Watch the Video
The Medigap Open Enrollment Period (OEP) is the main federal window for buying a Medicare Supplement (Medigap) policy without medical underwriting. It lasts six months and begins automatically on the first day of the month in which you are both age 65 or older and enrolled in Medicare Part B.
Need an Enrollment Checklist?
This page explains the enrollment rules. When you are ready to compare plan letters, quotes, and effective dates, use our practical Medigap enrollment checklist.
There Is No Federal Annual Medigap Open Enrollment Period
The fall Medicare Annual Enrollment Period does not reopen your original Medigap window. After the six-month period ends, medical underwriting may apply unless you have a federal guaranteed-issue right or an additional state protection.
When Does Your Medigap OEP Begin?
Your Medigap OEP begins on the first day of the month you are both 65 or older and enrolled in Part B. If you turn 65 in June and Part B starts June 1, your OEP runs June 1 through November 30. If you delay Part B while covered through current employment, your OEP generally waits until Part B begins, even if you are already older than 65.
| Scenario | Part B Start Date | OEP Window |
|---|---|---|
Turn 65 in June, enroll in Part B at 65 | June 1 | June 1 through November 30 |
Turn 65 in June, delay Part B until retirement at 68 | October 1 (age 68) | October 1 through March 31 (age 69) |
Receive Medicare due to disability before 65 | Varies | A new six-month OEP generally begins when you turn 65 while enrolled in Part B |
You can verify the federal rule on Medicare.gov's Medigap enrollment timing page. People under 65 may have additional Medigap rights under state law, but those rights vary.
What Protections Apply During Your OEP?
During your Medigap OEP, an insurer must sell you any Medigap policy it offers, even if you have health problems. It cannot use medical underwriting to deny you, delay your application, or charge you a higher premium because of your health history.
You can apply for any Medigap policy the insurer sells for which you are eligible
The insurer cannot deny your application because of a current or past health condition
The insurer cannot add a health-based surcharge to your premium
Your premium may still vary for non-health factors allowed under state law, such as age, location, tobacco use, or household discounts
Open Enrollment and Guaranteed-Issue Rights Are Related but Different
Your Medigap OEP is a broad six-month purchase protection tied to age and Part B. Federal guaranteed-issue rights apply in specific situations outside that window and may limit which policies you can buy.
How Do Pre-Existing Conditions Affect Coverage?
An insurer cannot deny you or charge more because of a pre-existing condition during your OEP. In limited circumstances, however, the policy may delay coverage related to that condition for up to six months. Prior creditable coverage can reduce or eliminate this waiting period, especially when you had at least six months of continuous coverage before applying.
A pre-existing-condition waiting period does not postpone the entire Medigap policy. Other covered benefits can begin on the policy effective date. Review our guide to Medigap and pre-existing conditions and ask the insurer to explain any waiting period in writing before you enroll.
Which Plans Can You Buy During Your OEP?
During your OEP, you can buy any standardized Medigap plan an insurer sells for which you are eligible. Plan G covers most Original Medicare cost sharing except the Part B deductible. Plan N can have a lower premium but includes certain copayments and does not cover Part B excess charges.
Plans C and F are available only to people who were eligible for Medicare before January 1, 2020. Massachusetts, Minnesota, and Wisconsin use different standardized plan structures, so residents should compare their state-specific options rather than relying on the standard letter-plan chart.
What Happens After Your OEP Ends?
Once your six-month OEP closes, an insurer may use medical underwriting in most states. It may ask health questions, charge more because of your health, or deny your application. Medigap has no federal late enrollment penalty, but waiting can affect your access to a policy and the price you are offered.
You may still have a federal guaranteed-issue right after certain coverage changes. Some states also offer additional protections, including birthday or anniversary rules. These rights are situation-specific, so confirm the policy choices and application deadline before ending existing coverage.
How Is Medigap OEP Different From Other Enrollment Periods?
| Enrollment period | What it controls | Does it create a new federal Medigap OEP? |
|---|---|---|
Medigap Open Enrollment Period | Your protected federal window to buy Medigap | This is the Medigap window |
Medicare Initial Enrollment Period | Initial enrollment in Medicare Parts A and B and related choices | No, but your Part B start can trigger Medigap OEP |
Medicare Annual Enrollment Period | Medicare Advantage and Part D changes from October 15 through December 7 | No |
Medicare Advantage Open Enrollment Period | Limited changes for current Medicare Advantage members from January 1 through March 31 | No |
A valid opportunity to leave Medicare Advantage does not automatically guarantee that you can buy every Medigap policy. Confirm whether a trial right, guaranteed-issue right, state protection, or medical underwriting applies before changing your Medicare Advantage coverage.
How to Enroll During Your OEP
First confirm your Part B effective date. Then compare standardized plan letters, request equivalent quotes from multiple insurers, and choose a policy effective date that coordinates with any employer, retiree, or other supplemental coverage. Medigap policies sold today do not include outpatient prescription coverage, so review a separate Part D plan if you do not have other creditable drug coverage.
Confirm your Part B effective date and the last day of any current coverage
Compare the benefits of the Medigap plan letters available to you
Request quotes using the same age, ZIP code, tobacco status, effective date, and household assumptions
Get the insurer name, policy form, premium, discount terms, and effective date in writing
Do not cancel existing coverage until the replacement policy is approved and its start date is confirmed
Can I be denied a Medigap plan during my Open Enrollment Period?
No. During your federal Medigap OEP, an insurer must sell you any Medigap policy it offers for which you are eligible. It cannot use your health history to deny the application or charge a higher premium. Non-health pricing factors allowed under state law can still affect the premium.
Can a Medigap insurer ask health questions during my OEP?
An application may include health information, but the insurer cannot use medical underwriting to deny you or charge more because of your health during your OEP. The insurer may need information to determine whether a pre-existing-condition waiting period applies, so answer application questions completely and accurately.
Does the Medigap OEP apply to Medicare Advantage plans?
No. The Medigap OEP applies only to Medicare Supplement policies used with Original Medicare. Medicare Advantage has separate enrollment periods and plan rules. You cannot use Medigap to pay Medicare Advantage cost sharing, and an opportunity to leave Medicare Advantage does not automatically create a new Medigap OEP.
What if I enrolled in Medicare Advantage first and now want Medigap?
You may have a federal trial right in certain situations, including some first-time Medicare Advantage enrollments, but the details depend on how and when you joined. Confirm the Medicare Advantage disenrollment period and your Medigap purchase protection before leaving the plan so you do not create an unexpected coverage gap.
Can I buy Medigap after my OEP ends?
Yes, you can apply, but medical underwriting may apply in most states. An insurer may deny the application or charge more because of your health unless you have a federal guaranteed-issue right or a state protection. Check your rights before cancelling any policy you already have.
Do I need to wait until October to enroll in Medigap?
No. The October 15 through December 7 Medicare Annual Enrollment Period is mainly for Medicare Advantage and Part D changes. It does not create a federal annual Medigap window. Your initial Medigap OEP is tied to being 65 or older and enrolled in Part B.
Need Help Understanding Your Medicare Options?
Our licensed Medicare experts can help you find the right coverage for your needs.