Open enrollment for Medicare is in a couple of days, and it’s normal to have questions.
If you’ve started exploring Medicare options, you’ve probably noticed the maze of letters — Part A, Part B, Part D, and something called Medigap. It’s enough to make anyone’s head spin.
But understanding how Medicare and Medigap work (and how they don’t overlap) can save you from big out-of-pocket surprises later. Let’s break it down simply.
What Is Medicare?
Think of Medicare as the foundation of your health coverage after age 65.
It’s a federal program, and it comes in parts:
- Part A – Covers hospital stays and skilled nursing care.
- Part B – Covers doctor visits, preventive care, and outpatient services.
- Part D – Helps pay for prescription drugs (if you add it).
- Part C (Medicare Advantage) – Combines A and B (and often D) into a single private plan, sometimes with extra perks like dental or vision.
If you’re on what’s called Original Medicare, that means you have Part A and Part B directly through the government. It’s great coverage — but it’s not complete coverage.
Original Medicare doesn’t include an annual out-of-pocket cap, so you’re responsible for 20% of most medical costs after deductibles. That’s where Medigap steps in.
What Is Medigap?
Medigap (also called Medicare Supplement Insurance) is private insurance you can buy to fill the “gaps” in Original Medicare.
It helps pay for things Medicare doesn’t fully cover — like copayments, coinsurance, and deductibles. There are multiple Medigap plans, labeled by letters (Plan A, Plan G, etc.), and they’re standardized. That means a Plan G from one insurer has the same benefits as a Plan G from another — only the price differs.
Here’s the key: you can only have Medigap if you have Original Medicare (A and B) — not if you’re enrolled in Medicare Advantage.
Feature | Medicare (Original) | Medigap (Supplement) |
Purpose | Core federal health coverage (Parts A & B) | Fills “gaps” in Original Medicare (out-of-pocket costs) |
Who Provides It | Federal government | Private insurance companies |
What It Covers | Hospital, doctor, and medical services | Deductibles, coinsurance, copayments |
Prescription Drugs | Not included (add Part D separately) | Not included (requires separate Part D plan) |
Provider Flexibility | Any doctor or hospital that accepts Medicare | Same flexibility (no network limits) |
Out-of-Pocket Maximum | None — you pay 20% of most services | Most or all costs covered depending on plan |
Standardization | Coverage defined by law (Parts A–D) | Plans standardized by letters (A–N) |
Enrollment Timing | When you turn 65 or become eligible | Best during 6-month Medigap Open Enrollment after enrolling in Part B |
The Bottom Line
- Medicare is your main coverage through the federal government.
- Medigap is supplemental insurance that helps pay the costs Medicare doesn’t.
- You can’t have both Medigap and Medicare Advantage at the same time.
Both can be valuable — the key is knowing which fits your needs best.
We’re Here to Help
Medicare decisions can be confusing, but you don’t have to navigate them alone.
Evergreen Wealth Advisors has a dedicated Medicare Division that specializes in helping you compare plans, understand your options, and make confident decisions about your healthcare coverage.