Medicare Supplement Open Enrollment vs Guaranteed Issue 2027: Key Differences and When Each Applies

Reviewed by Russell Noga, Licensed Medicare Insurance Broker (all 50 states) — Last updated October 27, 2026

Both terms promise the same thing: a Medicare Supplement (Medigap) company has to sell you a policy, no matter your health. But one is a window everyone gets once, and the other only opens when something happens to your coverage.

Here’s how Medicare Supplement open enrollment and guaranteed issue rights compare for 2027, and what happens if you miss both.

Both protections stop a company from turning you down or charging you more because of your health. The difference is who gets them, when and what you can buy.

If you’re still deciding when to apply, start with our main guide to Medicare Supplement open enrollment.

Your Medigap open enrollment period lasts 6 months. It starts the first day of the month you’re both 65 or older and enrolled in Medicare Part B. It happens once and can’t be repeated.

During those 6 months, you can buy any Medigap policy sold in your state. The company can’t use medical underwriting to deny you, and it generally can’t charge you more because of past or present health problems.

Guaranteed issue rights, also called Medigap protections, apply only in limited situations. When one applies, the company must sell you a policy, must cover all your pre-existing conditions and can’t charge you more because of your health.

Under federal law, you generally have a guaranteed issue right when:

Moving out of a Medicare SELECT policy’s service area also counts. For the first-year rules, see our guide to the Medigap trial right.

The biggest difference is plan choice. Open enrollment lets you buy Plan N or any plan sold in your state; guaranteed issue limits you to Medicare’s list, though Plan G is on it. Compare every plan letter in our guide to Medicare Supplement plans.

For most guaranteed issue rights, you must apply no later than 63 days after your old coverage ends. When employer coverage ends or your Medigap company fails, Medicare counts from the latest of:

If you’re leaving Medicare Advantage, you can apply as early as 60 days before that coverage ends.

Federal law doesn’t require companies to sell Medigap to people under 65 who have Medicare because of a disability or End-Stage Renal Disease. KFF counts 38 states that do require at least one policy for people under 65 with disabilities (October 2026). At 65, you still get your own open enrollment period.

Some states also go further than federal law for people 65 and older:

State rules change, so check with your State Insurance Department before you drop a policy.

Outside both, most companies use medical underwriting and can decline you or charge more. See our guide to Medigap underwriting questions.

Illustrative example: Tom turned 65 in 2025, joined Part B and skipped Medigap because he felt healthy. In 2027, at 67, he’s diagnosed with cancer and wants Plan G. With no qualifying event, a company can decline him.

If Tom is declined and stays on Original Medicare alone, he pays 20% of most Part B costs, with no yearly limit. On a hypothetical $60,000 in outpatient treatment, that’s about $12,000 out of his pocket. Figures are illustrative only. Learn more about Medicare Supplement and pre-existing conditions.

Ready to apply? Our guide on how to sign up for Medigap walks through the application.

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