What supplemental insurance does and why you might need it
Supplemental insurance (also called Medigap) pays some of the costs that Original Medicare leaves you responsible for — copayments, coinsurance, and deductibles. Medicare covers a lot, but not everything. When you see a doctor, you typically owe a copay. When you stay in the hospital, you owe a deductible. Supplemental insurance picks up some or all of those bills.
Whether you need it depends on your situation. If you have limited savings and worry about unexpected medical bills, supplemental insurance can protect you. If you have other coverage through a current or former employer, or if you are on Medicaid, you may not need it. The choice is yours — Medicare does not require you to buy supplemental insurance, and you can decide not to.
The trade-off is straightforward: you pay a monthly premium to the insurance company, and they pay your out-of-pocket costs when you use care. The premium varies by age, location, and which plan you choose. Younger people pay less; older people pay more. Some states have higher premiums than others.
Key Takeaways
- Supplemental insurance covers the copayments, coinsurance, and deductibles that Original Medicare requires you to pay.
- There are ten standardized Medigap plans (A through N), each covering a different combination of costs, so you choose based on what out-of-pocket expenses you want to avoid.
- You can only buy supplemental insurance during your initial enrollment window (the six months after you turn 65 and sign up for Medicare Part B), or you may face higher premiums or denial.
- Supplemental insurance works only with Original Medicare, not with Medicare Advantage plans, which have their own network and cost structure.
- Monthly premiums range widely depending on your age, location, and plan choice, and you should compare quotes from multiple insurers before deciding.
The ten standardized Medigap plans and what each covers
All supplemental insurance plans are standardized by federal law, meaning Plan G from one company covers exactly the same things as Plan G from another company. The difference is price. The ten plans are labeled A, B, D, G, K, L, M, N, and two high-deductible versions of G and N. Each plan covers a different set of costs.
Plan G is the most popular choice for new enrollees. It covers your Part B coinsurance (the percentage you owe after Medicare pays its share), your Part B deductible, and most other out-of-pocket costs. It does not cover your Part B excess charges — the amount a doctor can bill above Medicare's approved amount — but few doctors charge those anymore. Plan G typically costs $100 to $200 per month, depending on your age and where you live.
Plan N is less expensive than Plan G but requires you to pay small copayments at the doctor's office and emergency room. It covers your hospital coinsurance and Part B deductible but not excess charges. If you see doctors frequently, Plan N may cost you more out of pocket overall, even though the monthly premium is lower.
Plan A is the cheapest option and covers basic costs: hospital coinsurance and your Part B deductible. It does not cover your Part B coinsurance, so you still owe a percentage of each doctor visit. Plan A is rarely chosen by people with moderate or high medical use.
Plans B, D, K, L, and M exist but are chosen less often. Plan B covers the Part B deductible but not coinsurance. Plans K and L cover a percentage of costs rather than all of them, which means you still have some out-of-pocket risk. Plan D and Plan M are rarely sold to new enrollees. The high-deductible versions of Plans G and N have much lower monthly premiums but require you to pay a yearly deductible (around $2,700 for Plan G, less for Plan N) before the plan pays anything.
When you can buy supplemental insurance and what happens if you miss the window
You have the strongest protection when you buy supplemental insurance during your initial enrollment period, which is the six months starting the month you turn 65 and sign up for Medicare Part B. During this window, insurance companies cannot deny you coverage or charge you more based on your health history. This is called may provide issue rights.
If you miss this window, you can still buy supplemental insurance, but the rules change. Insurance companies can ask about your health and deny you coverage if you have certain conditions. They can also charge you a higher premium to make up for the risk. Some people wait to buy supplemental insurance and later find out they cannot get it, or can only get it at a much higher cost.
There are limited exceptions to this rule. If you were covered by an employer health plan when you turned 65, you may have additional time to buy supplemental insurance without penalty. If you lose that employer coverage, you have a window to enroll in supplemental insurance with may provide issue. You will need to show proof that you had employer coverage and when it ended.
If you are already on Medicare and did not buy supplemental insurance, you can still buy it later, but you should do so as soon as you decide you want it. The longer you wait, the more expensive it becomes, and the harder it is to get approved.
Supplemental insurance versus Medicare Advantage: which works with which
Supplemental insurance works only with Original Medicare (Part A and Part B). If you choose a Medicare Advantage plan instead, you cannot use supplemental insurance. Medicare Advantage plans are an alternative to Original Medicare offered by private insurance companies. They typically have lower premiums but require you to use doctors in their network and may have higher copayments.
