What Documents Do I Need to Show That I'm a United States Citizen?
A copy of your valid, unexpired U.S. passport that was issued for at least five years. You must submit copies of all pages in the passport.
If you dont have it, you can submit one of the following documents:
If you were born in the United States, a copy, front and back, of your birth certificate, or
If you were naturalized, a copy, front and back, of your original Certificate of Naturalization, or
If you were born outside the United States, and you are a U.S. citizen through your parents, submit either your original Certificate of Citizenship or Your Form FS-240 (Report of Birth Abroad of a United States Citizen)