Eligibility for Medicare coverage begins at age 65. Those who retire before this age and lose health insurance coverage provided by their employer will pay considerably more for health insurance until they become eligible for Medicare. The cost of monthly premiums increases steadily with age, peaking at age 64. In addition to the cost of premiums, out-of-pocket expenses constitute a significant though less predictable cost. Depending on the plan coverage and healthcare needs of the individual, total median annual healthcare costs including both premiums and out-of-pocket expenses for a 64-year-old female can range from $8,000 to $20,500.