According to a Nationwide Financial survey, nine in 10 retirees with at least $250,000 in household assets are not concerned about paying for their future health care costs beyond what Medicare covers.

Ninety-three percent of retired Americans say they are at least somewhat confident they can pay for their future health care costs, yet 46% of Baby Boomers nearing retirement with the same amount of assets say they are “terrified” of health care costs.

“The good news is we’re not seeing the panic that many Boomers nearing retirement are having, but we hope this isn’t over-confidence that could lead to a lack of preparedness down the road,” said John Carter, president of Nationwide Financial Distributors Inc., a subsidiary of Nationwide Financial. “For many of the retirees we surveyed, most of their health care costs have yet to come.”

Carter said despite retirees’ confidence in paying for health care costs, Boomers should not think it will be as easy when they retire. “Many Boomers can expect a very different retirement than that of their parents,” he said. “In addition to higher health care costs and longer life expectancies, Boomers likely won’t have pensions or employer-paid health care, and realistically they’ll need to be prepared to pay for their own health care costs in retirement.”

According to the survey, 40% of those in retirement say their biggest expense is paying monthly housing bills; 21% say the cost of health care; and 16% say providing for their family. Those nearing retirement say they expect health care to be their biggest expense (45%), followed by monthly housing bills (35%) and providing for their family (9%).

Retirees, on average, estimate they spend $4,083 each year on health care for things like premiums, copayments and deductibles, while 21% estimate they spend less than $1,499 each year and 22% say they are unsure of how much they spend.

Retiree health care costs have increased an average of 6% a year since 2002, which translates to a 65-year-old couple retiring today needing $240,000 to cover medical expenses during their retirement years (which could take up to 35% of the couple’s annual Social Security benefit). This number does not include long-term care costs.

“Too many people underestimate the amount of money needed to cover their health care costs in retirement because they do not think they will ever need long-term care,” said Kevin McGarry, director of the Nationwide Institute.

The U.S. Department of Health and Human Services, however, estimates that people over the age of 65 have a 70% chance of needing long-term care.

The survey also found that about two in five retirees (39%) say they wish they understood Medicare coverage better. But only about one in six retirees say they plan to meet with their financial adviser to discuss health care costs beyond those covered by Medicare. Of those who have met with an adviser, 70% say it was helpful to very helpful in estimating future health care costs.

Nationwide’s survey of 1,250 Americans with at least $250,000 in household assets—including 625 retirees—was conducted by Harris Interactive.