Living outside the US? Lucky you - you get an automatic two month extension of time to file your income tax return, and also the time to pay if you owe additional tax after finishing up your return. For filers who use the calendar year as their tax return (that is pretty much all of us), this gives you until 15 June 2012 to complete your return and submit payment.
There is no form to fill out. I'm conflicted about whether it is helpful to file an official extension if you don't have to file. One year that my husband was in a combat zone, my accountant file an extension. Well, our real filing date was wwaayy after the extension expired, and the IRS got all excited about the fact that we hadn't filed by the day specified on the extension. It wouldn't have been a problem had there been no extension. So you see, I'm not really sure if filing an extension is a good thing or a bad thing.
If you need more information about federal income tax rules and military service, you will probably find most of your answers in IRS Publication 3, The Armed Forces Tax Guide. If your answer isn't there, I've found that the search engine on the IRS website is great! Good luck to all my tax return preparing friends everywhere.