Medicare is health insurance run by the federal government for people 65 and older, some younger people with disabilities, and people with end-stage renal disease

Medicare has four parts, each covering different things. Part A covers hospital stays, skilled nursing care, and hospice. Part B covers doctor visits, outpatient care, and medical equipment. Part D covers prescription drugs. Part C, also called Medicare Advantage, is an alternative way to get Parts A and B through a private insurance company, often bundled with Part D and sometimes dental or vision.

You become may be able to access for Medicare the month you turn 65, regardless of whether you are still working. If you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease or ALS, you can get Medicare before 65. Most people pay a monthly premium for Part B and Part D, and some pay a premium for Part A if they do not have enough work credits. You also pay out-of-pocket costs — deductibles, copayments, and coinsurance — when you use care.

Key Takeaways

  • Medicare Part A covers hospital care, Part B covers doctor visits and outpatient services, and Part D covers prescription drugs; Part C bundles A and B through a private insurer.
  • You enroll during your Initial Enrollment Period, which starts three months before the month you turn 65 and lasts for seven months; missing this window can mean permanent late-enrollment penalties.
  • Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years; Part B and Part D have monthly premiums that vary based on your income.
  • Original Medicare (Parts A and B) has no network restrictions, but you pay deductibles and coinsurance; Medicare Advantage (Part C) often has lower out-of-pocket costs but limits you to in-network providers.
  • You can change your coverage during the Annual Enrollment Period (October 15 to December 7 each year) or during special enrollment periods if you have a may have access to life event.

The Four Parts of Medicare and What Each Covers

Part A covers inpatient hospital care, including room, meals, and nursing care. It also covers up to 100 days in a skilled nursing facility after a hospital stay of at least three days, home health services ordered by a doctor, and hospice care. Part A does not cover long-term custodial care in a nursing home or assisted living facility.

Part B covers doctor office visits, preventive care like annual wellness visits and cancer screenings, outpatient hospital services, physical therapy, mental health counseling, and durable medical equipment like wheelchairs and oxygen. Part B requires a monthly premium, and you pay a yearly deductible before coverage begins. After you meet the deductible, you typically pay 20 percent coinsurance for most services.

Part D is prescription drug coverage. Each plan covers a different list of drugs, so the medications you take matter when you choose a plan. You pay a monthly premium, and your costs depend on which tier your drug falls into — generic drugs usually cost less than brand-name drugs. There is a coverage gap called the "donut hole" where you pay more out of pocket once you and your plan have spent a certain amount, though this gap has been shrinking in recent years.

Part C, or Medicare Advantage, is sold by private insurance companies and must include everything Part A and B cover, but often adds dental, vision, or hearing coverage. The trade-off is that you must use doctors and hospitals in the plan's network, except in emergencies. Many Medicare Advantage plans have $0 premiums, but you still pay Part B premiums to Medicare, and you may pay higher copayments or coinsurance than in Original Medicare.

When and How to Enroll in Medicare

Your Initial Enrollment Period is seven months long: it starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your period runs from March through September. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

If you miss your Initial Enrollment Period, you can still enroll, but you will pay a permanent late-enrollment penalty on your Part B and Part D premiums for as long as you have Medicare. The penalty is 10 percent of the Part B premium for each full 12-month period you were not enrolled, and a similar amount for Part D. This penalty does not go away, so enrolling on time matters.

If you are still working and have health insurance through your job, you may be able to delay Part B enrollment without penalty if your employer has 20 or more employees. You will need to enroll within eight months of leaving your job or losing that coverage. This is called the Special Enrollment Period.

After your Initial Enrollment Period, you can change your coverage during the Annual Enrollment Period, which runs from October 15 to December 7 each year. Changes take effect January 1. You can also switch plans during a Special Enrollment Period if you move, lose other coverage, or have certain other may have access to events.

How Much Medicare Costs

Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years (40 quarters of work). If you do not have 40 quarters, you can buy Part A, but the monthly premium is higher than Part B. If you have between 30 and 39 quarters, you pay a reduced premium.

