The Short Answer (and Why It Matters)
Original Medicare doesn’t pay for everything. Not even close. If you get sick or need surgery, you could be on the hook for thousands of dollars in out-of-pocket costs. Medigap insurance exists to fill those gaps — and that’s literally where the name comes from.
Medigap (also called Medicare Supplement Insurance) is a private health insurance policy you buy to cover costs that Medicare Parts A and B leave behind. Things like deductibles, copayments, and coinsurance. Without it, you’re exposed to real financial risk every time you use your Medicare coverage.
Here’s the thing most people don’t realize: Original Medicare covers about 80% of your approved medical costs after you meet your deductible. That remaining 20%? There’s no cap on it. If you have a $500,000 hospital stay, you could owe $100,000 out of pocket. Medigap puts a ceiling on that exposure.
How Medigap Actually Works Day-to-Day
Think of it as a tag-team system. Medicare pays its share first. Then your Medigap policy steps in and covers some or all of what’s left. You typically don’t have to file claims yourself — the two insurers coordinate directly behind the scenes.
To have Medigap coverage, you need to already be enrolled in Medicare Part A and Part B. You pay your regular Part B premium to Medicare (which is $174.70 per month in 2024 for most people), and then you pay a separate monthly premium to your private Medigap insurer on top of that.
One policy, one person. Medigap plans are individual — they don’t cover your spouse. If you’re both on Medicare and want this kind of coverage, you’d each buy your own policy.
It’s also worth knowing what Medigap doesn’t cover. It won’t cover prescription drugs (that’s what Part D is for), dental, vision, hearing, or long-term care. It’s strictly about the medical costs tied to your Part A and Part B benefits.
The Different Medigap Plans Explained
There are 10 standardized Medigap plans available in most states, labeled with letters: A, B, C, D, F, G, K, L, M, and N. This is where people’s eyes usually glaze over, so let’s keep it practical.
The federal government standardizes what each plan covers. That means a Plan G from Blue Cross is identical in benefits to a Plan G from Aetna. The only difference is the price and the customer service. This makes comparison shopping much easier once you know which plan you want.
The most popular plans right now are Plan G and Plan N. Here’s why:
- Plan F used to be the gold standard — it covered everything, including the Part B deductible. But it’s no longer available to people who became eligible for Medicare on or after January 1, 2020. If you were eligible before that date, you can still get it.
- Plan G is now the most popular option. It covers almost everything Plan F covered, except the Part B deductible ($240 in 2024). After you pay that deductible once per year, Plan G covers 100% of the rest of your Medicare-approved costs.
- Plan N is a lower-premium option. It covers most costs but requires small copays — up to $20 for doctor visits and up to $50 for emergency room visits. It also doesn’t cover “excess charges” (more on that shortly).
| What’s Covered | Plan A | Plan G | Plan N |
|---|---|---|---|
| Part A coinsurance and hospital costs | Yes | Yes | Yes |
| Part B coinsurance or copayments | Yes | Yes | Yes (with copays) |
| Part A deductible ($1,632 in 2024) | No | Yes | Yes |
| Part B deductible ($240 in 2024) | No | No | No |
| Part B excess charges | No | Yes | No |
| Skilled nursing facility coinsurance | No | Yes | Yes |
| Foreign travel emergency (80%) | No | Yes | Yes |
A quick word on “excess charges.” Some doctors don’t accept Medicare assignment, meaning they can charge up to 15% more than the Medicare-approved amount. If you have Plan N and see one of these doctors, you’d owe that extra amount. Plan G covers it. This isn’t common, but it’s something to know if you travel frequently or live in a state with a lot of non-participating providers.
What Does Medigap Actually Cost?
This is the question everyone wants answered, and the honest answer is: it varies quite a bit. Premiums depend on your age, gender, where you live, which plan you choose, and which insurance company you go with.
That said, here are realistic ballpark figures for 2024-2025 so you have something to work with:
| Plan Type | Age 65 (avg. monthly premium) | Age 70 (avg. monthly premium) |
|---|---|---|
| Plan G | $100 – $200 | $130 – $250 |
| Plan N | $70 – $150 | $90 – $180 |
| Plan F (if eligible) | $130 – $230 | $160 – $280 |
Premiums are consistently lower in some states (like Wisconsin, which has its own standardized system) and higher in places like New York or Florida. Smoking status can also raise your premium significantly — sometimes 10-20% higher.
