Medigap Open Enrollment is a one-time six-month window that can make buying Medicare supplement insurance easier. The window is important, but its start date is often misunderstood. It does not simply begin on your 65th birthday.

Educational note: This guide is general information, not personalized insurance advice. Rules and plan availability can depend on your circumstances and state. No 2027 premiums or plan changes are included.

What is Medigap?

Medigap is private insurance that works with Original Medicare. Medicare pays first for covered, medically necessary services, and the Medigap policy may pay some of the remaining cost sharing, depending on the plan.

You must have Medicare Parts A and B to buy Medigap. Medigap does not pay Medicare Advantage cost-sharing, and insurers generally cannot sell you a new Medigap policy while you are enrolled in Medicare Advantage. If you already have Medigap and join Medicare Advantage, ask Medicare or the insurer whether the policy should be canceled or can be suspended. Medigap generally does not include outpatient prescription drug coverage, so people who choose Original Medicare and Medigap usually evaluate a separate Part D plan. Medicare’s Medigap overview explains the relationship.

When does the six-month period begin?

For someone turning 65, the Medigap Open Enrollment Period begins on the first day of the month in which the person is both age 65 or older and enrolled in Medicare Part B. It lasts six months.

For example, if Part B starts on July 1 and the person is already 65, the six-month period begins July 1. If Part B begins later, the start date is later. Check the Part B effective date on the Medicare card and enrollment paperwork rather than counting from the birthday.

During this period, insurers generally must sell you any Medigap policy offered in your state and may not use your health history to deny coverage or charge more because of health problems. A permitted pre-existing-condition waiting period may apply in some situations, depending on your prior continuous coverage and applicable rules. Medicare explains the enrollment window.

Medigap Open Enrollment is not an annual event. It is also different from the October 15 through December 7 Annual Election Period used for Medicare Advantage and Part D changes.

What if you apply later?

After the six-month window, an insurer may be able to use medical underwriting. Depending on the situation and state rules, the insurer could charge more, impose conditions, or decline an application. There is no general federal rule that gives everyone a new Medigap Open Enrollment Period every year.

Some people have protections outside the window. A guaranteed issue right may arise after certain coverage losses or qualifying events, such as losing eligible employer or union coverage or leaving a Medicare Advantage plan in a qualifying situation. The right can be limited to certain plan letters and a specific deadline. You may need proof that coverage ended or will end.

Texas rules can add important details. Read the Texas Department of Insurance consumer resources, and confirm your individual deadline before making a change.

Choosing a plan during open enrollment

Medigap plans are standardized by letter in Texas and most states. The same plan letter generally has the same standardized benefits, but insurers can charge different premiums. Not every insurer offers every plan, and premiums can vary based on where you live and the insurer’s rating method.

Plans C and F are generally unavailable to people who first became eligible for Medicare on or after January 1, 2020. People eligible before that date may have different options. Plan G and Plan N are examples of plans with different cost-sharing designs, but a letter alone does not tell you the premium or whether the plan fits your needs. Compare plan benefits at Medicare.gov.

When comparing policies, look at:

The monthly Medigap premium and how it may change
The Part B deductible and cost sharing the plan does or does not cover
Foreign travel emergency benefits, if relevant to you
Household discounts and payment options, if offered
Whether you need a separate Part D policy
The insurer’s service record and license status

Switching from Medicare Advantage

If you are in Medicare Advantage and want Medigap, you generally must return to Original Medicare first. Returning to Original Medicare does not by itself guarantee that an insurer will sell you a Medigap policy. You may have a trial right, guaranteed issue right, or another protection depending on how and when you joined or left coverage.

Do not cancel Medicare Advantage or an existing Medigap policy until you know the new policy is approved and its effective date is confirmed. Ask Medicare or a licensed insurance professional to explain your specific enrollment and switching rights. Medicare’s Medigap rights page is the starting point.

Coverage after you buy

Medigap policies are generally guaranteed renewable. An insurer normally cannot cancel coverage because your health changes, although coverage can end for reasons such as nonpayment of premiums or intentional material misrepresentation. Premiums can increase under the insurer’s approved rating method.

If you move, ask whether your policy remains available in your new location and whether you have a right to change plans. A Medicare Select policy can have network requirements for routine care, and moving may trigger special options. Confirm the rules before changing coverage.

A simple enrollment checklist

Confirm Medicare Part B’s effective date.
Mark the six-month Medigap Open Enrollment Period on your calendar.
Compare plan letters and premiums from licensed insurers.
Check drug coverage separately through Part D or another creditable source.
Ask about pre-existing condition rules, guaranteed issue rights, and effective dates.
Verify the agent and insurer through Texas Department of Insurance consumer resources.
Keep copies of applications, notices, policy documents, and payment records.

Before you act

Confirm your Part B effective date, compare available policies, and verify any guaranteed-issue or Texas-specific rights with Medicare, the Texas Department of Insurance, SHIP, or a licensed professional.

Medigap Open Enrollment: Your Consumer Guide