In California, about 154,500 people are owed a median refund of $537 (half can expect more, and half less), while in Texas, 103,000 taxpayers are owed a median of $624.

A state-by-state breakdown of estimates for individuals who failed to file a 2005 return with a refund due is below.

If you didn’t file a 2005 return, consider doing so soon: The deadline for claiming a refund for that tax year is April 15 this year, and you must file a return to get a refund. After that deadline, any unpaid refunds for 2005 are handed over to the U.S. Treasury. You will lose your tax refund if you do not file within 3 years of the due date of the tax return.

There is no penalty for filing a late return if you have a refund coming to you. However, to be eligible for a refund for 2005, you must also file your 2006 and 2007 returns as well. And, if you have any outstanding taxes owed or other federal debt, such as student loans, the IRS will apply the refund to that debt before sending any money to you.

It’s not always taxpayers with big tax bills that don’t file returns. Many people decide not to file if their income falls below the filing threshold. And many low-income workers may stand to lose more than their refunds, including those who may not have claimed the Earned Income Tax Credit (EITC). Generally, unmarried individuals qualified for the EITC if in 2005 they earned less than $35,263 and had more than one qualifying child living with them, earned less than $31,030 with one qualifying child, or earned less than $11,750 and had no qualifying child.

Current and prior year tax forms and instructions are available on the Forms and Publications page IRS we site or by calling 1-800-TAX-FORM (1-800-829-3676).

If you need help filing your back taxes, visit the Tax Resolution Services web site for a free tax relief consultation or call 866-IRS-PROBLEMS.