The IRS is looking to get in contact with thousands of people after mailing address validation
errors meant that thousands of refund checks were returned.
Several states, including Massachusetts, Iowa and Florida are affected as the tax agency attempts to refund a nationwide total of $123.5 million to 107,831 people.
In Florida, where more than 10,000 people are owed roughly $15 million in refunds, IRS spokesman Mike Dobzinski said that the state's "average undeliverable refund is $1,538".
He added: "We'd like to get this money back to taxpayers as quickly as possible. All we need is an updated address and we can reissue the check."
The IRS said that many checks are often returned due to problems with address verification
and said that those who think they have been affected should contact the tax office immediately.
Mr Dobzinski also advised that taxpayers who are intending to move address should always contact their local USPS post office in order to keep the tax agency up-to-date on details and avoid any future refund delays.
The average amount refunded was found to have increased this year, with people in Florida receiving an average of $100 more than 2008.