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Medicare Enrollment Periods

enrollment periodsIf you’re eligible (or soon to be eligible) for Medicare, you may have noticed that there are specific times when you can enroll, add, change or drop coverage. These enrollment periods can be confusing! There are so many different enrollment periods and each has different rules. In this article we’ll attempt to make the enrollment periods a bit less confusing.

Initial Enrollment Period

When you first reach age 65 and become eligible for Medicare benefits, there is a set period of time when you can enroll. The initial enrollment period actually begins before your 65th birthday, and is a total of seven months. This includes the three months before your month of birth, the month that you reach age 65, and the three months after your birth month. So if your 65th birthday is in July, your initial enrollment period starts on April 1 and lasts until October 31.

During this period you can enroll in Medicare Part A and Part B. You can then choose other additions to your Medicare coverage, including prescription drug coverage, a Medicare supplement policy (Medigap), or maybe a Medicare Advantage plan.

The month in which you enroll determines when your Medicare Part B coverage will begin. If you enroll in Medicare during the any of the 3 months prior to your 65th birthday, your coverage will begin during the month of your birthday. If you enroll during your birthday month, coverage begins on the first of the following month. If you enroll in the month after your 65th birthday, coverage is delayed until the first of the month that is two months after your birthday. If you wait to enroll during any of the remaining 2 months in your initial enrollment period, there will be a three-month lag before your benefits will begin. For example, if your birth month is July and you wait until August to enroll for Medicare, your Part B coverage will not commence until October 1. If you enrolled in September, the coverage would not begin until December 1.

Medicare Part A is different. Your coverage begins on the first of the month when you reach age 65, even if you enroll up to 6 months after your birthday. Beyond 6 months after your birthday, Medicare coverage always begins retroactively 6 months before the date that you enroll.

Delaying enrollment in Medicare Part A until some time after your initial enrollment period carries no penalty (unless you’re not eligible for “free” Part A). However, delaying Medicare Part B enrollment until after the initial enrollment period can result in premium penalties.

Medigap Initial Enrollment Period

Once you have enrolled in Medicare Part B, you have a 6-month period when you can enroll in Medigap. Generally, if you do not purchase a Medigap plan during this period, you may be required to provide evidence of insurability to the insurance provider if you attempt to purchase a policy later. This may result in higher premiums or denial of coverage altogether, if there is a pre-existing condition.

During the 6 months after Medicare Part B enrollment, insurers are required to accept you as an enrollee in whatever Medigap Plan you choose, as long as you can pay the premiums.

You can also make changes to your Medigap plan on an annual basis, however, as noted elsewhere, making changes to your Medigap plan may require additional information about your medical history, especially if changing to a more comprehensive plan. Choosing a less comprehensive plan typically does not cause any issues.

Annual Enrollment Periods

There are several annual enrollment periods that you need to be aware of. There is the General Enrollment Period, the Open Enrollment Period, and the Medicare Advantage Open Enrollment Period. These are explained briefly below:

General Enrollment Periods – This is from January 1 to March 31 each year. During this period you are allowed to enroll in Medicare Part B if: 1) you didn’t sign up when you were first eligible during your initial enrollment period; and 2) you aren’t eligible for a Special Enrollment Period. You can always sign up for Medicare Part A at any time, with no penalty.

When you sign up for Medicare Part B during the General Enrollment Period, most often you will pay a penalty on your premiums for Medicare Part B. There is no penalty for signing up for Medicare Part A late if you’re eligible for the “free” coverage. If less than a year has passed since your initial enrollment period, you may not have a penalty for your late enrollment.

Your Medicare Part B coverage will not begin until July 1 of the year that you sign up during the General Enrollment Period. Medicare Part A coverage is back-dated to six months prior to your enrollment date, or the month of your 65th birthday if you enroll less than six months after that date.

If your enrollment in Medicare Part B is completed during the General Enrollment Period, you will then have an opportunity to acquire a Medicare Advantage plan or add a Medicare Part D plan to your coverage during the period between April 1 and June 30 of that same year. If you do not add these items during that period, you must wait until the following fall’s Open Enrollment Period (see below) if you want to add or make changes to your plan(s).

Medicare Advantage Open Enrollment Periods – In addition, during this same period from January 1 through March 31 each year, you can change from one Medicare Advantage plan to another. You can only make this change during this period if you are currently have a Medicare Advantage plan. You can also make the switch from Medicare Advantage to original Medicare (Part A and Part B, with or without Part D and/or Medigap) during this period.

You cannot switch from original Medicare to a Medicare Advantage plan during this period. That is only allowed during the fall Open Enrollment Period (covered next).

Open Enrollment Periods – this period is also known as the “fall open enrollment period”, because it’s the only period that occurs during the fall (all others are in the first part of the year). From October 15 to December 7 each year, you are allowed to make several changes to your healthcare coverage. This is the period that allows the most flexibility in changing up your overall Medicare coverage landscape.

During this period, you can switch from original Medicare (Part A and Part B) to a Medicare Advantage plan. You can also do the reverse – switching from a Medicare Advantage plan back to original Medicare (Part A and Part B).

You may also switch your coverage from one Medicare Advantage plan to another Medicare Advantage plan. The plan you choose may or may not have prescription drug coverage. So you may also add a Medicare Part D (prescription drug coverage) plan to your coverage at this time. You can switch from one Part D plan to another during this period, or you can drop your Part D coverage.

If dropping Medicare Part D coverage, you can either choose to go without prescription drug coverage, or you can add a Medicare Advantage plan that includes prescription drug coverage.

