Forget about your 2009 tax return for a minute. If you didn’t file one for 2006, you might be missing out on some money from back then. But you’re quickly running out of time to claim it.

Three years ago, more than 1.4 million individuals apparently decided they had better things to do than file their 2006 tax returns, even though they were due refunds. In total, more than $1.3 billion worth of refunds from that tax year is still sitting in the Internal Revenue Service account.

Taxpayers can still get their old refund checks, which the IRS says could amount to more than $800 for some folks. But the claim, via a 2006 Form 1040, must be made by April 15. After that, the federally allowed three-year window of opportunity from the original filing deadline, which was April 2006, closes forever and Uncle Sam gets to keep the cash.

If you think some of the refund stash is yours, you can download a 2006 Form 1040 from the IRS Web site. If you need an old 1040A or 1040EZ instead, you can find them at the agency’s index of past-year forms.

–> http://www.irs.gov/formspubs/article/0,,…

Be sure to check out the 2007 and 2008 documents, too, if you didn’t file a return for those years either. The IRS won’t send you your 2006 cash unless you filed in subsequent years.

And you’d better do it soon. After April 15, your refund money stays in Uncle Sam’s pocket.