Insurance companies price their plans in one of three ways: community-rated (everyone pays the same price regardless of age), issue-age-rated (based on how old you are when you buy), and attained-age-rated (goes up as you get older). Attained-age plans often look cheapest at 65 but become the most expensive over time. Ask any insurer how they price their plans before you sign up.
One more thing: premiums aren’t fixed forever. Even if you have a community-rated or issue-age plan, insurers can raise premiums over time due to medical cost inflation. It happens to everyone, but the increases tend to be more predictable with non-attained-age plans.
When to Buy (This Part Is Really Important)
Timing matters enormously with Medigap. There’s a six-month window that starts the month you turn 65 and enroll in Part B. During this window, insurers have to sell you any Medigap plan they offer at standard rates. No health questions. No denial. No higher premium because of pre-existing conditions.
Once that window closes, you can still try to buy Medigap, but insurers in most states can charge you more, deny you coverage, or exclude pre-existing conditions based on your health history. This is not a hypothetical risk — plenty of people in their late 60s who skipped Medigap at 65 find it very hard to get affordable coverage later if their health has changed.
There are some exceptions. If you lose employer-sponsored coverage, for example, you may get a guaranteed issue right. But these situations are specific and limited. The safest move is to buy during your open enrollment window.
What if you’re already past 65 and healthy? You can still apply, and insurers will typically accept healthy applicants. You just won’t have the guaranteed right to coverage. Get your applications in before any health issues arise.
Medigap vs. Medicare Advantage: A Common Confusion
A lot of people mix these two up, or assume they’re the same kind of thing. They’re not.
Medicare Advantage (Part C) replaces Original Medicare entirely. You get your coverage through a private insurer who takes over from Medicare. These plans often include dental, vision, and drug coverage bundled together, and many have $0 premiums. That sounds great on the surface.
Medigap supplements Original Medicare. You keep Medicare as your primary insurance and add the Medigap policy on top. You also need a separate Part D plan for drugs.
The key tradeoff: Medicare Advantage plans usually have networks. You may need referrals, and your coverage may not travel well if you’re out of your plan’s area. Medigap with Original Medicare gives you access to any doctor or hospital in the country that accepts Medicare — and that’s most of them. For retirees who travel, split time between states, or just want total freedom in choosing doctors, that flexibility has real value.
You also can’t have both at the same time. If you’re on Medicare Advantage, you can’t use a Medigap policy — it’s one or the other.
Bottom Line
For most people turning 65 who want predictable healthcare costs and the freedom to see any Medicare-accepting doctor, Plan G is the sweet spot — it covers nearly everything except that $240 Part B deductible, and premiums are reasonable compared to the financial risk you’re offsetting. Buy during your open enrollment window, shop at least 3-4 insurers in your state to compare prices for the same plan, and ask each one how they price their premiums over time.
If you’re on a tighter budget and generally healthy, Plan N is worth a serious look. Just make sure your regular doctors accept Medicare assignment so you won’t get hit with excess charges.
Frequently Asked Questions
Can I be denied Medigap coverage?
Yes, outside of your open enrollment window, private insurers can deny you coverage or charge higher premiums based on your health history in most states. New York and a few other states have year-round guaranteed issue rules, but those are exceptions. This is the biggest reason not to wait.
Does Medigap cover prescription drugs?
No. Medigap policies sold after 2006 don’t include prescription drug coverage. You’ll need to enroll in a standalone Medicare Part D plan for that. You can sign up for Part D during your initial enrollment period or during the annual open enrollment period each fall.
Can I switch Medigap plans later if I want to change?
You can try to switch at any time, but outside of your open enrollment period you’ll likely need to go through medical underwriting. If you’re in good health, many people do successfully switch to save money on premiums. Just don’t cancel your current plan until a new one is confirmed and active.
If I have retiree insurance from my employer, do I still need Medigap?
Not necessarily. Some retiree health plans through employers function similarly to Medigap and may already fill Medicare’s gaps. Review your plan documents carefully and compare what it covers to what a Medigap plan would offer. In some cases, the employer plan is better — in others, switching to Medigap makes more financial sense. A licensed Medicare broker can help you compare.
