The Cook County Clerk's office is the official record keeper for marriages, civil unions and domestic partnerships in Chicago and suburban Cook County. The bride and bride-groom, along-with the three witnesses are required to be present and sign before the Consular Officer for the registration of the marriage.Fill out and sign a marriage license application. Fill out and sign the marriage license application. Forms must be completely filled out in black ink, signed, and notarized. View age and identification requirements, fee information, and how to apply for a license or copies of a license. Fill out the Clerk's Online Marriage Application. In addition to the application form, you will need to provide your current U.S. passport and a certified copy of your marriage certificate. The Cook County Clerk's office serves as the official record keeper for births, marriages and deaths that occur in Chicago and suburban Cook County. Illinois marriage law does not require minister registration, and no office dedicated to filing ministry credentials.