Medicare Supplement Plans Fill the Gaps That Original Medicare Leaves

Medicare Supplement insurance (also called Medigap) pays some of the costs that Original Medicare does not cover — copayments, coinsurance, and deductibles. It does not replace Medicare. You keep your Original Medicare coverage and add a Medigap plan on top of it. When you go to the doctor, Medicare pays its share first, then your Medigap plan pays its share of what Medicare did not cover.

Medigap plans are sold by private insurance companies, not by Medicare itself. The federal government sets what each plan type must cover, so a Plan G from one company covers the same things as a Plan G from another company — the only difference is price. You choose which company to buy from and which plan letter (A, B, D, G, K, L, M, or N) fits your budget and health needs.

Medigap is different from Medicare Advantage (Part C), which is a different way to get Medicare coverage altogether. With Medigap, you use any doctor or hospital that takes Medicare. With Medicare Advantage, you usually have a network and need referrals, like an HMO or PPO.

Key Takeaways

  • Medigap plans are sold by private companies but follow federal rules about what they must cover, so the same plan letter costs the same benefits no matter which company sells it.
  • You keep Original Medicare when you buy Medigap and use any doctor or hospital that accepts Medicare — you are not locked into a network.
  • Different plan letters (A through N) cover different amounts of copayments and deductibles, and Plan G covers the most gaps for people newly turning 65.
  • You can switch Medigap plans during certain windows, but outside those windows an insurance company can deny you or charge more based on your health history.
  • Medigap does not cover dental, vision, hearing aids, or long-term care — you may need separate coverage or to pay out of pocket for those.

What Each Medigap Plan Letter Covers

The federal government defines eight standard Medigap plans (Plan A, B, D, G, K, L, M, and N). Each plan covers a different combination of the costs that Original Medicare leaves behind. Plan G is the most common choice for people turning 65 now because it covers the Part B deductible, which Plan F used to cover but is no longer sold to new enrollees.

Plan A is the most basic and least expensive. It covers coinsurance for hospital stays and some doctor visits, but not the Part B deductible. Plan N is cheaper than Plan G but requires you to pay a copayment at the doctor's office and a higher copayment at urgent care. Plans K and L cover a smaller percentage of costs and have an out-of-pocket limit — once you spend that amount, the plan covers 100 percent of the rest.

No Medigap plan covers everything. None of them pay for dental work, vision care, hearing aids, or long-term care (nursing home or home health aide). If you need those services, you either pay out of pocket or buy a separate policy.

When You Can Buy Medigap Without Health Questions

The best time to buy Medigap is during your Medigap Open Enrollment Period, which is six months long and starts the month you turn 65 and are signed up for Medicare Part B. During this window, insurance companies cannot ask about your health history, cannot deny you coverage, and cannot charge you more because of a pre-existing condition. This is called "may provide issue" protection.

If you miss this window, you can still buy Medigap, but an insurance company can ask detailed health questions and can refuse to sell you a plan or charge you a higher price based on your answers. Some states have additional windows where you get may provide issue protection — for example, if you drop a Medicare Advantage plan within a certain timeframe, you may be able to buy Medigap without health questions. Your State Health Insurance information Program (SHIP) can tell you what windows explore where you live.

Outside of may provide issue periods, explore for Medigap is like explore for any other health insurance: the company reviews your medical history and decides whether to accept you and at what price.

How Medigap Premiums Work and What Affects Price

You pay a monthly premium to the Medigap insurance company, separate from your Medicare Part B premium. The price varies by plan letter, by the company you choose, by your age, and by where you live. A Plan G from Company A might cost $150 a month in one county and $180 in another, or $200 if you buy it at age 70 instead of age 65.

Insurance companies use three different methods to set prices as you age. Community-rated plans charge everyone the same price regardless of age. Issue-age-rated plans charge based on your age when you buy the plan and do not increase as you get older. Attained-age-rated plans increase in price every year as you age. Most plans are attained-age-rated, which means your premium will go up over time.

