Even with Medicare coverage, health-care costs are a major expense in retirement that can derail any financial plan if they're not factored in.

These costs are also hard to estimate because they depend on a person's health and longevity. Who wants to calculate when they are going to die?

Fortunately, or unfortunately depending on your retirement savings and fear of mortality, HealthView Services has crunched the numbers for a fit 65-year-old couple retiring this year and come up with an estimate of projected health-care expenses. The company, which helps financial advisors forecast health-care costs for their clients, used data from more than 50 million actual health cases to formulate its estimates. And the figure it came up with is more than most people have saved for retirement.

The average lifetime retirement health-care premium costs for the hypothetical couple is $266,589, which included Medicare parts B and D coverage as well as supplemental insurance, according to HealthView's latest report. (The estimate assumes a life expectancy of 87 years for men, and 89 for women.)

The costs are 6.5 percent more than HealthView's estimate last year and over $40,000 more than the retiree health-care cost estimate of $220,000 produced by Fidelity, which is widely used by financial advisors as a benchmark for such expenses.

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What's more daunting is a quarter of a million dollars only pays for basic coverage for this hypothetical, healthy 65-year-old couple. If you include dental, vision, co-pays and other out-of-pocket costs, the average cost estimate rises to $394,954. And for a healthy couple of 55-year-olds who plan to retire a decade from the now, retiree health-care costs beyond basic coverage are projected to be a whopping $463,849.

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