to the National Visa Center. What does the NVC do with the I-864?