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 I864 Affidavit of Support is a signed document that a sponsor signs in order to accept full financial responsibility for the sponsored immigrant.This tip sheet will help you complete Form I864, Affidavit of Support Under Section 864A of the INA. Detailed Instructions for Affidavit. Who Should Fill Out Form I-134 Affidavit of Support? This tip sheet will help you complete Form I864EZ, Affidavit of Support Under Section 864A of the INA. Detailed Instructions for Filing. The petitioning sponsor is the relative who filed the immigrant visa petition on behalf of the intending immigrant. Note: Mistakes in completing the I-864 are a common reason for delays with an immigrant visa application. A letter of invitation or Affidavit of Support is not needed to apply for a nonimmigrant tourist visa.