Medicare Basics

Medicare is a program administered by the federal government that provides insurance options for individuals age 65 or older, or any age for those who qualify because of certain disabilities or medical conditions. Medicare comes in four parts: Part A, Part B, Part C and Part D. Original Medicare, provided by the federal government, includes Part A and Part B.

Part A: Hospital coverage

When you're first eligible for Medicare, you have a 7-month initial enrollment period to sign up for Part A and/or Part B, but some people are enrolled in Part A and Part B automatically.

Most people get premium-free Part A. You usually don't pay a premium if you or your spouse paid Medicare taxes while working. You can get premium-free Part A at 65 if:

  • You already get retirement benefits from Social Security or the Railroad Retirement Board.
  • You're eligible to get Social Security or Railroad benefits but haven't filed for them yet.
  • You or your spouse had Medicare-covered government employment.

If you're younger than 65, you can get premium-free Part A if:

  • You got Social Security or Railroad Retirement Board disability benefits for 24 months.
  • You have End-Stage Renal Disease (ESRD) and meet certain requirements.

If you get Medicare automatically, you'll get your red, white and blue Medicare card in the mail three months before your 65th birthday or your 25th month of disability.

You may need to sign up for Part A & Part B if:

  • You aren't getting Social Security or Railroad Retirement Board benefits (for example, because you're still working).
  • You qualify for Medicare because you have End-Stage Renal Disease (ESRD).
  • You live in Puerto Rico and want to sign up for Part B (you automatically get Part A). You must already have Part A to apply for Part B.

Part A covers inpatient expenses. These costs usually include:

  • Inpatient hospital care
  • Inpatient stays in most skilled-nursing facilities
  • Hospice and home health services

Part A does not cover all inpatient expenses. You are responsible for paying some costs before your benefits apply, such as your deductible, and certain costs after the deductible is met.

The federal government administers Part A. To learn more about Medicare Part A, visit

Part B: Medical coverage

After you are Medicare eligible, you can choose to enroll in Medicare Part B.

Part B provides coverage for medically necessary services and preventive services.This coverage typically includes:

  • Doctor and clinical lab services
  • Outpatient and preventive care
  • Screenings, surgical fees and supplies
  • Physical and occupational therapy
  • Clinical research
  • Ambulance services
  • Durable medical equipment (DME)
  • Mental health
  • Getting a second opinion before surgery
  • Limited outpatient prescription drugs

If you enroll in Part B, you will be responsible for some costs:

  • Your monthly premium, which is usually deducted from your Social Security payment
  • Specific out-of-pocket expenses, such as your deductible and any cost share (copays and coinsurance) amounts

The federal government administers Part B. To learn more about Medicare Part B, including costs and how to enroll, visit

Part C (Medicare Advantage): Additional benefits, assured access to providers

Medicare Part C, or Medicare Advantage, is an alternative that covers the benefits of Medicare Parts A and B, and may offer additional benefits.

Private insurance companies such as Asuris administer Medicare Advantage plans. When you choose a Medicare Advantage plan, you get the same coverage as Medicare Parts A and B, plus benefits that Original Medicare does not cover. These additional benefits vary among individual carriers, but may include features such as dental care, gym memberships and vision care. You can also select a Medicare Advantage plan that includes Rx.

Medicare Advantage plans give you guaranteed access to a wide range of physicians and other health care professionals.

If you purchase a Medicare Advantage plan, you may pay a monthly premium and a percentage of some costs. You will also be required to continue paying for your Medicare Part B premium.

Medicare Part D: Prescription drug coverage

Medicare Part D is administered by private insurance companies, such as Asuris, that offer Prescription Drug Plans to cover prescription drugs.

If you enroll in Original Medicare, you can purchase a stand-alone Prescription Drug Plan (PDP) to help cover your prescription medication. Or, you can choose to enroll in a Medicare Advantage plan (instead of Original Medicare) that includes prescription drug coverage.

If you purchase a PDP, you may be responsible for paying a monthly plan premium. You may also need to pay either a copay or coinsurance amount for your prescriptions.

Some plans may also require you to meet a deductible before your benefits apply.

Learn more about the different coverage gap stages and out-of-pocket cost information in your Summary of Benefits document.

Medigap: Filling in the gaps

A Medigap (Medicare Supplement) plan is administered through private insurance companies, such as Asuris. It provides coverage for some health care costs that Original Medicare alone doesn't cover, such as copays, deductibles or coinsurance.

You must be enrolled in Medicare Part A and Part B before you can enroll in a Medigap plan.

Medigap plans do not include prescription drug coverage. However, you can purchase stand-alone Medicare Part D coverage.

Medigap plans are not tied to networks; if you travel and want to see providers in different cities, Medigap may be a good choice for you.

If you purchase a Medigap plan, you pay a monthly premium. Many Medigap plans have lower out-of-pocket costs than other Medicare options.

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Last updated 04/10/2024