The account holder MUST provide an Affidavit of Forgery before any criminal charges can be filed! An affidavit must accompany each forged or counterfeited item.This affidavit is made voluntarily for the purpose of establishing the fact that my item was altered. This affidavit is made voluntarily for the purpose of establishing the fact that my signature is a forgery. 7. Do you know who forged your signatures? The Affidavit of Check Fraud form is used to make a legal claim about the wrongful use of a negotiable instrument. When. Vendor must complete, sign, and notarize the "Affidavit of Fraudulent Activity" form on the following page. Important: The person alleging forgery must complete this form in longhand. This affidavit is made voluntarily and for the purpose of establishing the claim of forgery. This document is an affidavit used to report issues with a check.