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Medicare Supplement Open Enrollment: When to Enroll and How to Get Guaranteed Approval

 

Reviewed by Russell Noga, Licensed Medicare Insurance Broker (all 50 states) — Last updated October 21, 2026

Key Takeaway

Your Medicare Supplement Open Enrollment Period is a one-time, 6-month window. Apply during it and no insurance company can turn you down or charge you more because of your health.

Timing is the most important part of buying a Medicare Supplement plan, also called Medigap. Enroll at the right time and you can choose any plan from any company. Wait too long and your health can decide whether you are approved. This guide explains when your open enrollment starts, what happens if you miss it and the special rights that can still protect you.

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When Is Medicare Supplement Open Enrollment?

Medicare Supplement open enrollment timeline: a 6-month window starting the first month you are 65 or older and enrolled in Part B

Your Medigap Open Enrollment Period lasts 6 months. It starts the first month you are both 65 or older and enrolled in Medicare Part B.

Starts

✔First month you are 65 or older
✔And enrolled in Part B
✔Automatic, no sign-up needed

Lasts

✔6 full months
✔Happens only once
✔Cannot be restarted

During the Window

✔Buy any plan sold in your state
✔No health questions
✔Best prices available

Good to know: If you are turning 65, many insurance companies let you apply up to 6 months before your Part B start date, so your plan begins the same day as Medicare.

Why Open Enrollment Matters

During your open enrollment window, Medicare Supplement plans are guaranteed issue. After it ends, most states let insurance companies use medical underwriting.

During Open Enrollment After Open Enrollment
Health questions No Usually yes
Can be turned down No Yes
Price based on health No Can be
Plan choice Any plan, any company Only what you qualify for

Don’t wait: If you have a health condition, missing this window can mean paying more or being declined for the plan you want. Apply during your 6 months.

Once you know your timing, compare all 10 Medicare Supplement plans and see what Medicare Supplement plans cost in your area.

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If You Delay Part B Because of Work Coverage

If you keep health coverage from your own or your spouse’s current job past 65, you may delay Part B. Your Medicare Supplement open enrollment does not start until Part B does.

✔
Your 6-month window starts the month your Part B begins
✔
Retiree coverage and COBRA are different, so check before you delay Part B
✔
Plan your Part B start date so your Medicare Supplement plan begins without a gap

Guaranteed Issue Rights Outside Open Enrollment

Medicare Supplement guaranteed issue rights: when you can buy a Medigap plan without health questions, within 63 days

Even after your open enrollment ends, certain situations give you the right to buy a Medicare Supplement plan without health questions. You usually have 63 days after your other coverage ends.

✔
Your Medicare Advantage plan leaves your area or stops offering coverage
✔
You lose employer or union coverage that paid after Medicare
✔
You joined Medicare Advantage when you first turned 65 and want to switch to Medigap within the first 12 months (your trial right)
✔
You dropped a Medicare Supplement plan to try Medicare Advantage for the first time and want to switch back within 12 months
✔
Your Medicare Supplement company goes bankrupt or misled you

Which plan letters you can buy with a guaranteed issue right depends on the situation and your state. Some states offer more protection than federal law.

State Rules That Can Help

Some states give you extra chances to buy or switch Medicare Supplement plans without health questions. Whenever you switch, the Medicare Supplement free look period gives you 30 days to review your new policy.

Birthday Rules

✔California, Oregon and Illinois, among others
✔Switch plans around your birthday each year
✔Usually to equal or lesser coverage

Year-Round Access

✔New York and Connecticut
✔Buy a plan any time of year
✔No health questions

Under 65 Protections

✔Many states require sales to people under 65
✔Rules vary by state
✔Prices can be higher

State rules change. A licensed insurance agent can tell you exactly what applies where you live.

Medigap Is Not Part of the Fall Enrollment Period

The Medicare Annual Enrollment Period, October 15 to December 7, is for changing Medicare Advantage and Medicare Part D plans. Medicare Supplement plans do not have a yearly enrollment window.

✔
You can apply for a Medicare Supplement plan any month of the year
✔
Outside open enrollment, approval may depend on your health
✔
Your Part D drug plan can only change during the fall window in most cases

How to Enroll in a Medicare Supplement Plan

1
Enroll in Medicare Part A and Part B. You need both to buy a Medicare Supplement plan.
2
Mark your 6-month window. It starts the first month you are 65 or older and enrolled in Part B.
3
Choose your plan letter. Plan G, Plan N and High-Deductible Plan G are the most common choices for new enrollees.
4
Compare insurance companies. Start with the best Medicare Supplement companies, since the same plan can cost very different amounts.
5
Apply and review your policy. You have a 30-day free look period to cancel for a full refund.

The Bottom Line

Your open enrollment window comes once, and it gives you the most choices at the best prices. A licensed insurance agent at MedigapWise can help you pick a plan and apply before your window closes, at no cost.

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Medicare Supplement Open Enrollment — Frequently Asked Questions

➤ When is Medicare Supplement open enrollment?

Your Medicare Supplement Open Enrollment Period is the 6 months that start the first month you are both 65 or older and enrolled in Medicare Part B. It happens once, and it is the best time to buy a plan.

➤ Can insurance companies turn me down during open enrollment?

No. During your Medigap Open Enrollment Period, insurance companies must sell you any Medicare Supplement plan they offer in your state, and they cannot charge you more because of your health.

➤ Is there an annual open enrollment for Medicare Supplement plans?

No. Medicare Supplement plans do not have a yearly enrollment window. The fall Annual Enrollment Period, October 15 to December 7, is for Medicare Advantage and Part D, not Medigap. You can apply for a Medicare Supplement plan any time of year.

➤ What happens if I miss my Medicare Supplement open enrollment?

You can still apply, but in most states the insurance company can ask health questions. Based on your answers, it can approve you, charge you more or turn you down, unless you have a guaranteed issue right.

➤ What if I delay Part B because I have coverage from work?

Your Medigap Open Enrollment Period does not start until you enroll in Part B. If you keep employer coverage past 65 and sign up for Part B later, your 6-month window starts then.

➤ What are guaranteed issue rights?

Guaranteed issue rights are special situations, like losing employer coverage or a Medicare Advantage plan leaving your area, when insurance companies must sell you certain Medicare Supplement plans without health questions. You usually have 63 days after your other coverage ends to use them.

➤ Can I switch Medicare Supplement plans after open enrollment?

Yes, you can apply to switch at any time. Outside your open enrollment window or a guaranteed issue right, you may need to answer health questions. Some states, like California, Oregon and Illinois, have yearly birthday rules that make switching easier.

➤ Can I get a Medicare Supplement plan if I am under 65?

Federal law does not require insurance companies to sell Medicare Supplement plans to people under 65 on Medicare due to a disability, but many states do. Availability and prices depend on your state.

➤ Is there a waiting period for pre-existing conditions?

Sometimes. During open enrollment, a company can delay coverage of a pre-existing condition for up to 6 months if you did not have other health coverage before. Prior creditable coverage can shorten or remove that waiting period.

➤ Does it cost anything to get help enrolling with MedigapWise?

No. Our licensed insurance agents help you compare plans and apply at no cost, your premium is the same as buying directly from the insurance company, and you are never required to enroll.

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