The guarantee, which may lead to higher private insurance premiums, is one of several new consumer protections for elderly people buying health insurance to supplement Medicare.

Two said they had had private insurance to supplement Medicare.

The rising costs of prescription drugs are driving up the premiums of insurance plans that supplement traditional Medicare and include drug coverage.

In addition, the agreement for the first time provides coverage of prescription drugs, supplementing Medicare, for retirees 65 and over.

And they pushed through a pilot project to allow the elderly to make tax-free contributions into their own accounts to supplement Medicare.

Gina Vazquez, 66, said, "I have secondary coverage" to supplement Medicare.

Such employer-sponsored benefits typically supplement Medicare, which is much less comprehensive than the health insurance that many workers now receive from their employers.

A private insurer offering coverage to supplement Medicare would have to use one of the 10 models.

Many Medicare recipients receive coverage through former employers, group health plans or private insurance policies that supplement Medicare.

In addition, many beneficiaries pay $200 to $400 a year in premiums for private insurance to supplement Medicare.