Two groups get extra time without asking: US citizens and residents who live and work outside the country, and service members in a combat zone. The rules are different and they stack differently.
Living abroad: two automatic months
If on April 15 you live outside the United States and Puerto Rico and your main place of business or duty post is outside, your return and payment are due June 15. You do not file anything to get it; you attach a statement to the return saying you qualify. Interest still runs from April 15 on any unpaid tax, but the failure-to-pay penalty does not start until June 15.
If June is not enough, file Form 4868 by June 15 and check the box on line 8. That gives you until October 15. Beyond that, a written request for a discretionary two-month extension to December 15 is possible, and taxpayers waiting to qualify for the foreign earned income exclusion can use Form 2350.
Combat zone: the clock stops
Service members and support personnel in a designated combat zone (and their spouses) get the filing and payment deadlines suspended for the entire time they are in the zone, plus 180 days after they leave, plus the number of days that were left in the filing season when they entered. Interest and penalties are suspended too. Hospitalization from zone injuries extends it further.
Nothing has to be filed to get this. The IRS asks that you write the zone designation at the top of the return, and it helps to notify the IRS by email if a notice arrives anyway.
Common mistake
Someone stationed overseas but not in a combat zone assuming the combat zone rules apply. They get the two-month abroad extension, not the suspension.
Ready to file it?
You can file a personal extension (Form 4868) online in a few minutes with TaxExtension.com, an IRS-authorized e-file provider operated by our publisher. The extension is automatic; the payment is still due on the original date.