Key Takeaways
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While all standardized Medicare Supplement plans (also known as Medigap) must offer the same core benefits within each plan letter, the differences between insurance companies—including costs, rate increases, and underwriting—can significantly affect your coverage experience.
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Timing your enrollment is crucial. Missing your Medigap Open Enrollment Period may mean higher costs, fewer plan choices, or denial due to pre-existing conditions.
Why Medicare Supplement Plans Exist
Original Medicare (Parts A and B) covers many healthcare costs, but not all. You’re responsible for deductibles, copayments, and coinsurance. In 2025, the Medicare Part A hospital deductible is $1,676 per benefit period, and the Part B annual deductible is $257. Without supplemental coverage, these costs can quickly add up.
Medicare Supplement (Medigap) plans are designed to fill these gaps. They are standardized by the federal government, but the companies that sell them are private. And while the core benefits are the same across carriers, how those benefits are delivered—and at what cost—can differ significantly.
Understanding Plan Standardization—But Not Uniformity
Each Medigap plan is identified by a letter, such as Plan G, Plan N, or Plan A. These letters represent a standard set of benefits defined by federal law. For example:
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Plan G covers everything except the Part B deductible.
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Plan N covers most things but may include small copayments for certain visits.
However, standardization ends at the benefits. Everything else—monthly premiums, customer service, rate increase patterns, and application policies—can differ based on the company and your location.
What Varies Between Companies (That You May Not Expect)
Even though Plan G is Plan G everywhere, these aspects can differ widely:
Monthly Premiums
Companies charge different amounts for the same coverage. In 2025, premiums can vary by over a hundred dollars a month for the same plan letter depending on the insurer, your location, age, and health status.
Pricing Methods
How a company sets its rates can make a difference in future costs:
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Community-rated: Everyone pays the same regardless of age.
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Issue-age-rated: Your rate is based on your age when you buy the plan and won’t increase due to aging.
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Attained-age-rated: Your premium increases as you get older.
This affects not just your initial rate but how much you might pay five or ten years later.
Underwriting Rules
Outside of specific enrollment windows, many companies require you to pass medical underwriting. That means if you have health conditions, you could be denied or charged more—unless you’re in a protected window like your one-time Medigap Open Enrollment Period.
Rate Increase History
Some insurers have a reputation for large annual rate hikes, while others remain relatively stable. A plan that seems affordable now could become unsustainable later if the company has a history of sharp increases.
Customer Service and Claims Handling
While every Medigap plan must follow Medicare’s standards, some companies are faster, clearer, and easier to deal with when handling billing issues or policy changes. This becomes important when you’re managing your care.
The Critical Timing of Enrollment
Your Medigap Open Enrollment Period is a one-time window that starts when you’re both 65 or older and enrolled in Medicare Part B. It lasts 6 months. During this period:
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You cannot be denied coverage.
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You pay the same rate as a healthy person.
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You can choose any plan available in your area.
If you miss this window, you may be subject to medical underwriting, especially in most states that don’t have guaranteed issue rights beyond this period.
Switching Plans Isn’t Always Easy
Unlike Medicare Advantage, Medigap doesn’t offer an annual open enrollment window. If you’re already enrolled in a Medigap plan and want to switch, you’ll usually need to answer health questions and risk being denied unless your state has special protections.
Some states like New York and Connecticut offer continuous guaranteed issue rights, but most do not. This makes choosing carefully the first time incredibly important.
When You May Qualify for a Special Enrollment Right
There are a few situations where you may be eligible for guaranteed issue outside your initial Medigap Open Enrollment Period, such as:
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Your Medicare Advantage plan leaves your service area or is terminated.
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You lose other health coverage through no fault of your own.
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You joined a Medicare Advantage plan for the first time and want to return to Original Medicare within 12 months.
Even in these cases, your plan choices may be limited to certain Medigap policies.
Common Missteps That Lead to Coverage Gaps or Higher Costs
Many people make decisions based on incomplete information, which can have lasting financial consequences. Here are some of the most frequent mistakes:
Assuming All Plan Gs Are Equal
They’re equal in benefits, but not in cost, rate stability, or service. A cheaper premium today doesn’t guarantee lower lifetime costs.
Ignoring Pricing Method
Choosing an attained-age-rated plan may seem cheaper at 65, but it could become far more expensive by age 75 or 80.
Waiting Too Long to Enroll
Delaying enrollment after you’re eligible can lead to higher premiums or denial. Your six-month Medigap Open Enrollment Period is the best time to apply.
Switching Without Understanding the Rules
If you try to change Medigap plans outside a guaranteed issue window, you may be subject to underwriting and could be denied.
Confusing Medicare Advantage With Medigap
These are not the same. You cannot use a Medigap plan if you’re enrolled in Medicare Advantage. And if you leave Medicare Advantage to go back to Original Medicare, you may not have the same rights to buy Medigap.
How Medigap Works With Medicare
When you have both Original Medicare and a Medigap policy:
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Medicare pays its share of the approved amount.
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Your Medigap plan pays its share (depending on the benefits of the letter plan you chose).
This helps limit your out-of-pocket costs and simplifies billing. You can see any doctor or specialist that accepts Medicare, with no network restrictions.
Medigap Does Not Include Drug Coverage
Medigap plans do not include prescription drug coverage. If you need medication coverage, you must enroll in a standalone Medicare Part D plan. Without Part D, you could face penalties if you enroll later.
Make sure your drug plan coordinates with your healthcare providers and pharmacy preferences.
Comparing Medigap vs. Medicare Advantage
Choosing between Medigap and Medicare Advantage requires understanding your health needs, budget, and coverage preferences.
Medigap + Original Medicare may be better for you if:
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You want nationwide provider access.
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You see specialists frequently.
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You prefer predictable costs with fewer out-of-pocket surprises.
Medicare Advantage may appeal if:
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You’re comfortable using a provider network.
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You want an all-in-one plan with extra benefits like dental or vision.
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You’re healthy and prefer lower upfront costs.
But once you choose a direction, switching later may come with restrictions.
Why You Should Compare Annually—Even if You Already Have a Plan
Even though Medigap benefits are standardized, premiums change yearly. Companies can raise rates based on age, inflation, or claims data. Reviewing your plan annually helps you:
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Monitor for premium increases.
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Evaluate whether your plan is still a good value.
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Explore options if you’ve moved to a new ZIP code.
Although switching is not always easy, it may be worth exploring if your premiums become unaffordable.
Getting Reliable Help Before You Commit
Medigap is a long-term decision. Once you enroll, switching plans or changing coverage may become difficult. Getting help from someone who understands the current rules, underwriting policies, and cost trends can help you avoid future regrets.
Understanding the Fine Print Can Help You Make the Right Choice
Medicare Supplement plans can offer peace of mind, but only if you choose the right one, at the right time, and for the right reasons. Don’t assume all Plan Gs or Plan Ns are equal—because they’re not. Use your Medigap Open Enrollment Period wisely and evaluate each option beyond just the premium.
For personal guidance based on your health and situation, speak with a licensed agent listed on this website who can help you make a confident, well-informed decision.
