Original Medicare covers a lot, but not everything—and the gaps can get expensive fast. Supplemental insurance, commonly called Medigap, fills those holes by covering costs like copayments, coinsurance, and deductibles that Original Medicare leaves on your shoulders. If you're trying to avoid surprise medical bills in retirement, understanding your Medigap options is essential.
How Medigap Works
Medigap policies are sold by private insurance companies and work alongside Original Medicare (Parts A and B). When you receive care, Medicare pays its share first, then your Medigap plan covers eligible out-of-pocket costs up to the plan's limits. You'll still pay your monthly Medigap premium on top of your Medicare Part B premium, but you gain predictability—you know roughly what your healthcare costs will be each year.
The catch: Medigap doesn't cover everything. These plans don't pay for long-term care, dental, vision, hearing aids, or prescriptions (that's what Part D is for). They also won't cover costs tied to Medicare Advantage plans, which operate under different rules entirely.
The 10 Standardized Plans
The good news is that the alphabet soup of plans follows a federal standard. There are currently 10 plans labeled A through N, and each offers the same benefits regardless of which insurer sells it. This means Plan F from one company covers identical items as Plan F from another—the only real difference is price.
Here's what you need to know about the most popular options:
- Plan F: The most comprehensive but also the most expensive. It covers everything except your Part B deductible. If you enrolled in Medicare before 2020, this is still available to you; newer enrollees cannot purchase it.
- Plan G: The modern equivalent to Plan F for those turning 65 after 2019. Covers nearly everything except the Part B deductible (which was $240 in 2024). Monthly premiums typically run $120–$250 depending on your age and location.
- Plan N: A less expensive alternative that requires small copays ($20 for doctor visits, $50 for ER) but leaves you responsible for the Part B excess charge (when a doctor charges more than Medicare approves). Premiums average $80–$160 monthly.
- Plan A: A basic, budget-friendly option with the lowest premiums ($50–$120 monthly) but more out-of-pocket costs. Best for those with minimal healthcare needs.
Enrollment Timing Matters
Your best window to buy Medigap is within six months of enrolling in Medicare Part B. During this "Open Enrollment Period," insurers cannot deny you or charge more based on pre-existing conditions—this is called guaranteed issue. Miss this window, and you may face medical underwriting, higher premiums, or outright rejection if you have significant health issues.
If you're currently on Medicare Advantage and thinking of switching to Original Medicare plus Medigap, you have a 63-day window after leaving Medicare Advantage to purchase a Medigap plan without facing underwriting delays or exclusions.
Cost Ranges and What to Budget
Medigap premiums vary significantly by state, age, and insurer. A 65-year-old in a rural area might pay $100–$180 monthly for Plan G, while a 75-year-old in an urban area could pay $250–$400. Income-based Medicare savings programs exist if you qualify, but they typically aren't advertised prominently—ask your local Social Security office.
Beyond premiums, remember you'll still owe:
- Your Part B premium (~$175/month in 2024)
- Part A deductible (~$1,632 in 2024, though some plans cover this)
- Copays or coinsurance for Part D drugs, if applicable
How to Compare and Choose
Start by identifying which plans are available in your zip code—not all 10 are offered everywhere. Then compare quotes from at least three insurers; rates can differ by $50+ monthly for the same plan. Many insurers offer discounts for automatic payments or bundling with other policies.
Use official Medicare resources (Medicare.gov) or work with a licensed insurance agent. Mercoly helps you compare and find trusted health insurance providers in one place, making it easier to weigh your actual options side-by-side.
Frequently Asked Questions
Q: Can I switch Medigap plans after I've enrolled? Yes, you can switch anytime, but outside your Open Enrollment Period you may face underwriting or waiting periods, so compare carefully before making the move.
Q: Do Medigap plans cover prescription drugs? No—you need a separate Part D plan to cover prescriptions, and it works independently of your Medigap coverage.
Q: What's the difference between Medigap and Medicare Advantage? Medigap supplements Original Medicare, while Medicare Advantage replaces it with a different network-based plan structure, typically including drug coverage but with stricter provider networks.
Compare Medigap quotes today to lock in the best rate for your situation.