In New York, the application for a marriage license is not merely a form like any other, it is an affidavit. 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. DC-430 File with a verified complaint to request the court to issue a summons if you do not have an attorney. Affidavit of Personal Service DC-149R. An affidavit is a sworn statement of fact that can be used in a variety of legal proceedings, from bankruptcy cases to family and civil litigation matters.