There is no single "best" Medicare supplement — the right one depends on your health needs, budget, and where you live
A Medicare supplement (also called Medigap) fills gaps in what Original Medicare covers — things like copayments, coinsurance, and deductibles. Ten standardized plans exist, labeled A through N. Plan G covers the most, Plan A the least. Plan N costs less but has higher copays at the doctor's office. The "best" plan is whichever one balances what you actually use the doctor for against what you can afford to pay each month.
Your choice matters most in two ways: how much you spend on premiums (the monthly payment), and how much you spend when you go to the doctor. A plan with a low premium might have high copays; a plan with high premiums might save you money if you see doctors often. The right answer is different for someone who visits a cardiologist monthly than for someone who sees a doctor once a year.
Key Takeaways
- Plan G covers the most gaps in Medicare and is the most common choice for people newly turning 65, though it costs more per month than other plans.
- Plan N costs less per month but charges copays at doctor visits and urgent care, so it works better for people who rarely see a doctor.
- Your state, your age, and the insurance company you choose all affect your monthly premium, sometimes by hundreds of dollars for the same plan.
- You can switch plans during the annual open enrollment period (October 15 to December 7), but only if you are still in Original Medicare.
- The best time to buy your first supplement is within six months of turning 65, when insurers cannot deny you or charge more based on your health.
How the ten plans compare on what they cover
All ten plans cover the same things within each plan letter — Plan G from one company covers exactly what Plan G from another company covers. The difference is price, not coverage. Plans A, B, D, G, M, and N are the ones most people choose. Plans C, F, K, and L are closed to new people turning 65 after 2020, though people already on them can keep them.
Plan G covers everything except the Part B deductible (the first $240 you pay each year for doctor visits). Plan A covers less — it does not cover the Part B deductible or any copays for emergency room visits. Plan N covers most things but charges you $20 copays at the doctor and $50 at urgent care. Plan M covers about 75 percent of costs and costs less than G or A, but you pay coinsurance on hospital stays and skilled nursing.
The real question is not which plan covers the most, but which one matches how you use healthcare. If you have a chronic condition and see specialists regularly, Plan G usually costs less overall because the monthly premium is higher but the copays are zero. If you are healthy and rarely see a doctor, Plan N or Plan A might cost less overall because you save money on premiums, even though you pay when you do go.
What your monthly premium depends on
The same plan costs different amounts depending on where you live, which insurance company sells it, and how old you are. A Plan G might cost $150 a month in one state and $250 in another. The same plan from two different insurers in the same town might differ by $50 or more. Age matters too — most companies charge more as you get older, though the increase varies.
Some states regulate how much insurers can charge based on age. In "community rating" states, your age does not affect your premium much. In "issue-age rating" states, your age when you first buy the plan locks in your rate, and it rises slowly over time. In "attained-age rating" states, your premium rises as you age, sometimes significantly. Your state's insurance commissioner's office can tell you which method your state uses.
Shopping around matters. Call or visit websites for at least three insurers in your area selling the same plan letter. The difference in what you pay can add up to thousands of dollars over several years. Some insurers offer discounts if you pay the full year upfront, or if you also buy a Part D prescription plan from them.
When you can buy a supplement and when you cannot
The best time to buy is within six months of the date you first sign up for Medicare Part B. During this window, insurers must sell you any plan you want and cannot charge more or deny you based on your health history. This is called open enrollment for supplements, and it is different from the Medicare annual enrollment period.
If you miss this window, you can still buy a supplement, but insurers can refuse to sell to you or charge more if you have a health condition. Some states have protections that limit this, but not all. You can also switch plans during the yearly Medicare open enrollment period (October 15 to December 7), but only if you stay in Original Medicare. If you switch to a Medicare Advantage plan, you lose your supplement.
If you are currently on a Medicare Advantage plan and want to switch to Original Medicare plus a supplement, you have a limited window to do so without facing health underwriting. Talk to your current insurer or your state health insurance counselor about the exact dates that explore to you.
