If you are a U.S. citizen or resident alien, the rules for filing income, estate, and gift tax returns and paying estimated tax are generally the same whether you are in the United States or abroad. Your worldwide income is subject to U.S. income tax, regardless of where you reside. 

When to File 

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. 

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 

USA