What Age Does Medicare Start and When Can You Enroll?

Most people can enroll in Medicare around the age of 65.

Emily Guy Birken
Emily Guy Birken
  • Plutus Award winner

  • 12+ years writing about insurance and personal finance

Emily is a widely recognized expert on personal finance and has authored several personal finance books. She’s a frequent guest on national and regional media.

Featured in

media logomedia logomedia logo
Katie Powers
Edited byKatie Powers
Photo of an Insurify author
Katie PowersAuto and Life Insurance Editor
  • Licensed auto and home insurance agent

  • 3+ years experience in insurance and personal finance editing

Katie uses her knowledge and expertise as a licensed property and casualty agent in Massachusetts to help readers understand the complexities of insurance shopping.

Featured in

media logomedia logo

Updated March 15, 2023

Insurify partners with top insurance companies to provide a comprehensive comparison experience. However, the insurance experts writing our content operate independently of our partners. Check out reviews from over 3,000 satisfied customers, how we make money, our data methodology, and our editorial standards.

Most Americans can enroll in Medicare when they turn 65. However, some situations allow you to qualify for Medicare at a different age or time. Though enrolling in Medicare is generally a simple process, you should be aware of some things before you enroll. Understanding the rules surrounding Medicare eligibility and enrollment can help you feel more confident navigating this program.

When does Medicare coverage start for most people?

For most Medicare beneficiaries, Original Medicare (which includes Medicare Parts A and B) begins around the age of 65, during something known as the initial enrollment period.

This seven-month enrollment period begins three months before you turn 65, includes the month of your 65th birthday, and ends three months after you turn 65.[1] For example, if you turn 65 on Feb. 4, 2024, your initial enrollment period spans the full seven months from Nov. 1, 2023, to May 31, 2024.

Signing up for Medicare after the seven-month initial enrollment period could also result in a late enrollment penalty.[2] However, several situations allow Medicare beneficiaries to enroll either earlier or later than age 65 without facing a penalty.

See More: Do I Need Health Insurance Coverage?

When does Medicare coverage start for people with disabilities?

Americans with disabilities and other qualifying conditions can access Medicare benefits before age 65.[3] To receive these early benefits, you’ll have to meet one of the following requirements:

  1. You receive Social Security Disability Insurance (SSDI) benefits. You’re eligible for Medicare coverage after receiving 24 months of SSDI benefits and will be automatically enrolled as of the 25th month you receive SSDI benefits. If you receive SSDI benefits because you have Amyotrophic Lateral Sclerosis, or ALS, you’ll automatically be enrolled in Medicare coverage in the same month your SSDI benefits begin.

  2. You have been diagnosed with End-Stage Renal Disease (ESRD). You may qualify for Medicare if you have kidney failure and are either receiving dialysis or had a previous kidney transplant. You’ll qualify if you’re eligible to receive SSDI, railroad retirement benefits, and/or Medicare because you or a spouse has worked 10 years in a job that pays into Medicare.

Learn More: How To Compare Medicare Advantage and Get The Best Plan

When are the Medicare enrollment periods?

Enrollment in Medicare occurs during specific time periods. The enrollment period you choose can affect the amount you pay, options available to you, and when your coverage begins. 

Here’s what you need to know about each enrollment period.

Initial enrollment period

The initial enrollment period centers around when you turn 65. The seven-month period spans the three months prior to your birthday month, the month you turn 65, and the three months following your birthday month.

For most Medicare beneficiaries, this period is the best time to enroll in Medicare Parts A and B because there’s no fee or penalty for enrolling. If you enroll sometime in the three months prior to your 65th birthday month, your coverage will begin on the first day of the month you turn 65. If you enroll during your birthday month or in the three following months, your coverage will begin on the first day of the month following your enrollment.

General enrollment period

The general enrollment period lasts between Jan. 1 and March 31 every year. Your Medicare coverage will begin on the first of the month after you enroll during this period. If you miss your initial enrollment period window, you must enroll during the general enrollment period and face late enrollment penalties.

The Part A late enrollment penalty only applies to Medicare beneficiaries ineligible for premium-free Medicare Part A, but the Part B late enrollment penalty affects all Medicare beneficiaries who miss the initial enrollment period.[4]

Special enrollment period

Some circumstances allow you to enroll in Medicare Parts A and B after your initial enrollment period without a late enrollment fee.

Special enrollment periods most commonly occur because you had health insurance coverage through your or a spouse’s job during your initial enrollment period. You don’t have to sign up for Medicare during the initial enrollment period if you have employer-sponsored healthcare. You’re allowed to enroll in Medicare at any time during the eight-month period that begins after either your employment or health insurance coverage ends.

You may also qualify for a special enrollment period if you: 

  • Lost Medicaid coverage

  • Encountered a natural disaster during your initial enrollment period

  • Received misleading or inaccurate information from your health insurer or employer

  • Were incarcerated during your initial enrollment period

  • Volunteer and serve in a foreign country

  • Have TRICARE

What is your Medicare effective date?

The Medicare effective date is the first day you’re covered by Medicare. Coverage always begins on the first day of the month, but your specific effective date depends on when you enroll.

