IRS has issued about $64B in stimulus checks

The agency estimates there are about 20 million retirees and veterans who don't normally file returns but must do so by Oct. 15 this year to get their rebate checks. Of those, about 5.2 million have yet to file.

The IRS has sent letters to potential recipients and worked with state and local officials and groups such as AARP to let retirees and veterans know that they must file returns to get a check and that those checks will have no impact on other federal benefits they currently receive.

Shulman said they would mail another packet of information and launch a public relations campaign aimed at areas of the country where non-filing has been greatest.