Choosing a Medigap plan — the lettered plans decoded

Reviewed by Sarah Chen, CFP

There are 10 standardized Medigap plan letters, but most people choose from just two or three. According to CMS, Plan G and Plan N are the most popular options for new enrollees because they offer strong coverage at reasonable premiums. The best time to buy is during your parent's six-month Medigap Open Enrollment period, when insurance companies cannot deny coverage or charge more for health conditions.

At some point during your research into Medigap, you're going to see a chart with plans listed by letter. Plan A. Plan B. Plan C. Plan G. Plan N. And you're going to think: why are there so many, and how am I supposed to know which one is right for my parent?

The answer is less mystical than it seems. The letters don't represent different companies or different quality levels. They represent different combinations of benefits. Once you understand what each letter covers, the choice becomes much simpler.

This is the kind of information that looks complicated until it's explained clearly, and then it's just a series of trade-offs between cost and coverage. And trade-offs are something every adult child can evaluate.

Why Each Plan Letter Exists: Covering Different Gaps

Each letter represents a specific combination of benefits that fill the gaps in Original Medicare's coverage.

Medicare standardized Medigap plans decades ago so that people could compare them easily. Any Aetna Plan G has exactly the same benefits as any Humana Plan G or any other insurer's Plan G. The government sets what each letter covers. Insurance companies can't change the benefits. What they can change is the monthly premium they charge.

This standardization exists because Medigap plans need to cover different categories of gaps. Different people have different medical needs and different financial situations. Some people want maximum coverage and are willing to pay more. Some people want lower monthly premiums and are comfortable with a few out-of-pocket costs.

The gaps they're covering are specific things: the hospital deductible from Part A, copays for doctor visits, coinsurance for hospital stays, coinsurance for skilled nursing facilities, and various other cost-sharing amounts that Original Medicare imposes. Each Medigap plan covers different combinations of these gaps.

No plan is universally "best." Plan G isn't better than Plan A in any absolute sense. Plan G covers more, so it costs more. Plan A covers less, so it costs less. Which one is better depends on your parent's health situation, their expected medical costs, and their financial priorities.

The Most Common Plans: A, G, N

Plan G offers the most comprehensive coverage for new enrollees, while Plan N costs less but requires small copays for some visits.

If you're trying to cut through all the options, focus on these three because they represent the main choices most people actually consider.

Plan A is the bare-bones option. It costs the least per month. It covers some gaps but not all of them. Plan A covers the hospital coinsurance, which is significant if your parent is hospitalized for a long time. It covers blood transfusions and some skilled nursing facility coinsurance. But it doesn't cover the Part B deductible, and it has copays for doctor visits and emergency room visits. Plan A works for people who are relatively healthy and don't expect frequent doctor visits or hospital stays.

Plan G covers much more. It covers the Part B deductible, the hospital deductible, copays and coinsurance for doctors and hospital care, skilled nursing facility coinsurance, and most other costs except foreign travel emergency care. Plan G is what most people think of when they picture comprehensive supplemental coverage. Your parent pays their monthly Plan G premium and then most medical costs are covered. Plan G costs more per month than Plan A, often $50 to $100 more depending on age, state, and insurance company. But your parent's out-of-pocket costs during the year are likely much lower because Plan G covers so much.

Plan N is the middle ground. It's cheaper than Plan G but more expensive than Plan A. Plan N covers most gaps but not all. Your parent pays a copay when they see the doctor, and they might pay a small copay for emergency room visits. But Plan N covers the Part B deductible, hospital costs, and skilled nursing facility costs. For people who want reasonable protection without paying the highest premiums, Plan N is often the answer.

Then there are other plans like Plan K or Plan L, which have a different structure where your parent has a higher annual out-of-pocket limit before Medigap starts covering everything. These plans are rarer and often used by people with very specific situations. And Plan M exists but is rarely chosen because it's more expensive than Plan A but covers less than Plan G.

Most people end up choosing Plan A, Plan G, or Plan N because these three represent the actual choices people face. Beyond these three, you're dealing with edge cases and very specific situations.

The Coverage Details That Matter

The differences between plans come down to whether they cover the Part B deductible, Part B excess charges, and skilled nursing facility coinsurance.

Let's get specific about what these plans actually cover because the differences matter to your parent's actual healthcare costs.

Hospital stays come with a deductible under Part A. Your parent pays this deductible once per benefit period. If they're hospitalized multiple times but those stays are part of the same benefit period, they only pay the deductible once. After the deductible, they have daily copays if they stay longer than a certain number of days. Plan A covers some of these copays. Plan G and Plan N cover all of these copays. So if your parent is hospitalized for two weeks, they're looking at significant costs under Plan A, while they're mostly covered under Plan G.

Skilled nursing facility care is covered under Part A if your parent qualifies. The requirements are strict—they need a qualifying hospital stay first—but if they do qualify, they can go to a skilled nursing facility for rehabilitation. The facility has daily copays for days 21 through 100. If your parent goes for a month of rehabilitation, that's about 10 days of copays at maybe $200 a day. That's $2,000 out of pocket under Plan A. Plans G and N cover these copays, so your parent pays little or nothing.

Doctor visits and other outpatient care generate copays and coinsurance. Under Original Medicare Part B, your parent typically pays 20% coinsurance after they meet their deductible. If your parent sees a cardiologist and the visit costs $200, they might pay $40 out of pocket. If they see the doctor ten times a year, that's $400 per year just in coinsurance. Plan A doesn't cover these copays, so your parent is paying them. Plan G and Plan N cover most of these, so your parent's out-of-pocket costs are much lower.