Special Enrollment Periods

Medicare Part B Enrollment Period – If you (or your spouse, or other family member if you’re disabled) are working and you’re covered by a group health plan through your, your spouse’s or family member’s employer or union based on that work, you may have a Special Enrollment Period when that coverage ends. This special enrollment period is available when there has been a change to your situation regarding the creditable coverage.

Your Special Enrollment Period includes the entire time from your 65th birthday and are employed and covered by a creditable health plan, plus 8 months after your coverage ends. The 8 months begins the month after the employment ends, or the month after the group health plan based on the employment ends. These are the two changes that typically occur that allow for a special enrollment period. Another situation that provides a special enrollment period is divorce from or death of a spouse or family member whose employment was providing creditable coverage.

Additionally, a Special Enrollment Period may be available to you if you discontinued Medicare Part B because you started being covered by an employer plan (either your own or your spouse’s). When that coverage comes to an end, you have 8 months to enroll again in Medicare during the Special Enrollment Period. Otherwise you’ll have to wait until an annual enrollment period and likely be assessed a penalty for late enrollment.

You will not be assessed the late enrollment penalty for either paid Medicare Part A or Medicare Part B if you’re eligible for a special enrollment period and you enroll during the applicable period. Delay past the end of the special enrollment period will cause the same kinds of penalties to apply as if you delayed enrollment until some time after your initial enrollment period.

It is important to note that COBRA and retiree health insurance are not considered as creditable coverage that would allow you to utilize a Special Enrollment Period. Only active employee health insurance is allowed to provide for this special treatment. Furthermore, COBRA coverage coming to an end (COBRA provides coverage for up to 18 months after employment has ceased) is NOT an event that starts a Special Enrollment Period. Only the original plan coming to an end or the end of employment will trigger the Special Enrollment Period.

If you sign up for Medicare Part B while you are still covered by the employer plan, or during the first full month that you no longer have coverage from your employer, Medicare Part B coverage begins on the first day of the month that you enroll. You can choose to delay this coverage to begin with any of the succeeding three months after enrollment.

If you wait until any of the remaining 7 months of your Special Enrollment Period to enroll in Medicare Part B, coverage will begin on the first day of the month after you’ve enrolled.

The coverage delays when signing up during a Special Enrollment Period are much less than the 6-month delay with the Annual Enrollment Period, because the AEP signifies a period of time when you did not have creditable coverage but were eligible for Medicare coverage. Any time there has been a gap in coverage, insurers require a delay before coverage to allow for any adverse conditions that may have commenced.

Special Enrollment Period for Medicare Advantage and Part D – For a Medicare Advantage plan and Medicare Part D, the Special Enrollment Period lasts only two months after your employer or group health plan has ended. Your coverage begins on the first of the following month after you enroll.

In addition to the Special Enrollment Period that is available when you have left your employer or your employer health plan has terminated, there are several other conditions that may provide for a Special Enrollment Period. Many of these conditions only apply to either Medicare Part D and/or Medicare Advantage plans. This is a reflection on how fluid the prescription drug coverage landscape can be.

Below is a list of the circumstances that Medicare has developed that may provide you with a Special Enrollment Period. For more details on the periods, please go to Medicare’s website ( and search for “special enrollment period”.

  1. You have creditable drug coverage or lose creditable coverage through no fault of your own
  2. You choose to change employer/union coverage (through either current or past employment)
  3. You are institutionalized
  4. You are enrolled in a State Pharmaceutical Assistance Program (SPAP)
  5. You have Extra Help, Medicaid, or a Medicare Savings Program (MSP)
  6. You gain, lose, or have a change in your Medicaid, MSP, or Extra Help eligibility status
  7. You want to disenroll from your first Medicare Advantage Plan
  8. You enroll in/disenroll from PACE (Program of All-Inclusive Care for the Elderly)
  9. You move (permanently change your home address)
  10. You have had Medicare eligibility issues
  11. You are eligible for a Special Needs Plan (SNP) or lose eligibility for your SNP
  12. You are passively enrolled into a Part D plan or Dual-eligible SNP (D-SNP)
  13. You experience contract violations or enrollment errors
  14. Your plan no longer offers coverage
  15. You disenroll from your Medicare Advantage Plan during the Medicare Advantage Open Enrollment Period
  16. You qualify for a new Part D Initial Enrollment Period when you turn 65
  17. You want to enroll in a five-star Medicare Advantage Plan or Part D plan
  18. You have been in a consistently low-performing Medicare Advantage or Part D plan
  19. Your Medicare Advantage Plan terminates a significant amount of its network providers
  20. You experience an “exceptional circumstance”

As noted above, the Special Enrollment Period for Medicare Advantage plans and Medicare Part D plans only lasts for two months after your employer-provided or group insurance plan has ended. This one can pass by in a hurry, you need to pay close attention if you need this coverage during a Special Enrollment Period.


  1. Ritch says:

    As Jack said, this is an excellent explanation of a very convoluted subject. Thanks for sharing it.

    The article does have an omission, which I’d like to ask if you would correct (or complete).

    Here’s the text in Paragraph # 10 above.
    “There are several annual enrollment periods that you need to be aware of. There is the General Enrollment Period, the Open Enrollment Period, and These are explained briefly below:”

    Would you please consider adding the missing text after the word “and” above?

    I believe you intended to add Special Enrollment Period, but I don’t want to assume that without asking/verifying that to be the case.

    Thanks very much.

    1. jblankenship says:

      Thank you for pointing out the omission. I have corrected it, and the text added was “the Medicare Advantage Open Enrollment Period”.

  2. Jack says:

    This is absolutely the clearest and most comprehensive article on Medicare enrollment that I have seen (and I’ve read many during the last few years).

    1. jblankenship says:

      Thank you, I’m happy to hear it was useful!

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