Updated July 2026 · Reviewed by the CoverageCo team
A Medigap policy is private insurance that pays the share Original Medicare leaves you — deductibles, copays, and coinsurance. You keep Original Medicare, add a Medigap policy, and usually add a separate Part D drug plan. There's no network: any provider nationwide who accepts Medicare accepts your coverage.
Key takeaways
- Medigap works alongside Original Medicare, never alongside a Medicare Advantage plan.
- Plans are standardized by letter, so Plan G from one insurer covers the same things as Plan G from another.
- Because benefits are identical by letter, price and the insurer's rate history are what actually differ.
- Your one-time Medigap open enrollment window is the only period you're guaranteed acceptance regardless of health.
What Medigap actually pays for
Original Medicare covers most of your care but leaves you responsible for deductibles, copays, and coinsurance — and it has no annual limit on what those can add up to.
A Medigap policy steps into that gap. Depending on the plan letter you choose, it can cover your Part A hospital coinsurance, your Part B coinsurance, hospice coinsurance, the first three pints of blood, skilled nursing coinsurance, and more.
What it doesn't do is add benefits Medicare never covered. Medigap won't give you routine dental, vision, hearing, or long-term custodial care.
Why the plans are letters
Medigap plans are standardized by federal law and labeled with letters. That standardization is genuinely useful and widely misunderstood.
Plan G from one insurance company covers exactly the same things as Plan G from another. The benefits are identical by law. What differs is the premium, how the company raises rates over time, and the service you get.
That means shopping Medigap is mostly a pricing exercise once you've chosen a letter — which is the opposite of how most people approach it.
| Consideration | What it means |
|---|---|
| Benefits | Fixed by law for each letter — identical across insurers |
| Premium | Varies significantly between insurers for the same letter |
| Rate increases | Vary by company and pricing method — ask about history |
| Network | None — any provider accepting Medicare |
| Drug coverage | Not included; add a separate Part D plan |
The enrollment window that decides everything
This is the most consequential thing on this page.
Your Medigap open enrollment period is a one-time, six-month window that starts when you're 65 or older and enrolled in Part B. During it, you can buy any Medigap policy sold in your state regardless of your health. No medical questions, no denial, no surcharge for pre-existing conditions.
Once it closes, most states allow insurers to medically underwrite you. You can apply, but you can also be declined or charged more based on your health history. A limited set of guaranteed-issue rights exist in specific situations, but they don't cover most circumstances.
If there's any chance you'll want Medigap, this window is the moment it's cheapest and easiest to secure.
Who Medigap tends to suit
Medigap generally fits people who want predictable costs and are willing to pay a higher premium to get them, who travel or live in more than one state, who have doctors or hospital systems they won't change, or who have a condition that means frequent care.
It fits less well for people whose budget makes the monthly premium genuinely difficult, or who place high value on the bundled extras that Advantage plans include.
Common questions
What does Medigap not cover?
Medigap doesn't add benefits Medicare never covered. It generally excludes routine dental, vision, hearing aids, and long-term custodial care, and it doesn't include prescription drug coverage — you'd add a separate Part D plan for that.
Can I have Medigap and Medicare Advantage at the same time?
No. Medigap only works alongside Original Medicare. It's illegal for someone to sell you a Medigap policy while you're enrolled in a Medicare Advantage plan, unless you're leaving Advantage and returning to Original Medicare.
Is Plan G from one company different from Plan G at another?
No. Medigap benefits are standardized by law, so the same letter covers the same things at every insurer. What differs is the premium, the company's history of rate increases, and customer service.
Can I be denied a Medigap policy?
During your six-month Medigap open enrollment period, no — acceptance is guaranteed regardless of health. Outside that window, and outside a limited set of guaranteed-issue situations, most states let insurers review your health and decline you.