Medigap vs Medicare Advantage: The Basic Differences, and Why Your First Choice at 65 Matters
Part of our health insurance and Medicare basics guide. Once you have Medicare Part A and Part B, you choose one of two paths: Original Medicare, which you can pair with a Medigap policy, or a Medicare Advantage plan. This page compares the two the way Medicare.gov does, on doctors, costs, coverage and switching rights.
This is educational only. We do not recommend a path, a plan or an insurer, and we do not sell Medicare coverage. For free, unbiased one-on-one help, contact your State Health Insurance Assistance Program (SHIP) at shiphelp.org, or compare plans with Medicare.gov's Plan Finder.
Key takeaways
- Medigap only works with Original Medicare. Medicare.gov says you can only buy Medigap if you have Original Medicare.
- Original Medicare has no yearly out-of-pocket limit on its own. Medicare Advantage plans have one.
- Original Medicare lets you use any provider that takes Medicare in the U.S.; Medicare Advantage plans may require network providers and referrals.
- Your federal right to buy any Medigap policy without health questions is a one-time 6-month window. Later switches back to Medigap can face medical underwriting.
What is the difference between Medigap and Medicare Advantage?
They are different kinds of products. Medicare.gov defines Medigap as "extra insurance you can buy from a private insurance company to help pay your share of out-of-pocket costs in Original Medicare," such as copayments, coinsurance and deductibles. A Medicare Advantage plan (Part C) is a Medicare-approved plan from a private company that you choose instead of Original Medicare to cover most Part A and Part B benefits, and it usually includes drug coverage.
So the real comparison is Original Medicare (often with Medigap and a separate drug plan) against Medicare Advantage.
| Topic | Original Medicare (with or without Medigap) | Medicare Advantage |
|---|---|---|
| Doctors and hospitals | Any doctor or hospital that takes Medicare, anywhere in the U.S. | May need to use the plan's network and service area for non-emergency care |
| Specialist referrals | In most cases not needed | May be needed |
| Your share for Part B services | Usually 20% of the Medicare-approved amount after the deductible; Medigap can help pay it | Out-of-pocket costs vary by plan |
| Yearly out-of-pocket limit | None, unless you have supplemental coverage such as Medigap | Plans have a yearly limit on covered services |
| Premiums | Part B premium, plus Medigap and Part D premiums if you buy them | Part B premium, and may pay the plan's premium; some plans are $0 |
| Drug coverage | Join a separate Medicare drug plan | Most plans include it |
| Prior authorization | In most cases not needed | May be needed for certain services |
| Extra benefits (vision, hearing, dental) | Generally not covered | Plans may offer some |
| Care outside the U.S. | Generally not covered; some Medigap policies cover emergency care abroad | Generally not covered; some plans offer emergency coverage abroad |
Source: Medicare.gov, "Compare Original Medicare & Medicare Advantage," accessed October 1, 2026.
How do Medigap plans work?
Medigap policies are standardized. Policies with the same letter offer the same basic benefits no matter which insurer sells them, and "price is the only difference" between plans with the same letter from different insurers. Most states offer 10 lettered plans: A to D, F, G and K to N. Massachusetts, Minnesota and Wisconsin standardize Medigap differently.
Because the benefits behind each letter are fixed, comparing Medigap policies mostly comes down to the premium and how the insurer prices it over time. Your SHIP or state insurance department can explain how pricing works in your state.
Why does your first choice at 65 matter?
Because the right to buy Medigap without health questions is narrow and mostly front-loaded.
Under federal law you get one Medigap Open Enrollment Period. Medicare.gov says it "starts the first month you have Medicare Part B and you're 65 or older" and lasts 6 months. During it, an insurer "can't refuse to sell you any of the medical policies it offers" or charge more for pre-existing conditions. After it, Medicare.gov says, "the insurance company is allowed to deny you a policy if you don't meet their medical underwriting requirements," unless you have a guaranteed issue right.
That asymmetry shapes the decision:
- Starting with Original Medicare plus Medigap keeps the Medigap option you bought during open enrollment. You can still move to Medicare Advantage later during annual enrollment windows.
