Why Medigap Plans Can Save You—or Cost You—Depending on Timing

Key Takeaways

• Medigap enrollment timing directly affects your costs, eligibility, and protection from medical underwriting in 2025.

• Missing your one-time Medigap Open Enrollment Period can lead to coverage denials or higher premiums later, depending on your health.

What Medigap Plans Are Designed to Do

Medigap, also known as Medicare Supplement Insurance, is designed to fill in the cost gaps left by Original Medicare. These plans help cover expenses such as:

• Part A and B coinsurance

• Hospital costs after Medicare benefits are exhausted

• Skilled nursing facility care coinsurance

• Part A deductible

• Emergency medical coverage while traveling abroad (varies by plan)

Medigap is not a standalone plan. You must be enrolled in Medicare Part A and Part B to purchase a Medigap policy. It does not include prescription drug coverage—so if you need drug benefits, a separate Medicare Part D plan is required.

The One-Time Medigap Open Enrollment Window

In 2025, your best opportunity to buy a Medigap plan begins the month you’re both:

• Age 65 or older

• Enrolled in Medicare Part B

This triggers your six-month Medigap Open Enrollment Period (OEP). During this time:

• You can buy any Medigap plan available in your state

• You can’t be denied coverage for any health reason

• You won’t face higher premiums due to pre-existing conditions

This is a one-time opportunity. If you miss it, you may lose your guaranteed right to purchase a plan later.

What Happens If You Delay Medigap Enrollment

If you enroll in Medigap after your six-month window has passed, private insurers may require you to undergo medical underwriting. This means:

• They can reject your application due to health issues

• You may face significantly higher premiums

• Certain pre-existing conditions might not be covered right away

While some states offer additional protections beyond federal rules, most do not. In those cases, missing the OEP in 2025 can create long-term financial challenges.

When You May Get a Second Chance

There are limited situations where you may qualify for guaranteed issue rights even after your OEP ends. These include:

• Losing other supplemental health coverage

• Moving out of your plan’s service area

• Your Medicare Advantage plan leaving the market or ending coverage in your area

These special cases typically give you 63 days from the loss of other coverage to enroll in a Medigap plan with no underwriting.

Why the Timing Can Save You Thousands

Medigap plans tend to have predictable costs and low out-of-pocket expenses when used with Original Medicare. If you wait too long to enroll:

• You may be stuck with high deductibles, copays, or coinsurance

• You might lose access to plans with broader benefits

• You could pay more each month indefinitely due to health-based rating

Buying at the right time allows you to lock in lower rates and enjoy broader access.

How Medigap Enrollment Works in 2025

In 2025, Medigap enrollment follows these federal rules:

• Plans are standardized in most states (A, B, D, G, K, L, M, N)

• Plan C and Plan F are not available to people new to Medicare after January 1, 2020

• Rates are based on your age, location, gender, tobacco use, and sometimes your health

States like New York and Connecticut have year-round open enrollment for Medigap, but that is the exception. In most states, waiting past your one-time window adds unnecessary risk.

Common Misunderstandings About Enrollment Timing

Many people assume they can enroll in a Medigap plan at any time without issue. In reality:

• You can apply anytime, but you may not be accepted

• There is no annual open enrollment for Medigap like there is for Medicare Advantage or Part D

• Pre-existing conditions may cause delays or denials outside of your one-time OEP

This misunderstanding leads some to postpone enrollment, only to find later they have fewer options and higher prices.

Medigap and Medicare Advantage Aren’t Interchangeable

You can’t have both a Medigap policy and a Medicare Advantage plan at the same time. If you choose Medicare Advantage and later want to switch back to Original Medicare with Medigap:

• You may not regain your guaranteed issue rights unless you qualify for a special circumstance

• Your health history will likely affect your eligibility

The trial right allows you to try Medicare Advantage for up to 12 months after first joining at age 65. If you switch back within that window, you may still get Medigap without underwriting. After that, switching carries risks.

Why Some Delay—and Why That Can Backfire

People often delay Medigap enrollment because:

• They feel healthy and don’t anticipate medical expenses

• They mistakenly believe they can join anytime without penalty

• They’re overwhelmed by plan choices and defer the decision

Unfortunately, this delay can backfire:

• A new diagnosis can make coverage unaffordable or inaccessible

• You might only qualify for plans with limited benefits

• Financial unpredictability becomes a long-term issue

Prescription Drug Coverage Isn’t Included

One common surprise is that Medigap doesn’t include drug coverage. You must buy a standalone Part D plan if you want prescription benefits. Delaying Part D can also result in late enrollment penalties, which apply for life.

In 2025, the Part D late enrollment penalty is calculated as 1% of the national base premium for every month you delay coverage after becoming eligible, unless you had creditable drug coverage.

Comparing Plan Types Before It’s Too Late

Not all Medigap plans offer the same coverage. In 2025, Plan G and Plan N remain popular because they provide robust coverage at varying levels of cost-sharing.

When comparing plan types, consider:

• How often you see doctors or specialists

• Your likelihood of needing hospital care

• Whether you travel frequently outside the U.S.

• Your monthly budget and ability to absorb out-of-pocket costs

Choosing a plan during your OEP gives you access to the full range of available options, without restrictions based on your health.

Switching Medigap Plans Later Is Difficult

Even if you’re already enrolled in a Medigap plan, switching later in life is not guaranteed. In most states:

• You must go through medical underwriting to change plans

• Your premium may increase with age and health status

• You might not be approved for a switch at all

If you start with a more limited plan to save on premiums and later want more comprehensive coverage, that switch may not be possible.

Timing Isn’t Just About Eligibility—It’s About Security

At its core, choosing when to buy a Medigap plan is about securing your financial future. You never know when you’ll need more coverage, and once your window closes, the risk becomes personal:

• More out-of-pocket expenses

• Fewer options

• Higher long-term costs

Enrolling during your Medigap Open Enrollment Period is the most reliable way to lock in protection.

Make Smart Timing Work for You

In 2025, Medigap plans continue to play a critical role in managing healthcare costs. But they only work as intended if you understand the timing involved.

Your six-month OEP is a one-time opportunity to gain access to all available plans without underwriting or extra costs. After that, the doors don’t necessarily stay open.

Take control of your Medicare journey now. If you’re nearing 65 or recently enrolled in Part B, talk to a licensed agent listed on this website to explore your Medigap options while timing is on your side.