The IRS has issued a Tax Guide for U.S. Citizens and Resident Aliens Abroad, with all the basics you should need for filing your 2015 return.
(Remember that U.S. citizens and resident aliens are responsible for reporting their worldwide income and that very specific rules apply to filing from abroad. You may need professional advice but you can at least begin your task by looking at the IRS Guide.)
With the last overseas IRS offices now closed, this may be the best place to start and can serve as a basic reference for this tax filing season, telling you:
Who must file
What you must report
When you should do it
Where you should file
How to go about it
(the "Why" is not included...)
Overseas filers should go to the very end of the section on "How to get tax help" for the appropriate phone number (English only, non toll-free) and mailing address. If you are unable to reach or get the information you need from the IRS, the National Taxpayer Advocate Service (contact information in the same section) is your best friend at the IRS!
The Tax Guide is available as a downloadable PDF file.
