WASHINGTON (AP) _ Ooops. The government's official handbook for explaining Medicare to beneficiaries contains an error pertaining to the new prescription drug benefit that kicks in Jan. 1.

The 35 million handbooks are being shipped in waves. Some beneficiaries may have them as soon as this weekend.

Gary Karr, a spokesman for the Centers for Medicare and Medicaid Services, said the agency erred when listing the prescription drug plans available with no monthly premium for low-income beneficiaries.

The booklets listed all of the plans available for those with limited assets and income as having no monthly premium. But only about 40 percent of the plans actually qualify for no premium.

Karr said the agency will work with groups to help people get the correct information. It will also instruct companies not approved to offer zero premiums on what they can tell potential enrollees.

``It must tell them our plan can't give you a free premium, but there are other plans which can,'' Karr said.

The extra subsidy is available for those whose income does not exceed $14,355 for an individual or $19,245 for a couple. Karr said the mistake was because of inadequate proofreading.