If you are applying for a K1 Visa you would need certain documents to prove not only that you are an American but also to prove that you are able to support your fiancee in the United States. The documents needed for most K-1 Visa applications are listed below. These are not a full list of documents and you might require additional documents so always speak to an immigration attorney with regards to any documents you may need for your K-1 Visa application.