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Medicare Eligibility

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As you approach retirement age, you're probably wondering if you're eligible for Medicare. Considering that nearly 64 million Americans are enrolled in Medicare and the majority are 65 years old or older, odds are that you'll be eligible to enroll too.1 To qualify, you do need to meet some eligibility requirements. Even if you don't meet all of the requirements, it likely just means that you'll need to pay a little extra to get the health care coverage you want.

In this guide, we'll cover the ins and outs of Medicare eligibility for Part A, Part B, Part C, Part D, and Medicare Supplement plans. Plus, we'll take a look at when you can actually enroll in a Medicare program.

Table of Contents

Medicare Part A Eligibility

The good news is that nearly every American adult age 65 and older qualifies for Medicare. Along with meeting the age requirement, you also need to be a U.S. citizen or a permanent resident of the United States.2

Premium-Free Part A Eligibility

Most older adults are eligible for premium-free Medicare Part A based on their earnings or their spouse's earnings. You can get premium-free part A at age 65 if:

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

You or your spouse must have paid Medicare taxes for at least 40 quarters while working to receive premium-free Part A.3 That's the equivalent of 10 full years of work, but the quarters do not need to be consecutive.

Clipboard with document that says "Medicare"; medical professional speaking to person in wheelchair.

Premium Part A Eligibility

You can buy Medicare Part A if you're not eligible for premium-free Part A. To buy Part A, you must have Medicare Part B and you must pay monthly premiums for Medicare Part A and Medicare Part B.

Eligibility Example: John is a 65-year-old U.S. citizen. He's not married and has paid taxes for only 32 quarters. John doesn't qualify for premium-free Part A, so he will need to enroll in Medicare Part B if he wants to buy a Medicare Part A plan.

Medicare Part B Eligibility

Medicare Part B is a voluntary Medicare program. In other words, you'll need to pay a monthly premium for Medicare Part B. There isn't a “premium-free” Medicare Part B option. Eligibility for Part B depends on which type of Medicare Part A you qualify for.

Adults who are eligible for premium-free Medicare Part A are eligible to enroll in Part B.

Adults age 65 or older who pay a premium for Medicare Part A need to meet the following criteria to enroll in Part B:

  • Be a U.S. resident and
  • Be either a U.S. citizen or
  • Be an alien who has been lawfully admitted for permanent residence and has been residing in the United States for five continuous years prior to the month of filing an application for Medicare4

FYI: Want to learn more about Medicare's medical insurance? Check out our comprehensive guide to Medicare Part B.

Medicare Eligibility If You Are Under 65

Under age 65? You could still qualify for Medicare benefits. The government makes age exceptions for individuals with certain medical conditions or disabilities. Here are the scenarios in which you could be eligible for Medicare:


If you receive Social Security (SS) or Railroad Retirement Board (RRB) benefits due to a disability, you're eligible for Part A. There is a 24-month waiting period. Federal, state, and local government employees who aren't eligible for SS or RRB benefits but who are deemed entitled to disability benefits are eligible for Part A. There is a 29-month waiting period.

ALS Diagnosis

If you have amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease), you are eligible for Part A during the first month that you're eligible for SS or RRB disability cash benefits. There is no waiting period.

End-Stage Renal Disease (ESRD)

You may qualify for premium-free Part A if you receive regular dialysis treatments or have had a kidney transplant. You also need to meet at least one of the following conditions:

  • You worked the required amount of time under SS, the RRB, or as a government employee.
  • You are receiving or are eligible for SS or RRB benefits.
  • You are the spouse or dependent child of someone who meets one of the previous two conditions.

Medicare Part C Eligibility

Original Medicare isn't the only way to get your Medicare Part A and Part B benefits. Instead, you can enroll in a Medicare Advantage plan, also called Medicare Part C or an MA plan. MA plans are offered by private companies that provide your Original Medicare benefits plus extras. These extras might include fitness programs, prescription drug coverage (Part D), vision services, hearing services, dental services, or meal delivery after a hospitalization.