When You EnrollMedicare Effective Date
First three months of your initial enrollment periodFirst of the month you turn 65
Last four months of your initial enrollment periodFirst of the month after you enroll
General enrollment periodFirst of the month after you enroll
Special enrollment periodFirst of the month after you enroll

Check Out: How Long Does Health Insurance Last After You Quit a Job?

How to enroll in Medicare

The process for enrolling in Medicare varies depending on your circumstances. Some beneficiaries are automatically enrolled, while others need to manually enroll. Additionally, enrolling in Original Medicare (Parts A and B) differs from enrolling in a Medicare Advantage Plan or a Medicare Supplement Plan. 

Here’s what you need to know about the enrollment process.

Automatic enrollment

Automatic enrollment into Medicare Parts A and B will apply to you in the following circumstances:[5]

  1. You already receive Social Security retirement benefits. Coverage will automatically begin on the first day of the month you turn 65.

  2. You have been receiving Social Security disability benefits (SSDI) for 24 months. You’ll automatically receive Medicare Parts A and B benefits on the first day of the 25th month of receiving SSDI benefits.

  3. You have ALS. You’ll be automatically enrolled in Medicare Parts A and B in the same month that you begin receiving SSDI benefits.

Good to know

Generally, the Medicare premiums will be deducted from your Social Security benefits when you’re automatically enrolled. You’ll receive your Medicare card in the mail three months before your 65th birthday, or one month before your 25th month of SSDI benefits.

What to do if you’re not automatically enrolled

If you don’t receive Social Security disability benefits or retirement benefits prior to age 65, you won’t be automatically enrolled in Medicare. You need to sign up manually. However, Medicare sends a welcome package with all the information you need to enroll.[6] 

You can start your application online to sign up for Medicare through the Social Security Administration, or call a representative at 1 (800) 772-1213. The welcome package will explain in detail how to enroll if you file for your retirement benefits when you turn 65, or later.

When you can start a Medicare Advantage plan

A Medicare Advantage plan, sometimes referred to as Medicare Part C, allows you to get all the insurance included in Original Medicare through a private insurer.

If you’re new to Medicare Advantage plans, you can enroll during one of these enrollment periods:

  • Initial enrollment period: If you ask to join a plan before your Medicare coverage starts, your plan coverage will begin on the same day as your Medicare starts. If you ask to join a plan during this period but after your Medicare coverage has started, the plan coverage begins the first day of the month after the insurer receives your request.

  • Open enrollment: This period spans from  Oct. 15 to Dec. 7 every year. Coverage begins on Jan. 1 of the following year.

Important Information

If you’re already covered by a Medicare Advantage plan, you can switch to another plan or drop your plan and go back to Original Medicare during the Medicare Advantage open enrollment period from Jan. 1 to March 31 of each year. Alternatively, you can switch or drop your Medicare Advantage plan in the first three months after you get Medicare. Coverage begins on the first of the month following your request.[7]

Read More: What Is Medicare Advantage and Is It Right for You?

When to start a Medicare supplement plan

Medicare supplement, or Medigap, plans help you pay for some of the costs Medicare doesn’t cover, such as deductibles, copayments, and co-insurance. You can’t have a Medicare Advantage plan and a Medicare supplement plan at the same time.

To be eligible for a Medicare supplement plan, you must be enrolled in Medicare Parts A and B. Medigap plans have a six-month open enrollment period that starts on the first day of the month in which you are both over the age of 65 and enrolled in Medicare Part B.[8] During this window, you can purchase any Medigap policy offered by insurance companies that service your area. If you miss this window, insurers can decide whether they will insure you and how much to charge you.

What is the late enrollment penalty?

If you don’t enroll during your initial enrollment period, you may face a late enrollment penalty. This penalty adds 10% to the cost of your Part A monthly premiums for every year that you were eligible to enroll and didn’t.

If you’re not eligible for premium-free Part A coverage, this penalty will last for twice the number of years that you were eligible but didn’t enroll. If you’re eligible for premium-free Part A, there’s no penalty. The late enrollment penalty for Part B is also a 10% increase on your monthly premiums, but it’s a lifetime penalty.

See Also: Medigap vs. Medicare Advantage: Which Plan Is Best for You?

What are the parts of Medicare?

Medicare is divided into four parts, often labeled Parts A through D:

  • Part A: This covers inpatient hospital and skilled nursing facility care, home healthcare, and hospice care. Most Medicare beneficiaries don’t owe a premium for Part A.

  • Part B: This includes services from doctors and other healthcare providers, outpatient care, home healthcare, durable medical equipment, and some preventive care. All Medicare beneficiaries must pay a monthly premium for Part B.

  • Part C (Medicare Advantage): These are insurance plans from Medicare-approved private insurance companies.

  • Part D: This provides drug coverage through private insurers. Parts A and B don’t cover self-administered prescriptions, so Medicare beneficiaries with Original Medicare may want this plan to help them afford prescription drugs.[9]

How much does Medicare cost?

