Taxpayers who file electronically can use the service within 72 hours of submitting their returns. Paper filers can use "Where's My Refund?" three to four weeks after their returns are mailed.

"Taxpayers have discovered that 'Where's My Refund?' is a fast, easy way to check on their refunds," said IRS Commissioner Mark Everson.

The "Where's My Refund?" service is accessible from the IRS.gov homepage. Instructions guide individual taxpayers through a process that asks for three pieces of information from their returns: Social Security Number, filing status and refund amount.

Once the information is submitted, "Where's My Refund?" notifies the taxpayer whether the return was received and is being processed, and, if processed, the expected mailing date or direct-deposit date for the refund. The service will also notify a taxpayer if a refund has been returned to the IRS as undeliverable.

In cases where a refund is delayed because of a math error or other issue, "Where's My Refund?" will advise the taxpayer on steps he or she can take to resolve the problem.

Taxpayers can ensure a successful experience by entering the requested information exactly as it appears on their tax returns filed with the IRS.

The "Where's My Refund?" service debuted nearly two years ago. It handled more than 18 million electronic inquiries in 2003.