Medicare and Employer-Sponsored Group Health Plans - FAQ

Employee Benefits

Medicare and Employer-Sponsored Group Health Plans - FAQ

Medicare Basics

What is Medicare Part A?

Medicare Part A is hospitalization coverage. It covers eligible hospital expenses, skilled nursing care, home health care and hospice care.

What is Medicare Part B?

Medicare Part B is general medical coverage. It covers medical services, such as inpatient and outpatient medical services and doctors’ charges, office visits, therapy services and preventive care.

What is Medicare Part D?

Medicare Part D is prescription drug coverage.

What is Medicare Part C?

Medicare Part C is called “Medicare Advantage.” It is a plan intended to replace Parts A and B in a more controlled managed care setting (such as an HMO with a more restricted network of providers).

What is a Medigap Policy?

A Medigap, or Medicare Supplement policy, is a private insurance policy purchased to fill gaps in coverage not covered by Medicare Part A or B. For example, Medigap policies often cover hospital services beyond 90 days per benefit period, provide benefits for services not covered by Medicare, and pay some or all out-of-pocket expenses (e.g., Medicare Part A or B deductible and/or coinsurance).

When can individuals sign up for Medicare A or B?

In general, individuals can enroll in Medicare:

  • During the Medicare Open Enrollment Period that begins three months before their 65th birthday, includes their birthday month and ends three months after their 65th birthday month.
  • After age 65
    • Any time an individual is actively working and covered by their employer’s group health plan,1
      • Individuals working for employers with fewer than 20 employees should confirm with CMS that this enrollment opportunity is available.
    • During the Medicare Annual General Enrollment Period (AGEP) from January 1 through March 31 each year for coverage beginning July 1, or
    • During an eight-month special enrollment period that begins the earlier of (a) the date the individual retires or terminates employment or (b) the date their group health plan coverage ends.
    • When an individual is determined to be disabled by the Social Security Administration
      • Generally, entitlement begins after 24 months of Social Security Benefits, except if the individual is diagnosed with end-stage renal disease. When individuals first enroll in Medicare based on ESRD and are on dialysis, Medicare coverage usually begins with the fourth month of dialysis treatments but may begin earlier if the individual receives a kidney transplant.2

Is there a difference between being eligible for Medicare and being “entitled” to Medicare?

Yes. Under the Medicare rules, to be “entitled” to Medicare means a person is generally both eligible and enrolled. If the individual must take additional steps to enroll in Medicare before receiving benefits, then that individual is not entitled to Medicare.

1 CENTERS for MEDICARE & MEDICAID SERVICES – Enrolling in Medicare Part A & Part B
2 CENTERS for MEDICARE & MEDICAID SERVICES – Enrolling in Medicare Part A & Part B

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