- Starting with Medicare Advantage means a later move to Original Medicare is allowed each year, but buying a Medigap policy at that point may involve health questions unless a federal or state protection applies.
Can you switch from Medicare Advantage to Medigap later?
You can leave Medicare Advantage at set times. Medicare.gov lists two: Open Enrollment, October 15 to December 7, when you can "switch from a Medicare Advantage Plan to Original Medicare," and the Medicare Advantage Open Enrollment Period, January 1 to March 31, when people already in a Medicare Advantage plan can "drop your Medicare Advantage Plan and return to Original Medicare."
Getting a Medigap policy at that point is the harder part. The CMS guide "Choosing a Medigap Policy" lists federal guaranteed issue rights, including two trial rights:
- You joined a Medicare Advantage plan when first eligible for Part A at 65 and, within the first year, decide to switch to Original Medicare. You can buy any Medigap policy sold in your state.
- You dropped a Medigap policy to join Medicare Advantage for the first time, have been in the plan less than a year, and want to go back. You can repurchase your old Medigap policy if the same insurer still sells it.
For both, CMS says to apply as early as 60 days before your coverage ends and no later than 63 days after it ends.
State rules can add rights: CMS says, "You may have additional rights under state law," and points readers to their SHIP or state insurance department. Several states give people who already have Medigap an annual window to change policies; see our table of Medigap birthday rule states.
Which questions should you answer before choosing?
We are not recommending either path. These are the questions Medicare.gov's comparison raises, framed so you can take them to a SHIP counselor:
- Your doctors. Do they take Original Medicare, and are they in the networks of plans available in your area?
- Travel. Do you spend time outside a plan's service area or outside the U.S.?
- Cost shape. Would you rather pay a higher fixed premium with lower costs at the point of care, or the reverse with a yearly cap? Medicare.gov notes Original Medicare alone has no yearly cap.
- Drugs. Are your prescriptions covered, under a separate Part D plan or a plan's built-in coverage?
- Prior authorization. How would approval requirements affect care you already get?
- Future flexibility. If you start with Medicare Advantage, would you be able to buy Medigap later in your state?
The timing of all this starts with Part B. See our Medicare enrollment timeline for turning 65 for when your Medigap window opens.
FAQ
Can I have Medigap and Medicare Advantage at the same time? No. Medicare.gov says "You can only buy Medigap if you have Original Medicare."
Are all Medigap Plan G policies the same? In most states, yes for benefits. Medicare.gov says plans with the same letter offer the same basic benefits and price is the only difference. Massachusetts, Minnesota and Wisconsin standardize differently.
When does my Medigap Open Enrollment Period start? The first month you have Part B and are 65 or older, for 6 months, per Medicare.gov. It is one-time and does not repeat each year.
If I join Medicare Advantage at 65 and dislike it, what can I do? CMS lists a trial right: if you joined when first eligible at 65 and switch to Original Medicare within the first year, you have a guaranteed issue right to buy any Medigap policy sold in your state.
Who can help me compare without a sales pitch? Your State Health Insurance Assistance Program offers free local counseling. Find it at shiphelp.org.
Sources
- Medicare.gov, "Compare Original Medicare & Medicare Advantage," accessed October 1, 2026. https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/your-coverage-options/compare-original-medicare-medicare-advantage
- Medicare.gov, "Get Medigap Basics," accessed October 1, 2026. https://www.medicare.gov/health-drug-plans/medigap/basics
- Medicare.gov, "Get ready to buy" (Medigap), accessed October 1, 2026. https://www.medicare.gov/health-drug-plans/medigap/ready-to-buy
- Medicare.gov, "Joining a plan," accessed October 1, 2026. https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan
- Centers for Medicare & Medicaid Services, "Choosing a Medigap Policy" (publication 02110), accessed October 1, 2026. https://www.medicare.gov/publications/02110-choosing-a-medigap-policy.pdf
- SHIP Technical Assistance Center, "Get Medicare Help from Your Local SHIP Program," accessed October 1, 2026. https://www.shiphelp.org/
This page is general information, not insurance, legal or enrollment advice. FinanceRazor does not sell or recommend Medicare plans or insurers. For help with your situation, contact your State Health Insurance Assistance Program or Medicare.gov.