Part B has a monthly premium that changes each year. In 2024, the standard premium was $164.90 per month, but it varies based on your income. If your income is above a certain threshold, you pay an Income-Related Monthly Adjustment Amount (IRMAA) on top of the standard premium. The income thresholds are based on your Modified Adjusted Gross Income from two years prior.

Part D premiums vary widely depending on which plan you choose. Some plans cost $5 to $10 per month, while others cost $50 or more. The amount also depends on your income — higher earners pay an IRMAA surcharge. You can compare plans and their costs on Medicare.gov.

Beyond premiums, you pay out-of-pocket costs when you use care. In Original Medicare (Parts A and B), you pay a deductible before coverage starts, then you pay coinsurance or copayments. In Medicare Advantage, your costs depend on the plan — some have $0 deductibles but higher copayments, while others have higher deductibles but lower copayments.

Original Medicare Versus Medicare Advantage

Original Medicare is the traditional program run directly by the federal government. You can see any doctor or hospital that accepts Medicare, anywhere in the country. There are no networks, so you have more freedom in choosing providers. However, you pay a yearly deductible for Part B ($240 in 2024), and then you pay 20 percent coinsurance for most services. There is no annual out-of-pocket maximum in Original Medicare, so your costs can be very high if you have serious health problems.

Medicare Advantage is an alternative offered by private insurance companies. These plans must cover everything Original Medicare covers, but they often add extras like dental, vision, or hearing. Many have $0 monthly premiums (though you still pay Part B premiums to Medicare). However, you must use doctors and hospitals in the plan's network, and you may need referrals to see specialists. Most Medicare Advantage plans have an annual out-of-pocket maximum, which means your costs are capped.

If you choose Original Medicare, you can buy a Medigap policy from a private insurance company to help pay your out-of-pocket costs. Medigap policies are standardized, so Plan G from one company covers the same things as Plan G from another. Medigap is not the same as Medicare Advantage — you can have Original Medicare plus Medigap, but you cannot have both Medigap and Medicare Advantage at the same time.

Preventive Care and Wellness Benefits

Medicare covers many preventive services at no cost to you, even if you have not met your Part B deductible. These include an annual wellness visit with your doctor, cancer screenings (mammograms, colonoscopies, Pap tests), cardiovascular screenings, diabetes screenings, bone density tests, and vaccinations like the flu shot and pneumonia vaccine. You pay nothing for these services if your doctor accepts Medicare assignment.

The annual wellness visit is different from a regular doctor visit. It is a chance to review your health history, update your medications, and talk about preventive care and health goals. You should schedule this visit every year, even if you feel fine. It helps your doctor catch problems early and keeps your preventive care on track.

Frequently Asked Questions

Do I have to enroll in Medicare when I turn 65?

Yes, you should enroll during your Initial Enrollment Period, which starts three months before you turn 65. If you delay enrollment without a valid reason, you will pay a permanent late-enrollment penalty on your Part B and Part D premiums. The only exception is if you are still working and have health insurance through your employer with 20 or more employees.

What is the difference between Medicare and Medicaid?

Medicare is federal health insurance for people 65 and older and some younger people with disabilities, based on work history. Medicaid is a joint federal and state program for people with low income, regardless of age. They are separate programs with different rules, may be able to access, and coverage.

Can I use my Medicare outside the United States?

Original Medicare generally does not cover care outside the U.S., except in limited situations like emergency care in Canada or Mexico near the border. Some Medicare Advantage plans offer limited international coverage. If you travel abroad, you may want to buy supplemental travel insurance.

What happens to my Medicare if I move to a different state?

Your Medicare coverage continues, but your Medicare Advantage plan or Medigap policy may not be available in your new state. You will have a Special Enrollment Period to change plans after you move. Original Medicare works the same in every state.

How do I know if my doctor accepts Medicare?

You can search for doctors on Medicare.gov or call your doctor's office directly and ask if they accept Medicare. Some doctors accept Medicare but do not accept assignment, which means they can charge you more than Medicare allows. Ask whether your doctor accepts assignment before scheduling an appointment.