You can normally only go back three years for a refund, with extensions. The statue of limitations is three years after the return is due or filed. So, if you get an extension to file, you can take the three years from the extension.
so really the dead line for filing a 2004 return is as follows:
1. First filing is april 15th, 2005 unless you had an extension.
2. Limitations on getting a refund generally would be 15 April 2008 or if you had an extension 3 years plus six months.
If you do not file, you can not get the refund, right.
The statue is complicated and the rules for counting the time highly circumstantial. If in doubt, file.
So you have an automatic extension while overseas, and that means you have until the end of teh 3 years following June 15th, anyway.
Please not, you can not take the credit for the foreign earned income exclusion unless you file. So, if you do not file, and the IRS knows you earned the money, then they can assess taxes as if there were no foreign earned income. You need to file anyway to enarue you do not have a tax debt, regardless if you have a refund coming as a result of the statute of limitations for refunds.