The Internal Revenue Service is trying to contact about 700 Hawaii taxpayers who have not received tax refund checks totaling more than $680,000, after the checks were returned to the IRS by the Postal Service because of mailing address errors.

Taxpayers who believe their refund check was returned because of an address error can go to the "Where's My Refund?" tool on IRS.gov and update their address. Once the IRS receives an updated address from a taxpayer, it can mail out the refund check.

The Web site tool enables taxpayers to check the status of their refunds. A taxpayer must submit his or her social security number, filing status and amount of refund shown on their 2008 return. Taxpayers also can access a telephone version of "Where's My Refund?" by calling 1-800-829-1954.