"Does the Internal Revenue Service (IRS) owe you money? Currently, the IRS owes refund checks worth a total of more than $103 million to more than 104,000 Americans. And it owes stimulus checks worth a total of about $163 million to about 279,000 people."
Mainly, people have moved and have, for some strange reason, forgotten to tell the IRS! You can use this link to see if you are due a check from the IRS!