Proof of Departure
If you have not booked a flight and cannot do so until the last minute, you can submit a business letter explaining the circumstances. The letter should be on company letterhead, signed by an official in your company other than yourself. The letter should state the purpose of your trip, where you are traveling, explain why you are not able to provide an itinerary, and give the earliest date by which you must have your passport. You are allowed to submit a photocopy or fax of this letter.