Who Must File?
All U.S. citizens and resident aliens must file a U.S. individual income tax return, even if they permanently live outside the United States and may not owe any tax because of income exclusion or tax credit.
When to File
The due date for filing your return is April 15. When the due date falls on a Saturday, Sunday, or a legal U. S. holiday, the due date is delayed until the next business day. (If you file on a fiscal year basis, the due date is 3 months and 15 days after the close of your fiscal year.)
If you are a U.S. citizen or resident alien residing overseas or are in the military on duty outside the U.S. on the regular due date of your return, you are allowed an automatic 2-month extension to file your return without requesting an extension. For a calendar year return, the automatic 2-month extension is to June 15. Note that you must pay any tax due by April 15 or interest will be charged starting from April 15. See the IRS website on how to file for further extensions.
Where to File
If you are a U.S. citizen or resident alien (including a green card holder) and you live in a foreign country, mail your U.S. tax return to:
Department of the Treasury
Internal Revenue Service Center
Austin, TX 73301-0215
You can mail your tax return and payment using the postal service or approved private delivery services. A list of approved delivery services is available from the IRS. If you mail a return from outside the United States, the date of filing is the postmark date. However, if you mail a payment, separately or with your return, your payment is not considered received until the date of actual receipt.
Electronic Filing (e-file)
There are a few options for electronic filing.. Taxpayers with an AGI (Adjusted Gross Income) within a specified threshold can electronically file their tax return for free using Free File. Taxpayers with an AGI greater than the specified threshold can either use the Free File Fillable Forms or e-file by purchasing commercial software. A limited number of companies provide software that can accommodate foreign addresses. The IRS website provides some help in choosing an e-file service.