The Smartest Time to Buy a Medigap Plan (and When Waiting Can Cost You)

Missing the right window to buy a Medigap (Medicare Supplement) plan can mean higher premiums, medical underwriting, or being turned down altogether. The “best time” isn’t just about convenience — it’s built into Medicare’s rules.

Your One-Time Best Window: The Medigap Open Enrollment Period

For most people, the single best time to buy a Medigap policy is during your Medigap Open Enrollment Period. That window:

• Starts the month you are both 65 or older and enrolled in Medicare Part B
• Lasts for 6 months

During this 6‑month period:

• You cannot be denied a Medigap policy because of health problems.
• Insurers cannot charge you more based on your medical history.
• Preexisting condition waiting periods are limited if you had qualifying prior coverage.

If you buy during this time, you get guaranteed-issue rights and the broadest plan choice at the most favorable underwriting terms you’re likely to see.

Special Situations: When You Have Guaranteed-Issue Rights Later

Outside your initial 6‑month window, you may still have guaranteed‑issue rights in certain situations. These rights are time‑limited and very specific. Common examples include:

• You lose other Medicare coverage through no fault of your own (for example, your Medicare Advantage plan leaves your service area).
• You joined a Medicare Advantage plan at 65 and decide to switch back to Original Medicare within the first year.
• Your Medigap insurer goes bankrupt or ends your plan in your area.

In these cases, you usually have a short period (often 63 days from coverage loss) to enroll in certain Medigap plans without medical underwriting. The exact plans available and timelines depend on federal rules and your state.

Buying a Medigap Plan After Your Best Window

You can apply for a Medigap plan anytime of year. There is no annual enrollment season limit like Medicare Advantage or Part D. But once you are outside open enrollment or special guaranteed‑issue situations:

• Insurers can require medical underwriting.
• You may be charged more because of health conditions, or
• You may be denied coverage altogether.

If your health is still relatively good, you might still qualify at a good rate — but there is no protection guaranteeing it.

Timing Tips If You’re Planning Ahead

To make your timing work for you:

• If you’re still working past 65 and delay Part B, your 6‑month Medigap window starts when Part B begins, not at 65. Mark that date.
• If you’re moving from a Medicare Advantage plan back to Original Medicare, check whether you qualify for a trial right or other guaranteed‑issue protections.
• If you’re approaching retirement with known health issues, it is especially important to use your first open enrollment period; you may not get better terms later.

Choosing a Medigap plan is about both benefits and timing. For most people, enrolling during that first 6‑month Medigap Open Enrollment Period when Part B starts offers the widest choice, strongest protections, and the best chance to lock in coverage you can keep for the long term.