Thinking of calling the IRS about your rebate check? So are thousands of others.

The Internal Revenue Service said the agency has been flooded recently with phone calls about the upcoming rebates guaranteed under President Bush's economic stimulus plan.

By the end of April, the agency expects to have fielded some 1.8 million calls related to rebates. ABC News says the group is now receiving an extra 50,000 calls a day.

As a result, employees are being pulled from other duties to man the phones.

So far, more than 1,500 IRS employees have been reassigned to work the phones. The U.S. Government Accountability Office said this could cost the IRS as much as $681 million in uncollected taxes.

The IRS warned lawmakers that the current tax season could mean a delay in sending out the rebate checks.

Social security numbers are being used to determine the order the checks are mailed in. Those whose social security numbers end in between 00 and 20 will get their check first.

Rebates sent by direct deposit are supposed to start on May 2 and paper checks should follow on May 16.

Sources: CBN News, The Associated Press, ABC