Taxpayers who live outside the U.S. and Puerto Rico and whose main place of work is outside the U.S. and Puerto Rico already have an automatic 2-month filing extension. See the IRS Instructions for Form 4868 for more information.
You must attach a statement to your return explaining that you qualify for the automatic extension:
Taxpayers in military service on duty outside the U.S should refer to IRS Publication 3 Armed Forces' Tax Guide for guidelines for the extension deadline.
If you qualify for the automatic 2-month extension but would like to request an additional four months by filing Form 4868, see Filing an Extension - Form 4868. To indicate that you are out of the country, check the box on the screen titled Form 4868 - Out of the Country. For this screen to appear, the date entered for Today's Date must be 4/19/2017 or later.