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Medicare: All you need to know

What is Medicare?

Medicare is the federal health insurance program for people 65 or older, and for people of any age with certain disabilities.

When Medicare's an option, you'll have new insurance choices to consider. Our guide will help you figure out:

  • How Medicare works
  • What are the parts
  • Who's eligible
  • When to enroll
  • How to choose the best plan

For even more information, request our Medicare kit:

Medicare: The Next Chapter kit

If you're a member, you can always access our Medicare clinical guidelines and policies.

Policies and guidelines

How Medicare works

Medicare might seem complicated. But with a little knowledge, you can make the right coverage choices. We'll walk you through Medicare parts A, B, C, and D below.

You can also find all the Medicare coverage and service updates (also called determinations) made this year.

National coverage determination

Provider policies + guidelines

If you're a member, you can always access our Medicare clinical guidelines and reimbursement policies.

View provider policies + guidelines

Medicare Part A: Hospital coverage

Medicare Part A covers your inpatient hospital care. You don't need to pay a premium for Part A if you or your spouse worked at least 10 years.

Here are the types of hospital care that qualify for coverage.

Inpatient hospital care

This is care you get in hospitals, rehabilitation facilities, long-term care hospitals, and mental health care facilities. Coverage includes hospital services, semi-private rooms, meals, general nursing, and medications.

Part A in 2024

You pay

Days 1-60

Deductible of $1,632

Days 61-90

$408 copay per day

Days 91+

$816 copay per day

Skilled Nursing Facility (SNF) care

This covers care for a limited time in an SNF under certain conditions. Services include skilled nursing care, semi-private room, meals, physical and occupational therapy, medical social services, medications, ambulance transportation, and dietary counseling.

Part A in 2024

You pay

Days 1-20


Days 21–100

$204 copay per day

Days 101+

All costs for each day after day 100

Medicare Part B: Medical coverage

Medicare Part B covers your medical care. Services include doctor office visits, diagnostic tests, preventive care, medical supplies, and outpatient care. You pay a monthly premium for Part B to the federal government. Your Medicare Part B payment is usually deducted from your Social Security check. If you don't receive Social Security, you'll be billed quarterly.

Part B costs

This chart defines Part B out-of-pocket, including premium, deductible, and coinsurance amounts.

Part B in 2024

You pay

Monthly premium


Annual deductible


Medicare pays 80% of costs for eligible services and supplies

20% after deductible

* The Part B premium amount is higher for individuals with incomes over $103,000 or married couples with incomes over $206,000.

Medicare Part C: Medicare Advantage plans

When you choose a private Medicare Advantage plan, you agree to have the plan administer your Medicare Part A and Medicare Part B benefits. Medicare Advantage plans include hospital and medical coverage. They cover some of the costs that Medicare doesn't cover. Many also include Part D prescription drug coverage, which makes it easier for you by having all your hospital, medical, and prescription drug benefits in one plan.

Medicare Part D: Prescription drug plans

Medicare Part D prescription drug coverage is provided by private plans under contract with Medicare. You can join a Part D plan after your IEP, but if you delay enrollment you may have to pay a monthly late enrollment penalty for as long as you have Part D.

Part D options

Combined coverage plans

Combined coverage plans offer Part D drug plus hospital and medical coverage like Medicare Advantage plans.

Stand-alone coverage

Standalone coverage plans only provide Part D prescription drug coverage.

Part D drug plans have costs like deductibles and copays and most have premiums. These costs vary by plan, so it pays to shop around. Not all drugs are covered by all plans. Make sure your drugs are covered before you enroll in a plan.


Who’s eligible for Medicare?

Most people become eligible for Medicare at age 65. You don't have to be retired or collecting Social Security to be eligible. You may also be eligible before 65 if you're permanently disabled or have been diagnosed with end-stage renal disease (ESRD).

Medicare eligibility requirements:

  • You must be a U.S. citizen or a permanent legal resident for at least five consecutive years
  • You must also meet one or more of the following:
    • You're age 65 or older
    • You receive, or are eligible for, retirement benefits from Social Security or the Railroad Retirement Board
    • You’re any age and have a qualifying permanent disability
    • You need ongoing dialysis for end-stage renal disease (ESRD) or need a kidney transplant

Enrollment periods

Initial Enrollment Period (IEP)

If you're turning 65 soon, you can sign up during your IEP, which lasts for seven months. That seven-month time frame includes:

  • The three months before you turn 65
  • The month you turn 65
  • The three months after you turn 65
  • If you're enrolling for the first time due to disability, your IEP timing is based on your disability date.

During the IEP, you can sign up for any of the following:

  • Medicare Part A (Hospital coverage)
  • Medicare Part B (Medical coverage)
  • Medicare Part C (private Medicare Advantage plans)
  • Medicare Part D (private prescription drug plans)

If you want to be covered by Medicare during the month you turn 65, you need to sign up at least one month before your birthday month.

If you don't enroll in Medicare Part B or Part D during IEP, you may have to pay more to enroll later.