Blood transfusions are a weird one, but it matters. Medicare Part B covers blood transfusions, but your parent pays the cost of the first three units of blood. Hospitals charge hundreds of dollars per unit. If your parent needs a transfusion, this could be thousands of dollars. Plan A covers these costs. Plan G and N also cover them.

Foreign travel emergency coverage is a benefit some Medigap plans include. If your parent travels internationally and has a medical emergency, their plan will cover up to a certain amount of the cost. Plans like G include this. Plans like A don't. If your parent travels a lot, this might matter. If not, it's irrelevant.

The key patterns are that Plans G and N cover most gaps and most costs, while Plan A leaves your parent responsible for some meaningful copays and coinsurance. The choice comes down to whether your parent prefers lower monthly premiums with some out-of-pocket costs, or higher monthly premiums with predictable and low out-of-pocket costs.

The Monthly Cost Reality

Monthly premiums for the same plan letter can vary by hundreds of dollars between insurance companies, because the benefits are standardized but the pricing is not.

Here's what people get wrong about Medigap pricing: they look at the monthly premium for Plan A and think "I'll save money compared to Plan G." Maybe Plan A is $100 a month and Plan G is $200 a month. That's $1,200 more per year for Plan G. That sounds expensive.

But then they have a doctor's visit. Plan A charges them a copay. Plan G doesn't. They have another doctor's visit. Plan A charges another copay. Plan G doesn't. Over the course of a year, someone with multiple chronic conditions might pay $500 or $1,000 in copays under Plan A that they wouldn't pay under Plan G. Suddenly the extra $1,200 in premiums for Plan G doesn't look so bad. For someone with serious health conditions, Plan G's higher premium is more than paid for by the lower out-of-pocket costs.

The other pricing reality is when your parent applies. If your parent applies during their 63-day Open Enrollment Period right after turning 65, they get the best rates. If they wait until 70, the rates are higher. If they wait until 75, higher still. In states with age-rated pricing, your parent's age determines the price. In community-rated states, age doesn't matter as much.

Insurance companies charge different premiums for the same plan. An Aetna Plan G might be $180 a month while a Humana Plan G is $160 a month. The benefits are identical, but the price differs. You compare quotes from multiple companies and pick the lowest price.

There's also something called "issue-age rating" in some states, which means your premium is based on how old you are when you buy the plan and then increases each year with inflation. There's "attained-age rating," which means your premium depends on how old you are each year. There's "community rating," which means everyone pays the same regardless of age. The rating system is determined by your state, and it affects how expensive Medigap will be over time.

The bottom line is that Medigap premiums vary by location, company, age, and rating method. Your parent needs to shop and compare quotes. But they need to do it during the Open Enrollment Period when they have the most options.

Making the Plan Comparison That Matters

Compare the same plan letter across multiple insurance companies, because benefits are identical but premiums are not.

Start by asking your parent about their health. Are they managing multiple chronic conditions? Do they see specialists regularly? Do they expect ongoing medical treatment? If the answer is yes to most of these, Plan G probably makes sense despite the higher premium because the out-of-pocket costs under other plans will quickly exceed the premium difference.

Is your parent generally healthy with just one or two preventive doctor visits a year? Do they rarely need specialist care or hospital stays? Are they budget-conscious and okay with paying some copays? Then Plan A or Plan N might be the better choice because they'll rarely trigger the gaps that Plans G covers.

Ask about prescription medications. Medigap doesn't cover prescriptions, so your parent also needs a Part D plan. Some medications are expensive. Some are cheap. If your parent takes expensive medications, make sure the Part D plan you choose covers those drugs at a reasonable cost. This is separate from the Medigap choice but equally important.

Ask whether your parent travels internationally. If they do, foreign travel emergency coverage matters and limits your options. If not, it's just extra you're paying for.

Get quotes from multiple insurance companies for the plans you're considering. A Plan G from Company A might be $180 a month while Company B charges $220 for the same plan. That's $480 per year difference for identical coverage. Shop it.

Then sit down with your parent and explain the trade-offs clearly. Plan A costs less per month but leaves them responsible for some out-of-pocket costs. Plan G costs more per month but covers most costs. Plan N is in between. Your parent is the decision-maker here because it's their health, their money, and their comfort level with the trade-offs.

Don't get overwhelmed by the other plan letters. Most people genuinely don't need them. Most people find their answer in Plans A, G, or N. These represent the actual choices people make, and once you understand them, the decision becomes straightforward. You're balancing monthly cost against out-of-pocket costs, and your parent's health situation tells you which direction to lean.

Frequently Asked Questions

What is the best Medigap plan for most people?

Plan G is the most popular choice for new enrollees because it covers nearly all of Original Medicare's out-of-pocket costs except the annual Part B deductible (currently $240 in 2024). Plan N is a good alternative if your parent wants a lower premium and does not mind small copays for office visits.

Can my parent switch Medigap plans later?

They can apply to switch at any time, but outside the initial Open Enrollment period, insurance companies can deny coverage or charge higher premiums based on health status. In some states, there are annual open enrollment windows. Check your state's rules.

Does Medigap cover prescription drugs?

No. Medigap plans do not cover prescription drugs. Your parent needs a separate Medicare Part D plan for drug coverage.

How much does Medigap cost per month?

Monthly premiums range from roughly $50 to over $300 depending on the plan letter, the insurance company, your parent's age, and your state. Plan G typically costs between $100 and $250 per month. Always compare quotes from multiple companies for the same plan letter.

How To Help Your Elders is an educational resource. We do not provide medical, legal, or financial advice. The information in this article is general in nature and may not apply to your specific situation. If you are concerned about a loved one's cognitive health or safety, consult with their healthcare provider or contact your local Area Agency on Aging for guidance and support.