Must be at least 18 years old. 2. 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? In this video, we'll cover: What an affidavit of forgery is; Reasons you'd need an affidavit of forgery; and How to use an affidavit of forgery. Read more about the safety measures the SLCo's Clerk office takes to ensure the integrity and privacy of the electoral system. An affidavit is a written statement made under oath that is typically used in legal proceedings. Learn their purpose, when to use, and how to write. Salt Lake City, Utah 84114-4501.