IRS: File your tax return or no stimulus check

The tax returns will be used to determine eligibility for the rebate payments, said IRS acting commissioner Linda Stiff.

Stiff said the IRS anticipates that some 10 million to 20 million additional returns will be filed by some low-income workers, retirees on Social Security, disabled veterans and retired railroad workers that were not previously required to file.

"Even if you did not otherwise earn enough to file a return, you will need to file a tax return. You must to do so to receive a payment," Stiff told a conference call.

The tax returns must show income of at least $3,000 in order to qualify for a $300 stimulus payment for an individual or $600 for a couple, plus $300 for each dependent child.

Social Security, Veterans Administration or other federal benefit payments can be applied toward this income level.

Most taxpayers will receive payments of $600 for an individual and $1,200 for a couple. IRS officials confirmed that the payments would not be subject to federal income taxes for the 2008 tax year.

Stiff said the IRS would engage in a "blitz" to notify Social Security recipients of the need to file a return, including mailings, public service announcements and working through social service organizations.

The U.S. Treasury's tax collection arm also is encouraging more tax filers to select a direct deposit option to have their tax refunds automatically deposited into their bank accounts.

If they do, their stimulus payments also will be deposited electronically, and Stiff said the money would be in their accounts more than a week faster than a paper check would sent out in the mail.