Understanding Medicare’s Initial Enrollment, General Enrollment, Open Enrollment, and Special Enrollment Periods

Medicare has a number of different enrollment periods. Initial enrollment, general enrollment, open enrollment, and special enrollment all have unique rules and dates.

Medicare Enrollment Dates

Aside from an initial enrollment period which happens when a person first gets access to Medicare, the following are the key dates each year for Medicare enrollment:

  • Jan 1 – Mar 31 (General Enrollment): If you missed initial enrollment, and you don’t qualify for a special enrollment period, you can sign up for original Medicare (Parts A and B, not Medicare Advantage). You can also change from one Medicare Advantage plan to an another, or you can drop your Medicare Advantage plan and return to Original Medicare Parts A and B.
  • April 1 – June 30: If you enrolled in Medicare part B from Jan 1 to Mar 31 you can add a Part D drug plan or a Medicare Advantage Plan during this period.
  • Oct 15 – Dec 7 (Open Enrollment): You can freely make changes to your coverage. For example, you can switch back and forth between Original Medicare and Medicare Advantage, switch back and forth between an Advantage plan that offers drug coverage and one that doesn’t, and/or you can add or drop Part D coverage.

Different Types of Medicare Enrollment Periods

In general, each part of Medicare is subject to different enrollment periods and each enrollment period typically has an official name. Here are the details on each type of Medicare enrollment period.

  1. Initial Enrollment Period: The first time you can enroll in Original Medicare Parts A and B. For most people it is the 7 months surrounding your birthday. You can enroll in Part C, Part D, and Medigap during this time as well.
  2. Open Enrollment Period: The time of year you can freely make changes to your coverage. Open enrollment lasts from Oct 15 to Dec 7 each year.
  3. Special Enrollment Period: A special enrollment period for one or more parts of Medicare can occur based on certain circumstances (for example after an employer health plan ends).
  4. General Enrollment Period: If you miss your Initial Enrollment Period or your Special Enrollment Period, you can still enroll in Parts A and B from Jan 1 to Mar 31 each year.
  5. Medicare Advantage Open Enrollment Period: Medicare Advantage has two open enrollment periods. The first is Oct 15 to Dec 7, it is part of Medicare’s open enrollment period. The second is a limited enrollment and disenrollment period. This limited enrollment period goes from Jan 1 to Mar 31 each year and is a time when you can change from one Medicare Advantage plan to an another or drop your Medicare Advantage plan and return to Original Medicare Parts A and B.
  6. Limited Enrollment For Part C and Part D: If you enrolled in Medicare part B from Jan 1 to Mar 31 you can add a Part D drug plan or a Medicare Advantage Plan from April 1 to June 30.
  7. Medigap Protected Enrollment Period: You can enroll in Medigap at any time, but it is only guaranteed issue for a 6 month period starting the month you are 65 or older and enrolled in Medicare Part B.

TIP: Missing an enrollment period can mean paying penalties or in some cases not even being able to obtain the coverage you want.