Medicare: Eligibility, Age, Qualifications, and Requirements

Fact Checked

Medicare is health insurance for people who are age 65 or older and for younger people with disabilities, amyotrophic lateral sclerosis (ALS or 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, Medicare Supplement Insurance plans (Medigap), Medicare Part C (Advantage), and Prescription Drug coverage plans.

What Are the Basic Qualifications for Medicare Eligibility?

Who is Eligible for Medicare Health Insurance?

Be a United States citizen or resident who has lived in the US for at least 5 years and at least one of the following:

  • Age 65+
  • Disabled (based on SSI definitions)
  • Have ALS
  • Have ESRD

The basic qualifications that make you eligible for health insurance through Medicare are:

  • You are a United States 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
    • Have a disability based on the Social Security’s definition of total disability, or
    • Have ALS, or
    • Have ESRD (permanent kidney failure requiring dialysis or transplant)
    • You worked and paid Medicare taxes for at least 10 years

Can You Qualify for Medicare If You Are Under 65?

You can qualify for Medicare benefits if you are younger than 65 and one of these situations applies to you. In any case, you are eligible for premium-free Part A hospital insurance:

  • You have a disability as defined by Social Security. You will become eligible for Medicare coverage after receiving your monthly social security or the U.S. Railroad Retirement Board for 24 months. If you are disabled but don’t receive disability benefits under United States Social Security or qualify for RRB benefits because you are a government employee, the 24 months is extended to 29 months.
  • You have ALS. Coverage starts when you are entitled to receive 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 age 65, you are enrolled automatically in Medicare A and B. As you walk through the process, you can tap into helpful tools including an eligibility premium calculator and find out your potential part premium.

If you’ve received retirement benefits for at least four months before you turn age 65, you are enrolled automatically 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.

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

If you are within three months of becoming age 65 and you are not yet ready to be receiving Social Security, you can apply online for Medicare only through Social Security and use their tools to find out information like eligibility premium, along with details about Medicare part hospital, Medicare part medical, Medicare supplement,. And what you can do so you do not pay late enrollment fees.

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 are age 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.
  • Open Enrollment Period (OEP): 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 following initial enrollment. 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.

What’s important to know is that you could face a late enrollment penalty if you neglect to enroll in coverage during these periods.

How Do You Enroll in Medicare Supplement, Medicare Advantage (Part C), and Medicare Prescription Plans?

Medigap, Medicare Part C, 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. During your time working, you pay medicare taxes through your employer. Medicare taxes allow this health insurance coverage to be available.

As for finding plans, you can view options on, where there is also a premium calculator and you can learn more about part coverage. An explanation of each:

  • 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 the annual OEP from October 15 through December 7. If you already have a Medicare Advantage Plan, you can make a change during the OEP 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 OEP 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 Medicare part or switch back to Original Medicare plus a stand-alone drug plan one time during the OEP from January 1 to March 31. See 2022 drug plans here.


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Certified Senior Advisor (CSA)Ⓡ

As a health care professional since 1987, Kelly Blackwell has walked alongside and cared for seniors as they journey through the season of their fourth quarter of life. Blackwell holds a Bachelor of Science in nursing from the University of Northern Colorado, a Master of Science in health care administration from Grand Canyon University, an interprofessional graduate certificate in palliative care from the University of Colorado Anschutz Medical Campus and holds a Certified Senior Advisor® credential from the Society of Certified Senior Advisors.

Blackwell contributes to the University of Colorado-Anschutz blog and has been published in “The Human Touch” distributed by the University of Colorado Center for Bioethics and Humanities. She cowrote “Dying Is” for Pathways Hospice.

A registered nurse, Blackwell understands health insurance choices influence quality of life and are driven by values, goals, and beliefs. She’s passionate about engaging with, educating, and empowering seniors as they navigate the health care system. She’s equipped to lend an experienced, compassionate voice to beneficiaries seeking information about Medicare Advantage Plans.

As a CSAⓇ, Blackwell has access to valuable resources for Medicare beneficiaries. Her work as a bedside nurse and clinical manager has given her the opportunity to see how Medicare rules, regulations, and benefits work when patients need them. With a passion to learn and to make a difference in the lives of seniors, Blackwell supports seniors through Medicare and fourth-quarter life decisions.

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