The two approaches are fundamentally different. With Original Medicare plus supplemental insurance, you can see any doctor who accepts Medicare, and your supplemental plan covers most of your out-of-pocket costs. With Medicare Advantage, you are locked into a network, and your out-of-pocket costs depend on the plan's design — some plans cover more, some less.
You cannot have both at the same time. When you enroll in Medicare Advantage, you automatically drop Original Medicare. If you later want to switch back to Original Medicare and buy supplemental insurance, you may not have may provide issue rights, and you may face higher premiums or denial.
How to compare plans and get quotes
Start by deciding which plan type makes sense for your situation. If you want the broadest coverage and do not want to worry about copayments, Plan G is the standard choice. If you are willing to pay small copayments to save on your monthly premium, Plan N is worth comparing. If you are very healthy and rarely see a doctor, a high-deductible plan might save you money overall.
Once you have chosen a plan letter, get quotes from multiple insurance companies. The same plan costs different amounts from different insurers, and the difference can be $50 to $100 per month or more. You can get quotes by calling insurers directly, visiting their websites, or using a broker who represents multiple companies. Medicare.gov has a tool that shows you plans available in your area, though it does not show prices.
When comparing quotes, look at the monthly premium, but also ask about rate increases. Some companies raise rates slowly; others raise them sharply. Ask whether the company uses age-based pricing (your premium goes up as you get older) or issue-age pricing (your premium stays based on the age you were when you enrolled). Issue-age pricing is usually better for people who plan to stay with the same company for many years.
Do not choose based on price alone. Check the company's customer service ratings and complaint history. You can see complaints filed with your state insurance commissioner on the National Association of Insurance Commissioners website. A company with a slightly higher premium but better service may be worth the extra cost.
What supplemental insurance does not cover
Supplemental insurance covers the gaps in Original Medicare, but it does not cover everything. It does not cover long-term care — nursing home stays, assisted living, or in-home care. It does not cover dental, vision, or hearing aids. It does not cover prescription drugs; that is what Medicare Part D is for.
If you need long-term care coverage, you would buy a separate long-term care insurance policy, and you should do that while you are still relatively young and healthy. If you need dental or vision coverage, you can buy standalone plans for those, though they are limited and often have waiting periods.
Supplemental insurance also does not cover care outside the United States. If you travel internationally and need medical care, you are responsible for the full cost. Some people buy travel health insurance for trips abroad, but that is separate from supplemental insurance.
Questions to ask your doctor and insurance company
Before you choose a plan, ask your doctor how often you typically need to see them and whether you take many prescription medications. This helps you estimate your out-of-pocket costs under different plans. If you see a specialist regularly, ask whether they accept Medicare and what your copay would be.
Ask your insurance company directly: What is the monthly premium? Does the premium increase with age, and if so, by how much? What is the process for paying claims — do I pay the doctor and submit a claim, or does the doctor bill the insurance company directly? How long does it take to process a claim? What is your customer service phone number, and what are the hours?
Ask whether the company offers any discounts, such as for paying by automatic bank withdrawal or for enrolling in multiple plans. Some companies offer small discounts, though they are not common.
Frequently Asked Questions
Can I switch from one supplemental plan to another?
Yes, you can switch plans at any time, but the rules depend on your health. If you switch to a plan with less coverage (for example, from Plan G to Plan N), the new company cannot deny you or charge you more based on health. If you switch to a plan with more coverage, the new company can ask about your health and may deny you or charge more. You have may provide issue rights only during your initial enrollment period.
What happens to my supplemental insurance if I move to a different state?
Your supplemental insurance stays active, but the premium may change. Some companies charge different rates in different states. You can keep your current plan and company, or you can switch to a different company that operates in your new state. If you switch, the new company can ask about your health unless you are within your initial enrollment period.
Do I need supplemental insurance if I have Medicaid?
No. Medicaid covers many of the costs that supplemental insurance would cover, so buying supplemental insurance would be redundant and wasteful. If you have both Medicare and Medicaid, Medicaid is your primary coverage for costs that both programs cover.
What if I cannot afford the monthly premium?
Some states have programs that help pay supplemental insurance premiums for people with low income. Contact your State Health Insurance information Program (SHIP) to learn whether you may have access to. You can find your state's SHIP by calling 1-877-839-2675 or visiting shiptalk.org. If you cannot afford supplemental insurance, you can still use Original Medicare without it, though you will have more out-of-pocket costs.
Can I buy supplemental insurance if I have a pre-existing condition?
During your initial enrollment period, yes — insurance companies cannot deny you or charge you more based on your health. If you miss that window, insurance companies can ask about your health and may deny you coverage or charge a higher premium. The longer you wait after turning 65, the harder it becomes to get approved.