Quick answer: Medigap is private insurance that helps pay the deductibles, copays, and coinsurance that Original Medicare leaves behind. There are 10 standardized plans (A through N in most states), and you’re only guaranteed acceptance during a 6-month window that starts when you’re 65 and enrolled in Part B.
What Medigap Does
Original Medicare doesn’t cover 100% of your costs — you’re responsible for deductibles, coinsurance, and copays. Medigap policies, sold by private insurers, are designed to cover some or all of that gap, working alongside Original Medicare (not Medicare Advantage).
The Plans, Compared
Plans are labeled by letter, and every insurer selling the same letter must offer identical basic benefits in most states. Plans C and F are closed to anyone newly eligible for Medicare on or after January 1, 2020 — Plans D and G are their modern equivalents. See the full plan-by-plan comparison.
When You’re Guaranteed Acceptance
Your Medigap Open Enrollment Period is a 6-month window starting the month you’re 65 and enrolled in Part B. During this window, insurers can’t deny you or charge more based on your health. See exactly when your window opens and closes.
A Few Rules Worth Knowing
- You need Medicare Part A and Part B to buy a Medigap policy.
- Medigap only covers one person — spouses need separate policies.
- You can’t use Medigap alongside Medicare Advantage.
- Today’s Medigap policies don’t cover prescription drugs — that’s what Part D is for.
Frequently Asked Questions
Do I have to buy Medigap?
No, it’s optional. Without it, you’re responsible for all of Original Medicare’s deductibles and coinsurance yourself.
Which Medigap plan is best?
It depends on your health needs, budget, and how much risk you’re comfortable carrying yourself. See our guide to choosing the best Medigap plan for your needs.
Can I switch Medigap plans later?
Yes, but outside your initial 6-month open enrollment window, insurers can use medical underwriting unless you qualify for a guaranteed issue right.
