Last year the IRS reported 87,000 refund checks totaling $73 million (an average of around $800 per taxpayer) were returned by the post office as undeliverable, due to unreported changes of name and/or address. In 2003, 115,744 advance child tax credit checks worth more than $50 million went undelievered.

It's important to realize undeliverable refunds are but one small component of unclaimed assets held by IRS. A significantly greater number of checks are delivered, but for one reason or another remain uncashed. Estimates of the total amount owed are in the neighborhood of $8 billion!

Regarding delivered-yet-unnegotiated checks, "Unless the taxpayer contacts the IRS, we have no way of knowing the check was not cashed." All Treasury checks now expire one year from the date of issue. If you discover an uncashed check more than a year old, you will have to apply for a replacement.

For assistance tracking down an uncashed or unpaid IRS income tax refund, go to: IRS Refund Search Note this is particularly important to heirs of deceased taxpayers, who may be owed refunds as a result of overpayments made during the year of death.