Line-by-line guidance for properly filling out USCIS's I-864 Affidavit of Support to sponsor an immigrating family member. 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.864 Affidavit of support How to fill out the Form 864 immigration Tips US mmigration with Attorney Jacob Sapochnick 1 fiancee visa couple must complete both the I134 and the I864 forms. However, the forms are not filed together. Many embassies may also require the declaration for K1 fiancé visa applicants. Which one we have to fill out for K1 visa? Immigration officials may request the I-134 declaration at the time of the K-1 application. If you have a joint sponsor, the joint sponsor must also complete USCIS Form I-864, not Form I-864A. After filing Form I129F: Petition for Alien Fiancé and Form DS160: Online Nonimmigrant Visa Application, you will attend a visa interview.