No one enjoys paying taxes, but you can take some satisfaction knowing that some of your hard-earned money goes to two government programs that provide health protection for a fraction of what you would pay for private insurance. These government-sponsored plans help ensure that almost everyone who is older than 65 — and those who are disabled, regardless of age — gets the basic health coverage they need.

Medicare is the nation's largest health insurance program, covering about 40 million Americans. It gives coverage regardless of income.

However, Medicare doesn't provide complete protection. It does not cover prescription medications, long-term care or dental care. That's why people who enroll in Medicare buy supplemental insurance as well, when they can afford it.

Under Medicare, you get two plans: Medicare Part A and Medicare Part B. Each part covers different things (and has different requirements), so you need to know the differences.

Here's what you get from Medicare Part A:

• You are covered for up to 90 days of inpatient hospital care during each "benefit period." A benefit period is measured from the time you start receiving care to the time you leave the hospital. There's no limit to the number of benefit periods.
• You may also be eligible for home health care, hospice care or short-term treatment in a skilled nursing facility following a hospital stay.

And here's what you get from Medicare Part B:

• Doctors' fees
• Outpatient hospital services, including emergency room visits
• Diagnostic tests
• Some preventive care, such as mammograms, colon cancer screening, flu and pneumonia vaccinations and diabetes self-management
• Special medical equipment, such as wheelchairs

Medicare Part B typically covers only a part of these costs. You may be responsible for making a co-payment, usually 20% of the amount approved by Medicare.

You're eligible for Medicare as long as you (or your spouse) is 65, have worked for at least 10 years and have paid payroll taxes. You may also be covered if you have a permanent disability, no matter what your age.

You will receive an enrollment notice in the mail about three months before your 65th birthday. Or you can contact your local Social Security office to obtain the form. (If you're already receiving Social Security or railroad retirement benefits, you're automatically enrolled.) Once you fill out the form and send it in, you're covered for Part A. That's all you have to do.

Medicare Part B, however, is optional. You must pay $45.50 per month and a $100 deductible each calendar year. You can opt out of Part B by checking a box on the enrollment form. But if you change your mind and want to enroll later, you will pay an additional 10% for every year you wait to enroll.

About 95% of the Medicare population gets Part B. Even if you have other insurance, you'll still want to get it. It may cover things that private Medigap insurance doesn't cover.

Turn in the form, make sure your doctor is a Medicare provider, and you're done. But now, things get more complicated. As with any insurance plan, Medicare doesn't cover everything. You're probably going to need some additional coverage.

Most people who get Medicare also purchase supplemental insurance, called Medigap. Medigap polices are sold by private companies but are regulated by the states. There are 10 different Medigap polices, designated by the letters A to J. The A policy provides basic coverage; the J policy gives the most protection.

With so many policies to choose from, the coverage varies widely. Benefits might include:

• Payment of Medicare deductibles
• Partial payment of prescription drugs
• Payment for at-home care
• Additional coverage for extended hospital or nursing home stays

Choosing a Medigap policy can be time-consuming, but it's worth looking at the options closely to make sure you're getting the coverage you need.

You won't need Medigap if you've signed up for a Medicare managed care plan, also known as Medicare Part C. This plan helps cover the cost of medications, as well as most of the services provided by Medigap.

The majority of people covered by Medicare are 65 and older, but the program also provides coverage for younger folks with serious disabilities. In order to qualify, you must prove that you're totally and permanently disabled and unable to work.

The provisions for getting Medicare if you have a disability include:

• You've received Social Security disability benefits for at least two years.
• You're a U.S. citizen or a resident alien who's been in the country five years or more.
• You've received disability benefits from the Railroad Retirement Board.
• You have fulfilled a five-month Medicare waiting period.
• You (or your spouse) have permanent kidney failure and receive dialysis or have had a kidney transplant.

Unlike Medicare, which is administered by the federal government, Medicaid is run by the states. This insurance program is based entirely on financial need. Most people receiving Medicaid are low-income children and families, but Medicaid is available to low-income elderly people. It covers medications and nursing home care.

Although Medicare and Medicaid are separate programs, some people qualify for both. being covered by both programs does away with almost all out-of-pocket health care expenses, because Medicaid pays for monthly Medicare premiums and co-payments to doctors, plus it covers services that Medicare does not. People who exhaust their financial resources after an extended illness, regardless of their age, can turn to Medicaid for help.

Medicaid covers a wide range of services, including inpatient and outpatient hospital care, medical supplies, transportation to services and long-term care.

For more-detailed information about Medicare, you can access medicare.gov or the AARP Web site at www.aarp.org. The Kaiser Family Foundation Web site at www.kff.org also provides more thorough information about both Medicare and Medicaid.