Louis deBottari, a 78-year-old retired aerospace worker with good drug insurance, recently opened an envelope from The Boeing Co., hoping to be reassured.

The notice, sent to about 100,000 Boeing retirees and their dependents, discussed the new Medicare drug insurance program that begins in January and what it means for retirees already covered by the company's health plan.

But a bit farther down came a warning, if deBottari were nonetheless tempted to give the new Medicare program, called Part D, a try: "Your Boeing prescription drug coverage is part of your Boeing retiree medical plan. If you cancel your Boeing prescription drug coverage, your Boeing medical coverage also will be canceled."

Many other retirees fortunate enough to already have drug coverage are receiving similar warnings from their former employers as the new Medicare drug benefit approaches.

This was not necessarily what Congress intended when it passed the Medicare law two years ago, extending drug insurance to more than 40 million older and disabled Americans.

The aim then was to provide benefits similar to those already enjoyed by a more fortunate minority of retirees - about 10 million, currently - who have drug coverage from former employers.

In practice, though, that fortunate minority is worrying about the future of their own benefits. And the message many are receiving from their former employers is a surprisingly stern one: Stay put - or else.

The attitude might be understandable. Many employers generally offer drug benefits within a comprehensive package that also covers doctors' services and hospital care.

They typically do not charge a separate premium for drug coverage and do not administer it as a separate benefit. And so they say they have no convenient way to split up the benefits package they now offer.

There is another factor. Like other employers that continue offering drug insurance as good or better than Medicare's, Boeing will receive a federal subsidy for the drug purchases of each retiree it retains.

Many of those companies have shown little interest in continuing to provide other, increasingly expensive health coverage to a retiree if they lose the drug subsidy.

And so deBottari is staying put and trying to ignore that big employers like General Motors are trimming their retiree health benefits and that Wall Street analysts are predicting many other employers will eventually scale back or even end their own drug programs, relegating retirees to the less generous Medicare plans they are now being advised to avoid.

By Nov. 15, all employers who offer drug coverage to retirees and employees 65 and older are required to send word to those beneficiaries, indicating how the company's drug plan compares with Part D. Employers also must inform retirees of any changes in their existing health benefits.

In a survey early this year of 458 large employers that had retiree health plans, 82 percent said they planned to continue drug coverage for retirees under those plans, according to the benefits consulting firm Watson Wyatt.

During the current advisory period, many large employers that offer retiree drug coverage - including GM, Caterpillar, Verizon Communications, SBC Communications and the Southern Co. - are, like Boeing, telling their people that the company's plan is as good or better than the Medicare drug program.

And "more so than not, plan sponsors are saying if you join Medicare Part D, you will be out of our plan," said Edward Kaplan, a senior health care consultant at the Segal Co., a benefits consulting firm.

Staying in a company's plan allows retirees to fend off an often bewildering array of choices touted by insurers and other private sponsors of Part D plans, which are overseen by Medicare but provided by private industry.

older Americans could face up to 45 Medicare plan choices, with premiums that average $32 a month but whose coverage and co-payments vary widely.

People who want to sign up for a Medicare drug plan can do so penalty-free from Nov. 15 to May 15. There could be increasingly stiff late-fee penalties for those who delay.

But the penalties will not apply to retirees who have solid employer-sponsored coverage but who shift later to a Medicare plan - if, say, their current employer-sponsored plans are curtailed or ended.

The number of companies providing retiree health benefits has been shrinking for decades, as rising costs for drugs and other health needs have cut sharply into profits. And benefit consultants say that many employers, after seeing how things work out with the Medicare subsidies in 2006, will be weighing possible changes in their retiree benefits for 2007 and beyond.

This year, even before Part D became an issue, Visteon, an auto parts maker, said it would no longer provide health benefits to salaried workers who retire after June 2007.

Airlines like Northwest and United have been cutting retiree benefits in bankruptcy proceedings. Sears is eliminating retiree health benefits for younger current employees and new hires.

"The government will actually pay employers to continue to provide something," said Helen Darling, president of the National Business Group on Health, an organization of large employers. "If this works, it may be a model for some other things in the future."

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