What Is the Medigap Open Enrollment Period and Why It Matters for Your Coverage

What Is Medigap Open Enrollment?

Medigap open enrollment is the six-month period that begins when you first enroll in Medicare Part B, giving you a guaranteed-issue window to buy a Medigap policy without medical underwriting. During those six months, insurers cannot deny your application, exclude pre-existing conditions, or charge you higher premiums based on health history. This protection makes it the most important time to compare plans and enroll if you want a supplemental policy with predictable costs and simple approval. If you miss this window, you may face medical questions and waitlists later, so planning ahead matters.

When Does the Medigap Open Enrollment Period Start?

The clock starts on the first day of the month you turn 65 and enroll in Medicare Part B. It then runs for six full months, ending on the last day of the fifth month after you turn 65. For example, if your 65th birthday is July 10 and you sign up for Part B that month, your open enrollment runs until December 31. You do not need to wait for the Medicare card to arrive — eligibility is based on your Part B effective date. If you delay Part B enrollment past your initial period, your Medigap open window may also change, which can limit options and pricing later.

What Coverage Can You Get During This Period?

You can enroll in any Medigap plan the insurer offers in your state. Carriers must sell you Plan A if it is available, but they are only required to offer it. For other standardized plans, such as Plan G or Plan N, they may sell them or decline. Insurers must follow state rules and federal regulations, so it is worth checking your state's specific list of plans before you apply. Some states also have Medigap protections for people under 65 who qualify due to disability or certain conditions, but those rules differ and may not include the same six-month window.

What Happens After the Open Enrollment Period Ends?

You can still apply for Medigap coverage, but you lose the guaranteed-issue right. Insurers may ask about health history, use medical underwriting, or decline coverage entirely. Premiums can be higher, and some plans may impose waiting periods for pre-existing conditions. People who wait often turn to employer retiree coverage or private supplemental insurance as alternatives, but those options vary and may not match the cost or benefits of Medigap. If you are close to turning 65, the best time to act is before the deadline so you keep the widest choice and the most predictable pricing.