In early April 2007, I filed a form 4868 (automatic 6-month extension of time to file). I knew at the time that I was due a substantial refund for 2006.

Due to some personal issues I am not going to go into here, I have organizational problems and am a late-filer. I have not yet filed my 2006 return. I'm working on it now.

4/15/2010 (this Thursday) will be three years from the original date the return was due. I am currently working on my 2006 return and it has become clear that I will not be able to collect all the data by Thursday. However I do not want to risk forfeiting my refund, which should be approximately $20,000.

Question 1. I know that a taxpayer who fails to file within three years after the due date of the return forfeits his refund. If you are a tax professional, could you tell me whether the three years are measured from the original due date, or the new due date provided six-month extension. That is, must I file by April 15, 2010, or October 15, 2010.

It probably goes without saying that, due to the amount of money at stake, I need a definite answer, not a "probably" or "I think"

Question 2. If the answer to question 1 is "the extension does not change the three-year forfeit date; you must file by 4/15," then can I file a return this Thursday and amend it a week later when I have all the data?

Thank you for your help.

Last date for filing of 2006 return to get refund was April 15, 2010.

I agree with Mukata - April 15 (today!) is the deadline for filing for a refund for tax year 2006. Unfortunately by procrastinating this long you have put yourself into a bit of a bind. I suggest that you file using the data you know, and if you must make an estimate on something make as good an estimate as you can. If you guess low, so that you have a smaller refund, then because you are past the 3 year window you won't be able to amend your return to get a bigger refund - so that will be lost money. But if you guess too high, so that you get a bigger refund now and then file an amended return later to pay some of it back, there is likely to be interest and perhaps even a penalty assessed for late payment.

The previous answers to your question are incorrect. When you have a late filed 2006 return, and have filed the 4868 extension before 4/15/2007, you have until 10/15/2010 to file that return, it doesn't change. Had you not filed the extension; 4/15/2010 would be the due date normally.

You may want to verify you have this extension as it will be recorded in IRS records. Call the IRS and ask this specific question.

This rule is found in Pub 17, under refunds for, "late filed returns".

Mack - I looked into this further, and I think you're correct, so thanks for catching this. I found in the instrctrions for Form 1040X the following:

"Generally, for a credit refund, you must file Form 1040X within three years (including extensions) after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later. If you filed your orininal return early (for example, March 1 for a calendar year return), your return is considered filed on the due date (April 15). If you had an extension to file until October 15 but you filed July 1, your return is considered filed on the extended due date (October 15)."

From this I conclude that October 15, 2010 is the deadline for the OP's filing for a refund for his 2006 return.