Completing and signing Form I-864 makes you the sponsor. One form of substitute document that you might need to use is what's called a "sworn declaration.We all live in the same house and I am witness to a genuine martial relationship. Sworn Statement: While a notarization is not required, the affidavit should include a sworn statement. Common Mistakes to Avoid. Many websites offering immigration resources provide sample affidavits. In many communities, notaries are scarce or inaccessible for those with limited financial resources.