What are the three enrollment periods for Medicare?

Medicare is a federal health insurance program designed to help older Americans and people with disabilities receive the healthcare they need. 

If you’re nearing the age of 65 — or you’re younger but are still eligible — you’ll need to familiarize yourself with the benefits offered through the Medicare system. While it may have a reputation for being complex, this blog will aim to demystify the Medicare process. 

In a nutshell, you have a seven-month period in which to enroll. This timeframe begins three months before your 65th birthday and extends three months past it. Here’s a simple guide to help you stay on target:

  • If you’re 64 years old: Begin your research on Medicare, utilizing resources such as those found here and here
  • If you’re 64 years and nine months: You can now enroll in Medicare (it’s three months before you turn 65). Consider enrolling now to make sure you’re covered on your 65th birthday. 
  • If you’re 65 years old: The clock is ticking, and It’s time to enroll in Medicare if you have not already done so. 
  • If you’re 65 years and three months: You must enroll by this date to avoid potential late fees. Remember that you can change plans during the annual fall open enrollment period.

Medicare Enrollment Periods Made Easy

Many people don’t realize that automatic enrollment in Medicare (Parts A and B ) only happens if you’ve been actively taking Social Security benefits at least four months before your 65th birthday. If you haven’t started taking Social Security yet, you’ll have to sign up for Medicare on your own. 

Maybe you want to know when to prepare for Medicare Annual Enrollment 2023, or you’re asking yourself, “when does Medicare Open Enrollment end?” We can help with that, so keep reading.

There are three (3) main enrollment periods for Medicare, and each has its own requirements and rules. Understanding these enrollment periods is crucial for making informed decisions about your healthcare coverage and ensuring the coverage you need when you need it.

#1: The IEP (Initial Enrollment Period)

The first enrollment period’s name is self-explanatory; it’s called the Initial Enrollment Period, or IEP, and it begins three months before the month you turn 65. Then, it ends three months after the month you turn 65, so that’s a total of seven months. 

During this time, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance). As mentioned above, you’ll automatically be enrolled if you’ve been receiving Social Security benefits for at least four months. If not, you’ll want to actively enroll during this time.


  • It begins three months before you turn 65 and lasts for seven months. 
  • During this time, you’re eligible to enroll in Medicare Part A and Part B.
  • After your Initial Enrollment Period ends, you can only sign up during one of the other enrollment periods.
  • If you miss your IEP, you may face penalties for late enrollment.

#2: The AEP (Annual Enrollment Period)

Sometimes referred to as the Annual Election Period, the Annual Enrollment Period (AEP) takes place annually from October 15th to December 7th. It’s your first opportunity to review your Medicare, Medicare Advantage, and Medicare prescription drug plans and make changes to your coverage. 

For example: 

  • If you’re enrolled in Original Medicare, you can use the AEP to switch to a Medicare Advantage plan. 
  • If you’re already enrolled in Medicare Advantage, you can use the AEP to switch to a different Medicare Advantage plan. 
  • Additionally, if you joined a Medicare Advantage plan but now want to return to Original Medicare, you can do so during the AEP.

>> What about prescription drugs?

During this time, you also have the option to enroll in or make changes to your Medicare Part D prescription drug coverage. If you’re already in a Medicare Part D plan, you can switch to a different plan, or if you receive coverage through another source, you can drop Medicare Part D without a penalty.

Any changes made during the AEP will take effect on January 1st of the upcoming year.

>> Wait, did you miss your IEP? 

If you’ve missed your initial enrollment opportunity for Medicare, you can use the AEP to enroll in a plan; however, penalties might apply.


  • It takes place from October 15th to December 7th each year. 
  • During this time, you can switch from one Medicare Advantage plan to another. 
  • You can switch from Original Medicare to a Medicare Advantage Plan or vice versa. 
  • You can enroll in the Medicare Part D drug plan or cancel your existing Medicare Part D drug plan.
  • Any changes made during AEP take effect on January 1st.

#3: The OEP (Open Enrollment Period)

Then there is a three-month period from January 1st to March 31st that’s known as the Open Enrollment Period (OEP)

Already enrolled in a Medicare Advantage plan?

  • If you missed the AEP or want to change the plan you enrolled in during AEP, you can use the Open Enrollment Period to make changes to your Medicare Advantage plan coverage.
  • If you revert to Original Medicare during OEP, you can also choose to join a Medicare Part D drug plan.
  • Plan changes will take effect on the first day of the following month after your requested change is processed.
  • Note that you can only make one change during OEP. Once a change has been made, it cannot be changed again until the next AEP.

Haven’t enrolled in Medicare yet?

  • If your Initial Enrollment Period (IEP) has come and gone — meaning you’re over 65 and three months — and you don’t qualify for a special enrollment period (more on that in the next section), you can still enroll in Original Medicare during OEP, although you may be penalized. 
  • Once you submit your application, coverage will start on the first day of the following month. 
  • It’s worth mentioning that for new enrollments, the Open Enrollment Period only applies to Original Medicare. If you want Medicare Advantage or Medicare Part D prescription drug coverage, you must wait until the next Annual Enrollment Period in October.


  • It takes place annually, from January 1st to March 31st. 
  • Changes can be made to your Medicare Advantage plan, or you can switch back to Original Medicare with a Part D prescription plan.
  • Changes made during OEP will take effect on the first day of the following month. 
  • If you missed your unique Initial Enrollment Period, you can enroll for the first time — but in Original Medicare only.

One more! The Special Enrollment Period (SEP)?

The Special Enrollment Period (SEP) allows you (if eligible) to enroll in or make changes to your Medicare coverage outside of the standard enrollment periods. You qualify for Special Enrollment Period if you have had certain life events, including:

  • Moving to a new area that does not offer your specific Medicare Advantage plan
  • Getting married, having a baby, or adopting a child
  • Getting divorced or legally separated and losing health insurance
  • Losing employer or union health coverage within the past 60 days
  • Losing drug coverage through no fault of your own
  • Becoming eligible for Medicare due to a disability
  • Having your household income drop below a specified amount
  • Becoming a U.S. citizen or re-entering the United States after living abroad
  • Qualifying for Medicaid or losing Medicaid coverage due to a decrease in income
  • Living in an area where your Medicare Advantage plan no longer services
  • Moving into or out of an institution, including skilled nursing facilities, long-term care hospitals, or prison/incarceration


  • Changes must be made within a 2-month window of an acceptable and verifiable qualifying event.
  • During this time, you can change your Medicare Advantage, switch back to Original Medicare, and enroll with (or withdraw from) Medicare prescription drug coverage. 
  • Changes made during the Special Enrollment Period will take effect on the first day of the next month.

How can we help?

Navigating these enrollment periods for Medicare is crucial for making informed decisions about your healthcare coverage and avoiding any premium adjustments and late enrollment fines. By understanding these enrollment periods, you can ensure that you’ll have the coverage you need when you need it.

That’s how we can help. Our Guided Medicare team can answer your questions about Medicare coverage, help you decide which plan is best for you, and help you with enrollment.

Speak with a Guided Medicare agent today!


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