Did You Know? Around 28 million people are enrolled in a Medicare Part C plan. That's 45 percent of all Medicare beneficiaries.5 Read our Medicare Advantage guide to see if a Part C plan makes sense for you.

Since Medicare Part C is just a different way of receiving Medicare Part A and Part B benefits, the same eligibility criteria apply — with one addition: You must live in the service area for the Medicare Advantage plan that you want to join.

Medicare Part D Eligibility

Medicare Part D plans add prescription drug coverage to Original Medicare. Some Medicare Advantage plans include Part D automatically. To qualify for a Part D plan, you must have Medicare Part A and/or Medicare Part B. That means, you must also be a U.S. citizen or be lawfully present in the U.S.6

Medicare Supplement (Medigap) Eligibility

Medigap plans help to fill the “gaps” in your Original Medicare coverage. These privately offered plans can help you with copayments, coinsurance, deductibles, and more. To qualify for a Medigap policy, you must have Medicare Part A and Part B through Original Medicare. You cannot sign up for a Medigap plan if you have a Medicare Advantage plan.

Quick Tip: Interested in a Medicare Supplement plan? Check out our list of the best Medigap plans.

Medicare Enrollment Periods

You can't sign up for Medicare whenever you feel like it, especially if you want to avoid late fees. Instead, you'll need to sign up for Medicare during a designated enrollment period. The easiest thing to do is to sign up during your Initial Enrollment Period, which takes place right around your 65th birthday. Doing this ensures that you won't owe any ongoing late-enrollment penalties.

The chart below explains the different types of Medicare enrollment periods, including a brief description and when they take place.7

Types of Medicare enrollment periods Description When is It? Additional notes
Initial Enrollment Period (IEP) This is the first opportunity for eligible adults to enroll in Original Medicare or a Medicare Advantage Plan. This is the 7-month period surrounding your 65th birthday. It starts three months before your birth month, includes your birth month, and ends three months after your birth month. For example, if your birthday is June 28, your IEP will begin on March 1 and end on September 30.
Medicare Annual Enrollment Period (AEP) Anyone with Medicare can join, drop, or switch to another plan during this period. This includes Medicare Advantage and Medicare Part D plans. October 15 to December 7
Medicare's Special Enrollment Period (SEP) People with certain special circumstances may be able to make changes to their Medicare enrollment during this period. Qualifying special circumstances include:

  • Job retirement after age 65
  • A move
  • You become eligible for Medicaid
  • Insurer terminates your Medicare plan
  • You lose other medical or drug coverage
When a qualifying event occurs Length of enrollment period varies based on your circumstance
Medicare Advantage Open Enrollment Period (OEP) Current Medicare Advantage enrollees can switch to a different Medicare Advantage plan or switch to Original Medicare and obtain Part D coverage. January 1 to March 31
Medigap Open Enrollment Period This is the time when you can sign up for a Medigap policy. This is a 6-month period that starts the first month you have Medicare Part B insurance and you’re 65 or older. Insurers can more easily deny you a Medigap policy if you apply outside of the Medigap OEP.
General Enrollment Period (GEP) You can sign up for Medicare during this time, but you might owe a monthly late-enrollment penalty unless you qualify for a Special Enrollment Period. January 1 to March 31 If you have Medicare Part A and sign up for Medicare Part B during the GEP, you can then sign up for a Medicare Advantage plan from April 1 to June 30.

You can also sign up for a Medicare drug plan during this time even if you do not have Medicare Part A.

Did You Know? During your Medigap Open Enrollment Period, insurers can't use medical underwriting. That means they can't refuse to sell you any of their Medigap policies and they can't charge you more for one of their policies.

Written By

Sarah Goldy-Brown

Writer & Researcher

Sarah covers a range of senior lifestyle topics, from reviews of walk-in tubs and hearing aids to overviews of Medicare and Medicaid. Her close relationship with her grandparents gave her a firsthand look at the evolving life needs of older adults, and… Learn More About Sarah Goldy-Brown