In an article on MSN Money, MarketWatch reported that about $1.2 billion is sitting in the IRS coffers—waiting to be claimed by taxpayers. The money belongs to taxpayers who neglected to file a 2004 tax return. The average return for taxpayers who didn’t file in 2004 is $552.

This is significant this tax season because if some of this money belongs to you, the clock is ticking. If you don’t file your 2004 return by April 15th this year, the funds will be turned over to the U.S. Treasury.

There is no penalty for filing a late return as long as the IRS owes you money; however, if you’re eligible for a 2004 refund, you’ll have to file your 2005 and 2006 returns as well.

You can access forms for prior years at IRS.gov on the forms and publications page. Or, call 800-TAX-FORM. Read the full article on MSN here.