To apply for Medicare Supplement insurance: enroll in Medicare Part A and Part B, choose a Medigap plan letter, and submit your application to a private insurance company — ideally during your six-month Medigap Open Enrollment Period to avoid medical underwriting.
In more detail: applying generally involves confirming your Medicare Part A and Part B enrollment, choosing a Medigap plan letter, comparing insurance companies and premiums, determining whether medical underwriting applies, submitting an application with your Medicare card information on hand, and confirming the new policy's effective date before canceling any existing coverage.
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In This Guide
At a Glance
This is the short version. For what to have ready, underwriting rules, and what happens after you apply, see the full walkthrough below.
Before You Start
Having this on hand before you start makes the application faster, whether you apply yourself or have an agent submit it for you.
The Application Process
You generally need to be enrolled in both Medicare Part A and Part B before you can apply for a Medigap policy. You can confirm your enrollment and effective dates through your Medicare account at Medicare.gov or on your red, white, and blue Medicare card.
Your six-month Medigap Open Enrollment Period starts the month you're 65 or older and enrolled in Part B. During this window, insurers generally cannot use medical underwriting to deny you a policy or charge you more. Applying outside this window — or outside a guaranteed issue situation — usually means underwriting can apply. See our full breakdown of Medigap Open Enrollment timing and rules before you apply.
Most applicants choose between Plan G, which offers broader coverage, and Plan N, which can carry a lower premium in exchange for a few small copays. Plan benefits are standardized by letter in most states, so this decision is about coverage level and budget, not which company you'll eventually buy from.
Once you know your plan letter, the benefits are the same no matter which company sells it — but premiums, discounts, and rate history are not. It's worth comparing a few companies for the same plan letter rather than applying with the first one you find. See how identical coverage can carry different prices from company to company.
This step matters more than any other in determining how smoothly your application goes. If you're applying during a protected window — your Open Enrollment Period or a guaranteed issue situation — the insurer generally cannot ask health questions or use your medical history to deny coverage. Outside those windows, the carrier may require you to answer health questions as part of underwriting, and your application could be approved, modified, or declined based on the results.
Applications typically ask for your personal and Medicare information, your preferred effective date, payment authorization, and — if underwriting applies — a set of health questions. You can usually apply directly with the carrier online, by phone, or on paper, or have a licensed agent prepare and submit it for you after reviewing your options.
After You Apply
How long each stage takes depends on the carrier, your state, and whether underwriting is involved — see the timing section below. Keep any existing coverage active until you have a confirmed effective date in hand.
Very Important If You're Switching
If you already have a Medigap policy and you're applying for a different one — often after a premium increase — the order of operations matters. Applying for the new policy is only the first step.
Submit your application with the new company while your current policy stays active.
Don't assume approval. Wait for written confirmation from the new carrier.
Get the exact start date of the new policy in writing before you do anything else.
Cancel your existing coverage after the new policy's effective date is confirmed — never before.
Canceling your current policy before the replacement is approved and active can leave you with a gap in coverage, or with no Medigap policy at all if the new application is declined. This sequence matters most when underwriting could apply to your new application. If your current rate increase is what's driving the switch, see our full explanation of why Medicare Supplement rates increase and our 2026 rate increase report for current examples by carrier and state.
Underwriting
Yes — but only in certain situations. Whether your application can be declined comes down to timing.
During your Medigap Open Enrollment Period or a guaranteed issue situation, an insurer generally cannot decline your application or charge you more based on your health history.
If medical underwriting applies, the insurer can review your health history and may approve, decline, or modify the terms of your application based on their underwriting rules.
If you're not sure which situation applies to you, that's worth confirming before you apply rather than after — it can change how you approach the whole process.
Timing
There's no single fixed timeline — processing time varies by carrier, by state, and by whether medical underwriting is involved. Applications submitted during a protected enrollment window, with no health questions to review, often move faster than applications requiring full underwriting. Some carriers can turn around a straightforward application within days; others, particularly ones requiring additional medical information, can take longer.
If timing matters to you — for example, you need to avoid a coverage gap while switching companies — it's worth asking the carrier or your agent for a realistic estimate for your specific situation rather than assuming a standard number of days.
Not Sure Where to Start?
From confirming your enrollment timing to comparing companies and checking whether underwriting applies, a licensed agent can prepare your application so nothing gets missed.
No cost to you. No obligation to enroll.
Application Questions
A licensed Lehigh Partners Senior Benefits agent can confirm your enrollment timing, compare companies for your chosen plan letter, check whether underwriting applies, and prepare your application from start to finish.
No cost to you. No obligation to enroll.
You pay the exact same premium whether you apply directly with a carrier or use our services.
Disclosure
Lehigh Partners Senior Benefits is a licensed insurance agency and is not connected with or endorsed by the United States government or the federal Medicare program. We do not offer every plan available in your area. We represent selected insurance organizations and products in the areas we serve. Contact Medicare.gov or 1-800-MEDICARE for information about all available options. Plan availability, premiums, underwriting requirements, guaranteed-issue rights, application processing times, and state protections vary by carrier and state. This page provides general educational information and is not a substitute for advice based on your individual circumstances.
