What is the time when I can refile my 2004 US Tax Return? I wish to refile a joint return vs married filing separate - Thank you!

Call the IRS and find out if they will still allow you to Amend your 2004, form 1040.

Usually the clock expires after three years.

1. You can not amend a joint return to a married filing separte return.

2. If by amending your tax return you have a refund, you will not get it now. You must file amended return for 2004 by April 15, 2008 to get refund.

Agreed; unless you have unusual circumstances (you were ill or deployed in the military or physically unable to amend the return), it is TOO LATE to amend the return and get a refund.