Medicare Supplement Plans Cover the Gaps Medicare Leaves Behind

A Medicare Supplement plan (also called Medigap) pays for costs that Original Medicare does not — mainly your share of doctor and hospital bills. Medicare itself covers a lot, but it leaves you responsible for deductibles, copayments, and coinsurance. A Medigap plan picks up some or all of those costs, depending on which plan you choose.

The key thing to understand is that Medigap plans work only with Original Medicare (Parts A and B). They do not work with Medicare Advantage plans. If you have Advantage, you cannot buy a Medigap plan at the same time.

Key Takeaways

  • Medicare Supplement plans cover the deductibles, copayments, and coinsurance that Original Medicare does not pay.
  • There are ten standardized Medigap plans (A, B, D, G, K, L, M, N, and two versions of Plan C), and each covers a different combination of costs.
  • Plan G covers the most expenses for most people, but Plan N costs less per month and may save you money if you do not go to the doctor often.
  • Medigap plans do not cover dental, vision, hearing aids, or long-term care — you need separate coverage or pay out of pocket for those.
  • You can switch plans during your open enrollment period (the month you turn 65 and the three months after), though switching later may cost more or require health questions.

The Ten Standardized Plans and What Each Covers

Insurance companies must offer Medigap plans in one of ten standardized designs set by federal law. Every Plan G from every company covers the same things — the company can only charge different prices, not change what is covered. This makes it easier to compare plans side by side.

The most common plans are G, N, and D. Plan G covers your Part B deductible, coinsurance for hospital and doctor visits, and blood transfusions. Plan N is cheaper but requires you to pay a copayment at the doctor's office (usually $20) and at urgent care (usually $50). Plan D is the least expensive but covers fewer costs. Plans A, B, K, and L exist but are chosen less often. Plans M and the two versions of Plan C are being phased out — insurance companies can no longer sell them to people newly turning 65, though people who already have them can keep them.

The exact costs you pay depend on which plan you choose and which insurance company sells it to you. A Plan G from one company might cost $150 a month while the same plan from another costs $180. Comparing prices from at least three companies is worth doing, because the difference adds up over a year.

What Medigap Does Not Cover

Medigap plans have clear limits. They do not cover dental work, eye exams, glasses, or hearing aids. They do not cover long-term care (nursing home or in-home care). They do not cover prescription drugs — you need a separate Part D plan for that. They do not cover medical equipment like wheelchairs or oxygen unless Medicare itself covers it first.

If you need dental or vision care, you can buy a separate plan from a private company, or you can pay out of pocket. Some seniors choose to set aside money each month for these costs instead of buying extra coverage. Others use discount dental plans, which are not insurance but offer reduced rates at participating dentists.

How Medigap Works When You See a Doctor

When you go to the doctor, you show your Medicare card and your Medigap card. The doctor's office bills Medicare first. Medicare pays its share and sends you a bill for what it does not cover — your deductible, copayment, or coinsurance. Then your Medigap plan pays that bill (or most of it, depending on your plan). In most cases, you pay nothing out of pocket.

This is different from Medicare Advantage, where you show one card and the insurance company handles everything. With Medigap and Original Medicare, the process takes a few extra weeks because two companies are involved, but the end result is usually lower out-of-pocket costs.

When You Can Buy or Switch a Medigap Plan

The best time to buy a Medigap plan is during your open enrollment period, which runs for six months starting the month you turn 65 and enroll in Medicare Part B. During this window, insurance companies cannot turn you down or charge you more because of health problems you have. This is called may provide issue.

If you miss this window, you can still buy a Medigap plan, but the company can ask health questions and may refuse to cover certain conditions for a waiting period. Some states have additional protections that extend may provide issue, but not all do. Once you have a Medigap plan, you can switch to a different plan at any time, but switching outside your open enrollment period may trigger health questions again.

If you are already on Medicare Advantage and want to switch to Original Medicare with a Medigap plan, you have a one-time window to do so without health questions. This window is 12 months from when you first enrolled in Advantage. After that, switching may require health approval.

How Much Medigap Plans Cost

Medigap premiums vary widely by plan, location, age, and insurance company. A Plan G might cost $120 to $250 per month depending on where you live and who sells it. Plan N might cost $80 to $150. These are rough ranges — your actual price depends on your zip code and the company you choose.

Insurance companies use three different pricing methods: community-rated (everyone in your area pays the same), age-rated (your age affects the price), and issue-age-rated (the price is based on your age when you bought the plan and does not go up as you age). Issue-age-rated plans are often cheaper when you first buy them but may be more expensive overall if you keep them for many years. Ask the company which method they use before you buy.

Frequently Asked Questions

Can I have both a Medigap plan and a Medicare Advantage plan?

No. You can have either Original Medicare with a Medigap plan, or Medicare Advantage. If you have Advantage and buy a Medigap plan, the Medigap plan will not pay anything because Advantage already covers those costs. You would be paying for coverage you cannot use.

Does Medigap cover prescription drugs?

No. You need a separate Part D prescription drug plan. You can buy Part D from any insurance company during your initial enrollment period or during the annual open enrollment period in the fall. If you do not buy Part D when you first become may be able to access, you may pay a penalty later.

What happens to my Medigap plan if I move to a different state?

Your current plan may not be available in your new state, because each state regulates Medigap differently. You can switch to a different Medigap plan in your new state, and if you move within 12 months of first buying your original plan, you may have may provide issue protections. Contact your current insurance company at least 30 days before you move to ask about your options.

Is Plan G always better than Plan N because it costs less out of pocket?

Not necessarily. Plan G has a higher monthly premium but lower costs when you see a doctor. Plan N has a lower monthly premium but you pay copayments at visits. If you see the doctor rarely, Plan N may cost you less overall. If you see the doctor often, Plan G usually saves you money. Do the math for your own situation before you choose.

Can I switch Medigap plans if my health gets worse?

You can switch plans at any time, but if you switch outside your open enrollment period, the new company can ask health questions and may refuse to cover your new condition. Some states have rules that protect you in certain situations — for example, if your current company stops selling your plan in your area. Check with your state's insurance commissioner's office to see what protections explore where you live.