Some states regulate how much insurance companies can raise premiums each year. Others do not. Your SHIP office can tell you which pricing method each company in your area uses and what rate increases have been in the past.

Switching Plans or Dropping Medigap

You can switch from one Medigap plan to another, but the rules depend on whether you are in a may provide issue period. During your six-month Medigap Open Enrollment Period, you can switch to any plan from any company without health questions. Outside that window, you can still switch, but the new company can ask health questions and can deny you or charge more.

If you want to switch to a Medicare Advantage plan instead, you have a window to do so. If you then want to switch back to Medigap, you may or may not get may provide issue protection depending on your state and how long you were in Medicare Advantage. This is one reason to think carefully before leaving Medigap — getting back in can be harder and more expensive.

You can drop your Medigap plan at any time by telling the insurance company in writing. Medicare will continue, and you will be responsible for all the copayments and deductibles that Medigap was paying. If you drop Medigap to join a Medicare Advantage plan, make sure the Medicare Advantage plan is active before your Medigap ends, so you do not have a gap in coverage.

What to Ask Your Doctor and Insurance Company

Before you buy a Medigap plan, ask your current doctors whether they accept Medicare and whether they have any limits on how many Medicare patients they see. Most doctors do accept Medicare, but some do not, and Medigap only helps if your doctor takes Medicare.

Ask the Medigap insurance company directly what the premium will be in five years and ten years — they cannot predict exactly, but they can tell you the method they use to raise prices and what the trend has been. Ask whether the plan has any limits on how many days in the hospital it covers or any other caps. Ask what you need to do to file a claim if a doctor's office does not submit the claim to Medicare and Medigap automatically.

If you are considering dropping Medigap to join a Medicare Advantage plan, ask your SHIP office what may provide issue rights you would have if you wanted to switch back to Medigap later. The answer depends on your state and how long you stay in Medicare Advantage.

When to Seek Help From Your State

Contact your State Health Insurance information Program (SHIP) if an insurance company denies your Medigap process or charges you a price that seems much higher than other companies in your area. SHIP counselors are free and work for your state, not for insurance companies. They can tell you whether the denial or price is legal under your state's rules and can help you file a complaint if it is not.

Call SHIP also if you are confused about which plan letter to choose, whether you should switch plans, or what may provide issue windows explore to you. They can walk through your situation and explain your options. You can find your state's SHIP by searching "[your state] SHIP" or by calling 1-800-MEDICARE and asking for the referral.

If you have a complaint about how a Medigap company is treating you — for example, if they are not paying claims they should pay — SHIP can help you file a complaint with your state insurance commissioner.

Frequently Asked Questions

Can I have both Medigap and Medicare Advantage at the same time?

No. You choose one or the other. If you have Medicare Advantage, buying a Medigap plan is a waste of money because Medicare Advantage already includes coverage for copayments and deductibles. If you have Medigap, you cannot use a Medicare Advantage plan.

Does Medigap cover prescription drugs?

No. Medigap does not cover prescriptions. You need a separate Part D prescription drug plan, which you can buy from any insurance company. You can have both Medigap and Part D at the same time.

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

Your Medigap plan stays active, but the premium may change because prices vary by state. Contact your insurance company to find out. You can also shop for a new Medigap plan in your new state, but outside the may provide issue period, the new company can ask health questions.

Is there a Medigap plan that covers everything Medicare does not?

No plan covers everything. Plan G covers the most — it pays the Part B deductible, coinsurance, and copayments — but it does not cover dental, vision, hearing, or long-term care. You would need separate coverage for those services.

Can I buy Medigap if I have a pre-existing condition?

Yes, during your six-month Medigap Open Enrollment Period starting when you turn 65 and enroll in Part B. During that window, your health history does not matter. Outside that window, an insurance company can deny you or charge more based on your medical history.