Annual Enrollment Periods

Sometimes the plan you choose isn't the right plan for you. These annual enrollment periods allow you to make changes to your plan.

Annual Open Enrollment Period: October 15 to December 7

If you make any plan changes, they'll go into effect on January 1. During annual open enrollment, you can choose to enroll, disenroll, or change your plan choices. Here are some examples:

  • Change from Original Medicare to a Medicare Advantage plan or vice-versa
  • Switch from a Cost plan with Part D to another Cost plan with Part D or an alternative private plan like Medicare Advantage
  • Switch from one Medicare Advantage plan to another Medicare Advantage plan or a Cost plan
  • Switch from one Medicare prescription drug plan to another Medicare prescription drug plan or a Medicare Advantage plan or Cost plan with Part D

Medicare Advantage Open Enrollment Period: January 1 to March 31

If you're enrolled in a Medicare Advantage plan, you have a one-time chance to:

  • Switch to a different Medicare Advantage plan
  • Drop your Medicare Advantage plan and return to Original Medicare (Part A and Part B)
  • Sign up for a standalone Medicare Part D prescription drug plan (if you return to Original Medicare)

Special Enrollment Periods (SEP)

An SEP lets you make coverage changes that you normally can only make during your Initial Enrollment Period (IEP) or open enrollment. There are many types of events that can trigger an SEP. Some examples are:

  • You move outside your plan's service area
  • You become eligible for Medicaid
  • You qualify for extra help with Medicare prescription drug costs
  • You lose prescription drug coverage from an employer or union, or your drug coverage is no longer as good as the standard Part D benefit

Other Enrollment Periods

Medicare Cost plans

You can join a Medicare Cost plan whenever these private plans are accepting new members.

If you're newly eligible for Medicare and enrolled in Medicare Part B, you can enroll in a Cost plan anytime during your seven-month IEP.

Medicare Supplement (Medigap) plans

The best time to enroll in a Medigap plan is during the six-month Medigap Open Enrollment Period, which begins the month you are both age 65 and enrolled in Part B. If you apply for coverage outside of your Open Enrollment Period, you may have to provide your health history and be medically underwritten. You could also be denied coverage or charged a higher rate.

How to Enroll in Medicare

If you're close to 65, but NOT getting Social Security or Railroad Retirement Board (RRB) benefits, you'll need to sign up for Medicare Part A and Part B.

Apply online at: ssa.gov/benefits/medicare

Or call Social Security at 1-800-772-1213 (TTY: 1-800-325-0778) from 7 a.m. – 7 p.m., Monday – Friday.

If you have received benefits for at least four months from Social Security or the Railroad Retirement Board by the time you turn 65:

You'll automatically be enrolled in Part A and Part B. Medicare will send you a card before you turn 65 with information on how to drop Part B, if you want to.

How to choose the best Medicare plan for you

Medicare doesn't cover all your health care costs. Many people choose to enroll in a private Medicare plan to cover costs Medicare alone doesn't cover.

Step 1: Learn about Medicare plan types

There are several types of private plans. It's important to understand them before you choose your coverage.

Medicare Advantage Plans

Medicare Advantage plans are private Part C plans that administer your Part A and Part B benefits on behalf of Medicare. They typically combine hospital, medical, and Part D drug coverage. Some offer extra benefits like dental, vision, hearing, and more. Medicare Advantage plans may charge a premium on top of your Part B premium. The premium may change annually, but it's not tied to your age.

You're eligible if you:
  • Are enrolled in Medicare Part A and Part B
  • Are a permanent resident in the plan's service area

Medicare Cost plans

Medicare Cost plans cover some costs that Original Medicare doesn't cover and may provide extra benefits like, dental, vision, and more. Some also offer optional Part D drug coverage.

Most Medicare Cost plans charge a premium on top of your Part B premium. The premium may change annually, but it's not tied to your age.

You're eligible if you:
  • Are enrolled in Medicare Part A and Part B or Part B only
  • Are a permanent resident in the plan's service area

Medicare Supplement (Medigap) Plans

Medicare Supplement plans (or Medigap plans) cover some costs that Original Medicare doesn't cover. Most plans have $0 copays. These plans don't include Part D drug coverage. Medicare Supplement plans charge a premium on top of your Part B premium. The premium is often tied to your age.

You're eligible if you:
  • Are enrolled in Medicare Part A and Part B
  • Are a permanent resident in the plan's service area at the time of enrollment

Step 2: Think about your needs

Review the questions below. Your answers will help guide you to the Medicare plans that may work best for you.

Is it more important for you to:

Pay a higher monthly premium and have lower out-of-pocket costs

Medicare plan options:

  • Medicare Cost plan
  • Medicare Supplement plan
  • Medicare Supplement plan + Part D prescription drug plan

Pay a lower monthly premium with higher out-of-pocket costs

Medicare plan options:

  • Medicare Advantage plan
  • Medicare Cost plan

Last updated: December 2023