What Is Medicare? Who Qualifies and How the Parts Fit

Medicare is the federal health insurance program most people in the United States join around age 65. It can be confusing because it comes in parts, the parts can be combined in different ways, and some pieces are run by private companies under Medicare's rules.

This guide gives you the big picture: who qualifies, how enrollment starts, what each part does, and the two main ways to put coverage together.

This is general information, not insurance, legal, tax or medical advice. EZ Health Benefits is an independent guide and is not connected with Medicare, the Centers for Medicare & Medicaid Services (CMS) or any insurance plan. For help with your own situation, contact your State Health Insurance Assistance Program (SHIP), call 1-800-MEDICARE (1-800-633-4227), or talk with a licensed professional.

Who qualifies for Medicare

Medicare.gov describes Medicare as health insurance for people 65 or older who meet citizenship or residency requirements. You may also qualify earlier if you have a disability, End-Stage Renal Disease (ESRD), or ALS (also called Lou Gehrig's disease).

The residency rule changed recently, and the Medicare & You 2027 handbook flags it as a change. To get Part A and Part B benefits or join a Medicare health or drug plan, Medicare.gov says you must be one of the following:

• A U.S. citizen or U.S. national
• A lawful permanent resident (green card holder)
• A Cuban-Haitian entrant
• Someone lawfully living in the U.S. as a Compact of Free Association (COFA) migrant

For people under 65, the Medicare & You 2027 handbook says you get Part A and Part B automatically after 24 months of Social Security disability benefits (or certain Railroad Retirement Board disability benefits). People with ALS get Medicare automatically the month their Social Security disability benefits begin. People with ESRD have to sign up.

Getting Medicare: automatic or sign up yourself

Whether you have to take action depends mostly on Social Security. According to the Medicare & You 2027 handbook, if you already get Social Security or Railroad Retirement Board benefits, you are enrolled in Part A and Part B automatically, starting the first day of the month you turn 65. Your red, white and blue Medicare card arrives in the mail about 3 months before your 65th birthday.

If you are close to 65 but not yet collecting Social Security, you generally need to sign up through Social Security. In Puerto Rico, people get Part A automatically but must sign up for Part B.

Timing matters. The handbook warns that if you don't sign up for Part B when you are first eligible, you may face a delay in coverage and a late enrollment penalty added to your premium for as long as you have Part B. People who are still working with job-based coverage often have different options. Our guide "Medicare With Job, VA or TRICARE Coverage: Who Pays First" walks through those cases. The sign-up windows themselves are covered in the Enrolling & Choosing section of this site.

The parts of Medicare at a glance

Medicare's parts are named with letters. Here is what each one does, based on Medicare.gov's overview:

• Part A (Hospital Insurance) helps cover inpatient hospital care, skilled nursing facility care, hospice care and home health care.
• Part B (Medical Insurance) helps cover services from doctors and other providers, outpatient care, home health care, durable medical equipment like walkers and wheelchairs, and many preventive services such as screenings and vaccines.
• Part C is another name for Medicare Advantage, a way to get your Part A and Part B benefits through a Medicare-approved private plan.
• Part D (Drug Coverage) helps pay for prescription drugs and is offered through private plans that follow Medicare's rules.

Most people do not pay a monthly premium for Part A. Medicare.gov says that for 2026, premium-free Part A applies to most people because they or a spouse paid Medicare taxes long enough while working (generally at least 10 years). Part B has a monthly premium. Medicare.gov lists the standard 2026 Part B premium as $202.90, and higher-income people pay more. For full cost details, see the Costs & Help Paying section of this site.

Two main ways to get your coverage

Once you have Part A and Part B, Medicare.gov describes two main paths.

Original Medicare is Part A plus Part B. You can use any doctor or hospital in the U.S. that takes Medicare. You can add a separate Part D drug plan, and you can buy supplemental coverage such as a Medicare Supplement Insurance (Medigap) policy to help with your share of costs. Without supplemental coverage, Original Medicare has no yearly limit on what you pay out of pocket.

Medicare Advantage (Part C) is a private plan, approved by Medicare, that bundles Part A, Part B and usually Part D. Plans often use provider networks and may require prior authorization for some services. They also have a yearly out-of-pocket limit and often offer extras such as some vision, hearing or dental benefits.

Neither choice is right for everyone, and this site does not recommend specific plans. Medicare.gov also points out that Medicare doesn't offer couples or family plans, so you don't have to make the same choice as your spouse.

What Medicare usually doesn't cover

New enrollees are often surprised by the gaps. The Medicare & You 2027 handbook lists items Original Medicare generally doesn't cover, including:

• Non-medical long-term care, such as help with bathing and dressing in a nursing home or at home
• Most dental care, including routine cleanings, fillings and dentures
• Eye exams for prescription glasses
• Hearing aids and exams for fitting them
• Routine physical exams
• Cosmetic surgery

Medicaid (for people who qualify), private long-term care insurance, or a Medicare Advantage plan's extra benefits may fill some of these gaps. Otherwise, you pay these costs yourself.

Medicare and Medicaid are different programs

The names are similar, but the programs are not. Medicare.gov explains that Medicare is federal health insurance based mainly on age or disability. Medicaid is a joint federal and state program for certain people with low income, and the eligibility rules vary by state. You can have both. People with both are called "dually eligible." Medicare pays first, and Medicaid can help with Medicare premiums and costs, as well as some services Medicare doesn't cover, like long-term nursing home care.

Protect your Medicare Number

Medicare cards carry a Medicare Number that scammers want. The Medicare & You 2027 handbook advises giving that number only to your doctors and other providers, your insurer or plan (and its licensed agents or brokers), or state assistance programs that work with Medicare. The handbook says Medicare will call you only in limited situations, such as returning a call you asked for. If someone contacts you out of the blue asking for your Medicare Number, hang up and call 1-800-MEDICARE yourself.

Where to get personal help

Good help is free. SHIPs are state programs that receive federal funding to give local health insurance counseling to people with Medicare. The Medicare & You 2027 handbook notes that SHIPs aren't connected to any insurance company or health plan. The SHIP National Technical Assistance Center's website lists the SHIP for each state. You can also call 1-800-MEDICARE, or call your state insurance department with questions about insurance sold in your state.

Key takeaways

• Medicare is federal health insurance for people 65 and older who meet citizenship or residency rules, plus some younger people with disabilities, ESRD or ALS.
• If you already get Social Security benefits, you are generally enrolled in Part A and Part B automatically at 65. Otherwise, you usually need to sign up.
• Part A covers hospital-type care, Part B covers doctor and outpatient care, Part D covers drugs, and Part C (Medicare Advantage) is the private-plan way to get A and B.
• Original Medicare and Medicare Advantage are the two main paths. Each has trade-offs, and you choose for yourself, not as a couple.
• Medicare generally doesn't cover non-medical long-term care, most dental care, routine eye exams or hearing aids.
• For free, unbiased one-on-one help, contact your local SHIP or 1-800-MEDICARE.

Sources

• Medicare.gov, Get started with Medicare
• Medicare.gov, Parts of Medicare
• Medicare.gov, How does Medicare work?
• Centers for Medicare & Medicaid Services, Medicare & You 2027 (official U.S. government Medicare handbook)
• Medicare.gov, Costs (2026 amounts)
• Medicare.gov, Medicaid
• SHIP National Technical Assistance Center, Get Medicare Help from Your Local SHIP Program