(MONEY Magazine) – As you organize your 1993 tax records this month, take a moment to think whether you might have failed to collect your '92 federal income tax refund. Incredibly, some 96,000 taxpayers never got their IRS refund checks last year. They're owed a staggering $50 million -- an average of $521 a person. IRS spokesman Gail Ellis explains that the Postal Service returned the checks as undeliverable. The most common explanations: The address was wrong or the person had moved without leaving a forwarding address. If you haven't received your refund check, it's up to you to holler. You can do so by calling the IRS at 800-829-1040, or by writing or visiting your local IRS office; assuming you are owed money, you should receive it within six weeks. If you've moved since filing your return, however, you will have to send the IRS Form 8822, the official change-of-address notification. Don't limit yourself to tracking down ; a '92 refund. The government has another $44 million in unclaimed refunds from '91, $25 million from '90 and varying amounts from earlier years. In fact, says the IRS, there's no statute of limitations on how far back a claim can go.