What should the letter say? I have a question about the invitation letter that is supposed to help support the B2 visa application.Comprehensive guide to writing an invitation letter for your US visa application, with free samples and tips. Invitation letters are not requested or used except as evidence that you may have help to illegally overstay your visa. The letter should include specific details like your relationship with the visitor, the purpose of their visit, duration of stay, and financial arrangements. Although not a requirement, your U.S. host can write a letter. We've provided a sample invitation letter for a B-2 visitor visa. The PAG Organizing Committee is offereing assistance if you need a Letter of Invitation to assist in your Visa Application. We have offices in countries around the world that provide visa services. See Offices outside Australia to find more information that may assist you.