The cost of Medicare varies depending on each person’s circumstances. All the costs included below for premiums and deductibles come from the Centers for Medicare and Medicaid Services.[10] Several factors determine the amount you’ll pay annually for Medicare, including:

  • Premiums: The standard monthly Part B premium in 2023 is about $165. Medicare beneficiaries with an income below $97,000 or a married income below $194,000 will pay that premium amount. Beneficiaries with higher incomes will pay more. Part C and D premiums vary by insurer. You’ll pay the plan’s basic premium if your income is below $97,000 as a single person or $194,000 as a married couple. Beneficiaries with higher income will pay the plan premium plus an additional amount.

  • Deductibles: You’ll need to pay $1,600 per benefit period before your Part A coverage kicks in for covered hospital stays. Then, Medicare pays for all your care for the first 60 days in the hospital or the first 20 days in a skilled nursing facility. For Part B coverage, you’ll have to pay $226 out of pocket before Medicare covers costs. Deductibles vary by plan for Parts C and D.

  • Co-insurance: For Part B coverage, you’re generally responsible for 20% of the Medicare-approved amount for covered service once you meet your deductible. Co-insurance varies by plan for Parts C and D.

Learn More: Medicare Premiums and Tax Deductibles

What’s the difference between original Medicare and Medicare Advantage?

Original Medicare covers hospital visits and most services from doctors and other healthcare providers, as well as some preventive care and medical equipment, such as walkers. It doesn’t cover any self-administered prescription drugs. Original Medicare beneficiaries can go to any doctor or provider who accepts Medicare. There’s no yearly limit on the amount you pay out of pocket.

Medicare Advantage is private insurance that must offer the same coverage as Original Medicare, but often also includes prescription drugs, vision, hearing, and dental, none of which are covered by Original Medicare. Medicare Advantage patients generally must go to in-network providers. Plans must have a yearly out-of-pocket limit on services offered by Original Medicare.[11]

See Also: The Difference Between Medicare and Medicaid Explained

Medicare coverage FAQs

Find answers to some of the most common questions beneficiaries have about Medicare eligibility.

  • Can you start Medicare before age 65?

    You may be able to start Medicare before you turn 65 if you receive Social Security disability insurance (SSDI) benefits. You may receive SSDI benefits due to a disability, ALS, or an End-Stage Renal Disease diagnosis.

  • When is the Medicare enrollment period?

    Medicare has multiple enrollment periods, including initial, general, special, and open enrollment periods. Your seven-month initial enrollment period around when you turn 65 is typically the best time to enroll. Missing this enrollment period could result in a late enrollment penalty.

  • What’s the difference between Medicare and Medicaid?

    Medicare is federal health insurance offered to all citizens over the age of 65. Medicaid is a program run jointly by the federal government and state governments that offers help with medical expenses for people with limited income or resources. While Medicare does require beneficiaries to pay a premium for Part B, Medicaid generally doesn’t require a premium or other payments for most covered services.[12]

  • Should you sign up for Medicare during the initial enrollment period?

    The initial enrollment period is the best time to sign up for Medicare. Missing this period may result in a late enrollment fee.

  • When should you contact Social Security if you want to start Medicare at 65?

    You can contact Social Security as early as three months prior to the month you turn 65. If you enroll in Medicare anytime during those three months, you’ll have Medicare coverage starting on the first day of the month when you turn 65.


  1. Medicare.gov. "When does Medicare coverage start?."
  2. Medicare,gov. "Avoid late enrollment penalties."
  3. Medicare Interactive. "Medicare eligibility for those under 65."
  4. Medicare.gov. "What does Medicare cost?."
  5. Centers for Medicare & Medicaid Services. "It’s time to choose your Medicare coverage."
  6. Medicare.gov. "“Welcome to Medicare” package (not automatically enrolled)."
  7. Medicare.gov. "Joining a plan."
  8. Medicare.gov. "When can I buy Medigap?."
  9. Medicare.gov. "Parts of Medicare."
  10. Centers for Medicare and Medicaid Services. "2023 Medicare Costs."
  11. Medicare.gov. "Compare Original Medicare & Medicare Advantage."
  12. U.S. Department of Health & Human Services. "What’s the difference between Medicare and Medicaid?."
Emily Guy Birken
Emily Guy Birken

Emily Guy Birken is a former educator, lifelong money nerd, and a Plutus Award-winning freelance writer who specializes in the scientific research behind irrational money behaviors. Her background in education allows her to make complex financial topics relatable and easily understood by the layperson.

Her work has appeared on The Huffington Post, Business Insider, Kiplinger's, MSN Money, and The Washington Post online.

She is the author of several books, including The 5 Years Before You Retire, End Financial Stress Now, and the brand new book Stacked: Your Super Serious Guide to Modern Money Management, written with Joe Saul-Sehy.

Emily lives in Milwaukee with her family.

Katie Powers
Edited byKatie PowersAuto and Life Insurance Editor
Photo of an Insurify author
Katie PowersAuto and Life Insurance Editor
  • Licensed auto and home insurance agent

  • 3+ years experience in insurance and personal finance editing

Katie uses her knowledge and expertise as a licensed property and casualty agent in Massachusetts to help readers understand the complexities of insurance shopping.

Featured in

media logomedia logo

Latest Articles

View all