PHOENIX -- The Internal Revenue Service has 3,237 refund checks for Arizona taxpayers worth more than $3.8 million.

The IRS said the checks were returned by the post office because of mailing-address errors.

Across the nation, refunds worth $123.5 million are waiting for taxpayers to claim them.

IRS Commissioner Doug Shulman said the agency is eager to get the money to taxpayers owed a refund.

Undeliverable refund checks average $1,178 per Arizonan this year, up from $1,023 last year.

If a check is returned to the IRS as undeliverable, taxpayers can update their addresses with the "Where's My Refund?" tool at IRS.gov or call 1-800-829-1954.