International Tax Gap Series Before leaving the United States or any of its possessions permanently or for an extended amount of time, all U.S. resident aliens and nonresident aliens (with certain exceptions) must prove they have met all federal tax requirements. This is done by obtaining a tax clearance document, commonly called a “sailing permit” or “departure permit”, from the IRS. Refer to the IRS Departing Alien Clearance (Sailing Permit) page for more details regarding this requirement. References and Links Tax Assistance Center Locations Form 1040-C, U.S. Departing Alien Income Tax Return Form 2063, U.S. Departing Alien Income Tax Statement Publication 519, U.S. Tax Guide for Aliens Return to: The International Tax Gap Series