The Internal Revenue Service said that about 5.2 million retirees and disabled veterans who qualify for economic stimulus payments have not filed to claim the payments.

So far, about 74 percent of the people in this group have filed tax returns this year in order to claim the payments, even though they normally do not file. The IRS is planning to start a summer campaign to reach this group and encourage them to file a return to get the payment process going.

A special stimulus category includes recipients of certain benefits from Social Security and Veterans Affairs who are not normally required to file a tax return. However, these individuals must file before Oct. 15 to receive their economic stimulus payments.

"Some retirees and others who normally do not file a tax return may be eligible and not know it," said IRS Commissioner Doug Shulman (pictured) in a statement.

Later this summer, the agency will send them a special letter that explains stimulus payment eligibility and how to claim it. The letter will include a sample tax form and an actual tax form that they can complete and mail to the IRS. This will be the second special mailing to reach those individuals.

The IRS also is working with members of Congress, state and local officials, and national partners such as AARP, the National Council on Aging, United Way of America, the National Disability Institute and others to continue its outreach efforts to the retiree and veterans' communities through the summer. It will conduct face-to-face free tax preparation sessions with the help of local community partners at locations such as senior housing, Veterans Affairs hospitals and assisted-living facilities.