Breaking Down the Medicare Enrollment Calendar Month by Month

Enrolling in Medicare or changing Medicare plans is not hard but knowing when you can do it can be confusing. There are a number of Medicare enrollment periods throughout the year but only a few that may apply to your situation. This calendar will help you to keep them straight.

Calendar and hourglass
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Initial Enrollment Periods

First and foremost, you have to understand your Initial Enrollment Period (IEP). This is when you first apply for Medicare. Your IEP dates will vary based on your personal circumstances. Missing your IEP could result in your having to pay late penalties.

  • Based on age: You are eligible for Medicare when you turn 65 years old. Your IEP begins three months before and ends three months after the month you turn 65.
  • Based on employer-sponsored health coverage: If you are 65 years old and have health coverage through an employer who hires at least 20 full-time employees, a Special Enrollment Period begins the month after you leave your job or lose that health coverage—whichever comes first—and lasts for eight months.
  • Based on end-stage renal disease (ESRD): Even if you don’t enroll in Medicare as soon as you’re eligible because of ESRD, once you do enroll, you’re eligible for up to 12 months of retroactive ESRD coverage.
  • Based on Social Security Disability Insurance (SSDI): You are eligible for Medicare after receiving SSDI benefits for 24 months. The Social Security Administration will automatically enroll you in Medicare after 24 months.

If you miss your IEP, you will have to wait to enroll for Medicare during the next General Enrollment Period.

General Enrollment Period

January 1 - March 31

If you missed your Initial Enrollment Period, this is when you can sign up for Part A, Part B, or both. However, be aware that this could leave you months without coverage. As of 2022, your Medicare benefits would not begin until July 1. However, CMS has proposed a new rule that could change that starting on January 1, 2023. Anyone using the General Enrollment after that date would start to received benefits the month after they signed up.

Take note that you cannot select a Medicare Advantage plan (Part C) or a Part D prescription plan at this time. You will have to wait until the Special Enrollment Period to add prescription drug coverage.

Medicare Advantage Open Enrollment Period

January 1 - March 31

There used to be a Medicare Advantage Disenrollment Period from January 1 through February 14. During that time, you could drop your Medicare Advantage plan and change over to Original Medicare. You could also pick a Part D plan to supplement your new Original Medicare (Part A and Part B) coverage. What you could not do is change from one Medicare Advantage plan to another or change from one Part D plan to another.

In 2019, this was replaced by the Medicare Advantage Open Enrollment Period. This new enrollment period runs from January 1 through March 31. This is what you are able to do:

  • You can change your Medicare Advantage plan to Original Medicare.
  • You can add a Part D plan if you changed to Original Medicare during this enrollment period.
  • You can add a Part D plan to a stand-alone Medicare Advantage plan (a Medicare Advantage plan that does not have a Part D prescription plan included).
  • You can switch from one Medicare Advantage plan to another.

You can take advantage of the Medicare Advantage Open Enrollment Period only if you are already on a Medicare Advantage plan. You can use it only once per year, i.e., you cannot make a change in January and then make another change in March.

Special Enrollment Periods for Part A and Part B

There is not currently a Special Enrollment Period for Original Medicare (Part A and Part B), though CMS has recently proposed one. In April 2022, they recommended Special Enrollment Periods for the following circumstances:

  • An emergency or disaster, declared by your federal, state, or local government, caused you to miss your Initial Enrollment Period.
  • You are no longer eligible for Medicaid.
  • You are released from incarceration.
  • You did not sign up for Medicare during your Initial Enrollment Period because you were given inaccurate information by your employer or current health plan.
  • You have a unique situation that affected your Medicare enrollment. These "exceptional conditions" would be looked at on a case-by-case basis.

It is not clear when these Special Enrollment Periods, if approved, would take effect.

Special Enrollment Periods for Medicare Advantage and Part D

If you signed up for Medicare during the General Enrollment Period, this is when you can sign up for a Part D plan. You may also enroll in a Medicare Advantage plan with Part D coverage, an MA-PD plan. You cannot pick a Medicare Advantage plan without prescription drug coverage at this time.

There are other Special Enrollment Periods (SEPs) that relate to certain situations. These generally last two months in duration, unless otherwise stated.

SEPs based on a change in your current health plan:

  • Your government cancels its contract with your plan or vice versa.
  • You lose access to your health plan.
  • Your health plan no longer offers creditable coverage.
  • Your Medicare Advantage plan cancels its contract with the government. This has specific calendar dates, December 8 to February 28/29.

SEPs based on your coverage by one of these health plans:

  • Extra Help
  • Medicaid
  • Program of All-Inclusive Care for the Elderly (PACE)
  • State Pharmaceutical Assistance Program (SPAP)
  • Veteran’s benefits

SEPs based on where you live:

  • You are released from prison.
  • You move back to the United States from a foreign country.
  • You move into a skilled nursing facility or a long-term care hospital.
  • You move outside of your Medicare Advantage plan’s coverage area.

Open Enrollment Period

October 15 - December 7

This enrollment period is available to everyone on Medicare. During this time you can change from Original Medicare with or without a Part D plan to a Medicare Advantage with or without prescription drug coverage and vice versa. You can also sign up for, cancel or change Part D plans.

Five Star Enrollment Period

December 8 - November 30

If you want to sign up for a Five-Star Medicare Advantage plan or a Part D plan, you can do so from December 8 after the plan earns its Five-Star rating to November 30 of the following year. You have the option of doing this only once a year. If you want to leave the Five-Star plan for any reason, you will have to wait until the open enrollment period to do so.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Medicare & Medicaid Services. Medicare & you 2022.

  2. Centers for Medicare & Medicaid Services. Medicare coverage of kidney dialysis & kidney transplant services.

  3. Social Security Administration. Medicare.

  4. Centers for Medicare & Medicaid Services. Implementing Certain Provisions of the Consolidated Appropriations Act, 2021 and other Revisions to Medicare Enrollment and Eligibility Rules (CMS-4199-P). April 22, 2022.

  5. Centers for Medicare & Medicaid Services. Joining a health or drug plan.

  6. Centers for Medicare & Medicaid Services. Special circumstances (Special Enrollment Periods).

By Tanya Feke, MD
Tanya Feke, MD, is a board-certified family physician, patient advocate and best-selling author of "Medicare Essentials: A Physician Insider Explains the Fine Print."