Tired of worrying about whether you'll have enough money to live on in retirement? Okay, maybe you'd rather worry about how you'll pay your medical costs during those, um, golden years.

Those costs, including insurance premiums, are a bigger problem than you -- and apparently most policymakers -- may have realized.

In a new study, Paul Fronstin and Dallas Salisbury of the nonprofit Employee Benefit Research Institute in the District have analyzed the cost of those premiums, along with the inevitable co-payments and deductibles, and come up with some figures on how much individual retirees will likely need to cover them.

The numbers are startling.

A 65-year-old living where Medigap premiums are moderate, such as Arizona or the District of Columbia, who retired this year with no employer-sponsored coverage, would need $47,000 in savings to pay just the premiums for Medicare Part B coverage and the most comprehensive of the 10 standard Medigap policies -- Plan J -- between now and age 80, the study figures. It would take $66,000 to remain covered to age 85. That doesn't include nursing-home care.

In Florida, where Medigap insurance is particularly expensive, such a retiree would need the equivalent of $82,000 to make it to 80 and $115,000 to 85.

These figures assume that insurance costs (inflation combined with the effect of growing older, which makes coverage more expensive) rise at only 7 percent a year. If these costs rise at, say, 14 percent -- which may seem high but is hardly impossible -- a retiree this year would need $335,000 in savings to pay the premiums.

Living longer and having claims, which would trigger co-pays and deductibles, would boost the requirement even more.

The study's results are "eye-popping" and "a real wake-up call," Salisbury said last week.

He said researchers had taken comfort in recent federal laws meant to guarantee individuals the right to buy medical insurance and hadn't really examined what that would cost.

"When you consider that the premium for a 55-year-old today is close to $15,000 for individual coverage, that's a lot of money," Salisbury said.

The findings underline those of earlier studies of income needs done in Massachusetts, Kansas and Oregon, which showed that "even if you look at income from all sources, if you then factor in what people need for medical care, you find that 60 percent of elderly widows" and about 40 percent of single men "come up short," he added.

The new study looked at three scenarios: retirement at 55, retirement at 65 with employer-sponsored insurance, and retirement at 65 with no employer insurance. It ran numbers for those circumstances for retirement in 2003 and for the two 65-year-old groups for retirement in 2013.

It found that retirees who have any help from their former employer do better. The share of companies that provide such coverage has been slipping -- from 20 percent in 1997 to 11 percent today -- and is expected to continue to decline. And those that continue to provide coverage are requiring retirees to pay a greater share -- in many cases, all -- of the premiums. But it remains true, the study found, that retirees who have access to an employee coverage -- even on an "access only" basis, meaning they have to pay the entire premium -- still get a meaningful benefit.

But Fronstin and Salisbury caution that as more employers switch to "access only" plans, healthier retirees will drop out and sicker ones hang in, creating what is called "adverse selection" and driving up the price.

Workers who retire this year and have employer-sponsored medical insurance would need to have saved $37,000 to pay for coverage through age 80 if they have to pick up half the premium of the employer's plan. They would need to have saved $62,000 if they have to pay all of the premium.

For coverage through age 85, savings of $52,000 would be needed by those who have to pay half the premium and $109,000 by those who pay the entire premium. (These figures assume 7 percent annual increases in premiums and no co-pays or deductibles -- in other words, no claims.)

But those numbers are for this year. The future looks even worse.

A retiree reaching 65 and retiring 10 years from now would need $158,000 to pay premiums through age 80 and $223,000 to reach 85. If life expectancies increase, a reasonable possibility, such retirees may live to 90 and need $297,000 -- or to 95 and need $479,000.

And all these numbers are likely to be low for many retirees. Those who are sick and draw on their coverage frequently would need much more. And of course, the calculations are for individuals -- a couple should double everything.

The report also notes that retirees face a much less helpful tax environment. For example, employers get a full deduction for medical premiums, but retirees do not. They get a deduction only if medical costs exceed 7.5 percent of adjusted gross income, and then the deduction is only for the amount over the 7.5 percent.

The report cites a number of policy options that government could consider, ranging from tax breaks to a broad expansion of Medicare to a retiree-health-care mandate imposed on employers. And Salisbury observed in an interview that one benefit of President Bush's proposed tax-free savings plans would be to enable workers to pre-fund their retiree health care costs.

It's not clear, of course, which of these might best solve the problem, or whether there is any solution. As our ability to treat disease gets better and better, our ability to pay for it gets worse and worse.