Instructions: Heading: Enter your state. Next enter the County that you reside in.A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court. 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. The notary shall record the transaction in his or her journal and fill out the journal with the signer's satisfactory evidence of identity. Affidavit definition: . See examples of AFFIDAVIT used in a sentence. I'm going to be walking through the steps of what an off-date financial information is and how to properly fill out this form.