The Centers for Medicare and Medicaid Services has told Humana Inc. to stop mailing subscribers a letter suggesting that health care reform legislation could cause them to lose Medicare Advantage benefits and services.

The Humana letter warns that enrollees could lose Medicare Advantage plan access, “ultimately urging them ‘to contact congressional representatives to protest actions referenced in the letter,’” Teresa DeCaro, acting director of the CMS’ Medicare Drug and Health Plan Contract Administration Group, writes in a letter sent Friday to Gail Miller, a vice president at Humana, Louisville, Ky.

CMS is concerned that, “among other things, this information is misleading and confusing to beneficiaries, represents information to beneficiaries as official communications about the Medicare Advantage program, and is potentially contrary to federal regulations and guidance for the Medicare Advantage and Part D programs under Medicare and other federal laws,” DeCaro writes.

“As we continue our research into this issue, we are instructing you to end immediately all such mailings to beneficiaries and to remove any related materials directed to Medicare enrollees from your website,” DeCaro writes.

Humana is cooperating with CMS on resolving concerns about the enrollee mailing, says Tom Noland, a Humana spokesman.

DeCaro sent the letter to Humana in response to a request from Senate Finance Committee Chairman Max Baucus, D-Mont. who has accused Humana of misrepresenting the Medicare Advantage provisions in his America’s Healthy Future Act proposal.

The Senate Finance Committee is set to begin marking up an AHFA bill Tuesday.

The AHFA proposal could cut the total amount of funding set to go to the Medicare Advantage program by about $123 billion over the next 10 years, according to a Congressional Budget Office estimate released Wednesday.

Other proposals circulating in Congress could cut the Medicare Advantage budget allocation by about $175 billion over 10 years.

Advocates of the cuts want to use the money to help pay for health coverage for Americans who are now uninsured.

Baucus said today that he has asked CMS to “condemn” insurance industry “scare tactics,” Baucus said the health reform legislation he introduced “will include significant improvements to the Medicare program that will benefit seniors.”

It is “wholly unacceptable for insurance companies to mislead seniors regarding any subject – particularly on a subject as important to them, and to the nation, as health care reform,” Baucus said.

The “false claims” in the Humana letter to beneficiaries include the allegation that seniors could lose Medicare Advantage program benefits, Baucus said.

Baucus said his legislation does not include cuts to Medicare benefits and would, instead, “improve the value of Medicare Advantage by reforming payments so that they appropriately reimburse insurers for their costs and promote plans that offer high quality, efficient health care for seniors.”

He also noted that that the independent Medicare Payment Advisory Commission has found that even after controlling for the cost of delivering benefits, of marketing, and of profits, Medicare Advantage plans get 14% more, on average, than the traditional Medicare program.