How to compare plans side by side
Start by listing the plans you are considering — usually Plan G, Plan N, and Plan A. For each plan, write down the monthly premium from at least two insurers. Then write down the copays: what you pay at a doctor visit, at urgent care, at the emergency room, and for hospital stays. Multiply the copays by how often you think you will use each service in a year.
Add the annual premiums (monthly premium times 12) to the estimated copays. That total is roughly what the plan will cost you in a year. Do this for each plan and each insurer. The lowest total is usually the best choice for your situation, though you may also want to consider whether you have a preferred doctor and whether that doctor is in the insurer's network (though most supplements do not use networks the way Medicare Advantage plans do).
You can also use the Medicare Plan Finder tool on Medicare.gov, which lets you enter your zip code and see plans available in your area with their premiums. It does not show copays, so you will need to call insurers directly for that information. Your State Health Insurance information Program (SHIP) offers free counseling to help you compare — search "[your state] SHIP" online or call 1-800-MEDICARE to find your local office.
Why Plan G is the most common choice
Plan G covers nearly everything Original Medicare does not — copays, coinsurance, and deductibles — except the Part B deductible. For people newly turning 65, it is often the best value because the monthly premium is predictable and you know exactly what you will pay at the doctor: nothing. If you see doctors regularly or have a chronic condition, the zero copays usually save you money compared to plans with lower premiums but higher copays.
Plan G also protects you against surprise costs. If you need an unexpected hospital stay or specialist visit, you are not hit with a bill. That peace of mind matters to many people, especially those on a fixed income. The trade-off is that you pay more per month than you would for Plan N or Plan A.
Plan G is not the right choice for everyone. If you rarely see a doctor and are in good health, you might pay less overall with Plan N or Plan A, even though those plans have copays. The key is to do the math for your own situation rather than assuming the most popular plan is the best for you.
Special situations: working past 65, Medicaid, and other coverage
If you are still working and have health insurance through your job, you may not need a supplement right away. When you do retire and lose that coverage, you have a window to buy a supplement without health underwriting — usually 63 days after your work coverage ends. Do not wait longer than that, or you may face denials or higher premiums.
If you also have Medicaid, some supplements work better than others. Medicaid covers some costs that supplements do not, so you may not need a comprehensive plan like G. Talk to your state Medicaid office or your SHIP counselor about which plan makes sense if you have both Medicare and Medicaid.
If you have Veterans Affairs (VA) coverage, you can still buy a supplement, but the supplement will not cover costs the VA already covers. Some veterans find a supplement useful anyway for care outside the VA system. If you are a federal retiree with the Federal Employees Health Benefits Program (FEHB), you can keep that coverage alongside Medicare and a supplement, though you will pay premiums for all three.
Frequently Asked Questions
Can I switch supplement plans if I change my mind?
Yes, during the annual Medicare open enrollment period (October 15 to December 7) you can switch to a different plan, even if you have a health condition. Outside this window, insurers can deny you or charge more based on your health. Your best protection is to choose carefully the first time, within six months of turning 65.
What happens to my supplement if I switch to Medicare Advantage?
Your supplement becomes useless — Medicare Advantage plans do not work with supplements. If you later switch back to Original Medicare, you will need to buy a new supplement, and insurers can deny you or charge more based on your health unless you are within a protected window. Think carefully before switching away from Original Medicare plus a supplement.
Do I need a supplement if I have good health and rarely see a doctor?
Not necessarily. Some people stay on Original Medicare alone and pay copays and deductibles out of pocket. This works if you have savings to cover unexpected costs. A low-premium supplement like Plan A or N might still be worth it for the protection against a major hospital stay, which can cost thousands even with Medicare.
How much does a supplement cost per month?
Premiums vary widely by state, insurer, age, and plan. Plan A might cost $100 to $150 per month, while Plan G might cost $200 to $350. Call insurers in your area for exact prices. Your SHIP counselor can also help you find current rates without having to call multiple companies.
Can an insurer drop me from my supplement plan?
Insurers can stop selling a particular plan in your state, but if they do, they must offer you another plan at the same or lower premium. They cannot drop you individually because of your health or claims history. Once you own a supplement, you have strong protections against losing it.