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Medicare Supplement Enrollment Periods

Unlike some of the other parts of Medicare, you can enroll in a Medicare supplement (or change your current supplement) at any time. That being said, some times are better than others.

Open Enrollment Period

Your Medicare Supplement Open Enrollment Period is a 7-month window around your 65th birthday. It starts three months before your birthday month and ends three months after. For example, if your birthday is on May 12, your IEP runs from February 1 to August 31. During this time, you’ll be able to enroll in Parts A and B of Original Medicare and any other Medicare-related plans such as a Medicare supplement.

Your Open Enrollment Period gives you guaranteed issue rights to any Medicare supplement you want. You’ll be able to choose any of the ten plans and any insurance company you want, and you are guaranteed access to that plan. (The exception to this is Plan F, which limits enrollment to those who turned 65 before January 1, 2020.)

You won’t need to pass medical underwriting during this time, and the insurance carrier can’t charge you higher premiums due to your health history.

The same guaranteed issue rules apply to individuals who postpone Medicare enrollment. For example, many people are working past the age of 65 and stay on their employer-sponsored plan. As long as that plan was creditable, they’ll have guaranteed issue rights to a Medicare supplement when they lose their employer coverage.

Guaranteed Issue Situations

There are other times when you’ll have guaranteed issue rights, but with some limitations.

If you choose to enroll in Medicare Advantage (Part C), you will have a Trial Right for your first year of enrollment. That means that if you decide that you want to switch to a Medicare supplement within that first year, you’ll have guaranteed issue rights. However, which Medicare supplement you’ll have the right to will depend on various factors like your birthday and if you had a Medicare supplement before trying Medicare Advantage.

Other times when you might find yourself with guaranteed issue rights include your Medicare SELECT or Medicare Advantage plan moving from the service area, your insurance company breaking Medicare rules, or your carrier going bankrupt.

State-Specific Medicare Open Enrollments

A handful of states have their own rules around when you can enroll in a Medicare supplement without undergoing medical underwriting.

Map of state specific rules regarding Medicare Supplement Enrollment Periods

Birthday Rule States

Six states allow you to change your Medicare supplement without underwriting each year around your birthday. The enrollment windows range from 31 days to 91 days. You can use this time to enroll in the same plan (but with a different company) or a plan that provides less coverage (like switching from Plan F to Plan G).

The six states with birthday rules are:

  • California

  • Idaho

  • Illinois

  • Nevada

  • Oregon

  • Louisiana

Year-Round Open Enrollment States

Four states allow you to enroll in a Medicare supplement without underwriting at any time of the year, regardless of your age. 

The four states with year-round open enrollment are:

  • New York

  • Connecticut

  • Vermont

  • Washington

Missouri Anniversary Rule

In the state of Missouri, you can switch to a Medicare Supplement plan of equal or lesser coverage without health questions, during your last month of coverage on your existing policy.

For example, you started your Plan G coverage on February 1, 2020. Your policy will automatically renew on February 1, 2021. In Missouri, you have the entire month of January 2021 to enroll in a Plan G, Plan N, or one of the less popular Medicare Supplements, without health questions.

Maine Annual Open Enrollment

In the state of Maine, each insurer must designate a one-month period where any applicant will be accepted into a Medicare Supplement Plan A. Insurers are not required to offer the popular Plan G and Plan N during this period. 

In Maine, you also have the right to change Medicare Supplement plans as long as you switch to a plan with the same or lesser benefits. This could be going from Plan G to another Plan G or going from Plan G to a Plan N. Under these circumstances, insurers cannot deny you coverage, as long as you haven’t had a gap in your Medicare supplemental coverage of more than 90 days since your Open Enrollment Period.


Sylvia Gordon, aka Medicare Mama, is an expert on all things Medicare and Social Security. She is the 2nd Generation here at The Medicare Family and has served on the advisory boards of major insurance companies like UnitedHealthcare®, Cigna, and Anthem. In her free time, she can be found taking care of her animals (dogs, goats, peacocks, chickens), and reading a good book. Learn More.

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