Medicare: Eligibility, Age, Qualifications, And Requirements

Fact Checked
Contributing expert: Kelly Blackwell, Certified Senior Advisor®
Updated: January 15, 2022

Understand who is eligible for Medicare, how much it costs, and how to enroll.



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Kelly Blackwell
Certified Senior Advisor (CSA)®
Kelly Blackwell
Certified Senior Advisor (CSA)®

Kelly Blackwell is a Certified Senior Advisor (CSA)®. She has been a healthcare professional for over 30 years, with experience working as a bedside nurse and as a Clinical Manager. She has a passion for educating, assisting and advising seniors throughout the healthcare process.

Medicare is health insurance for people who are 65 or older and for younger people with disabilities, ALS (Lou Gehrig’s Disease), or end-stage renal disease (ESRD). The federal government regulates and administers Medicare through the Centers for Medicare and Medicaid Services (CMS).

Read on for an explanation about who is eligible for Medicare, who qualifies for premium-free Part A and help with Medicare costs, and how to enroll in Medicare, Medigap, Medicare Advantage, and Prescription Drug coverage plans.

What Are the Basic Qualifications for Medicare Eligibility?

The basic qualifications that make you eligible for Medicare are:

  • You are a U.S. citizen or a legal resident who has lived in the U.S. for at least five years, and:
    • You are 65 years of age, or
    • You have a disability based on Social Security’s definition of total disability, or
    • You have ALS (Lou Gehrig’s Disease), or
    • You have ESRD (permanent kidney failure requiring dialysis or transplant)

Can You Qualify for Medicare if You Are Under 65?

You can qualify for Medicare if you are under the age of 65 and one of these situations applies to you. In any case, you are eligible for premium-free Part A:

  • You have a disability as defined by Social Security. Your Medicare coverage starts after receiving disability benefits from Social Security or the RRB for 24 months. If you are disabled but don’t receive disability benefits under SSA or RRB because you are a government employee, your Medicare coverage starts after 29 months.
  • You have Amyotrophic Lateral Sclerosis (ALS) (Lou Gehrig’s Disease). Coverage starts when you are entitled to Social Security or RRB disability benefits. There is no waiting period.

You have kidney disease requiring dialysis or transplant. You must have completed a Medicare application. You or your spouse must have worked long enough under Social Security, the RRB, or as a government employee to be eligible for retirement benefits. Your Medicare coverage start dates work differently if you have end-stage kidney disease. Click here for more details.

How Do You Enroll in Medicare?

If you’ve received retirement benefits for at least four months before you turn 65, you are automatically enrolled in Medicare A and B. You can opt out of Part B if you are still covered under an employer-sponsored group health plan. If you wait to enroll in Part B and don’t have group coverage, you may have to pay a penalty.

The Social Security Administration (SSA) usually handles Medicare enrollment, but if you worked for the railroad, you enroll in Medicare through the Railroad Retirement Board (RRB).

If you have not received retirement benefits, you will need to self-enroll. Sign up for Medicare through Social Security or call 1-800-772-1213. If you were a railroad worker, visit the RRB website or call 1-877-772-5772.

If you are within three months of your 65th birthday and you are not yet ready to take Social Security, you can apply online for Medicare only through Social Security.

Medicare enrollment opportunities: 
Initial Enrollment Period (IEP): This is the best time to enroll in Medicare if you aren’t automatically enrolled. This seven-month period starts three months before the month you turn 65, includes your birthday month, and extends three months after your birthday month. If you enroll during the first three months of your IEP, your Medicare coverage will start on the first of the month you turn 65. If you enroll in months four through seven of your IEP, your Part A coverage will be retroactive to the first day of your birthday month. Your Part B coverage will be delayed two to three months.
General Open Enrollment Period: If you miss your IEP, you can enroll in Medicare during this time which occurs annually between January 1 and March 31. Coverage starts on July 1.
Special Enrollment Period (SEP): You may qualify for a SEP if your circumstances change. For example, you change where you live, or you lose your group coverage. Depending on your circumstance, you will have a period of time to enroll in Medicare without penalties. Coverage typically starts the first of the month following enrollment.

How Do You Enroll in Medicare Supplement, Medicare Advantage, and Medicare Prescription Plans?

Medicare Supplement Insurance (Medigap), Medicare Advantage, and Medicare Prescription Drug plans are administered by private insurance companies approved and regulated by Medicare. The company you choose or a licensed agent can help with your enrollment. You can find these plans on Medicare.gov.

  • Medicare Supplement Insurance (Medigap): You must have Original Medicare to purchase a Medigap plan. You can enroll during your IEP. If you only have Part A but have not enrolled in Part B yet, you can enroll in a Medigap plan with guaranteed issue rights within six months after you are 65 and have Part B. You cannot have both a Medicare Advantage plan and a Medigap plan. Suppose you drop your Medicare Advantage plan and return to Original Medicare within the first year of having a Medicare Advantage plan. In that case, you may be able to purchase a Medigap plan. If you wait, you may not be able to purchase a Medigap plan or may have to pay more based on your health condition.
  • Medicare Advantage: You must have Part A and Part B to enroll in a Medicare Advantage Plan. You can join a plan during your IEP or during the annual open enrollment period from October 15 through December 7. If you already have a Medicare Advantage Plan, you can make a change during the Medicare Advantage Open Enrollment period from January 1 through March 31. See 2022 Medicare Advantage plans here.
  • Prescription Drug Plan (Part D): You must have Part A and Part B to enroll in a Medicare drug plan, either through your Medicare Advantage plan or a stand-alone drug plan. You can enroll during your IEP or during the annual open enrollment period from October 15 through December 7. Suppose you are in a Medicare Advantage plan with drug coverage. In that case, you can switch to another plan or switch back to Original Medicare plus a stand-alone drug plan one time during the General Open Enrollment period from January 1 to March 31. See 2022 Drug plans here.

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