Medicare Parts A, B, D, and Medigap: What Each One Covers
Oct 13, 2026
My client needed to sign her mother up for Medicare but didn’t know anything about it. So, I walked her through Medicare Parts A, B, C, and D. I explained Medigap, also known as Medicare Supplement Insurance. My client needed information on each of the parts of Medicare and Medigap, in order to make the best decision for her mother.
In this post, I’ll be explaining Medicare Parts A, B, and D, as well as Medigap. There will be separate posts explaining Medicare Part C, as well as how to sign up for Medicare.
What is Medicare?
Medicare is health insurance provided by the federal government to people who are 65 or older or under 65 who qualify due to disability or specific illness who can legally receive federal benefits.
Who can get Medicare?
There are multiple requirements that must be met to receive Medicare benefits. First, you must be eligible to, or allowed to, receive benefits from the federal government, like living lawfully in the U.S. Once that requirement is met, you qualify for Medicare at the age of 65. You may be eligible for Medicare if you’re under 65 with a qualifying disability or specific illness.
What are your Medicare options?
When you first sign up for Medicare, and during certain times of the year, you can choose how you get your Medicare coverage. There are two main ways to get Medicare: Original Medicare, which is Part A (hospital insurance) and Part B (medical insurance), or Medicare Advantage, also known as Part C. If you have Original Medicare, you have the option to add Medicare Part D (drug coverage).
What are the parts of Medicare, and what do they cover?
There are four parts of Medicare: Part A, Part B, Part C, and Part D. Let’s go into what each of them covers one by one.
Medicare Part A helps cover:
- Inpatient care in hospitals
- Skilled nursing facility care
- Hospice care
- Home health care (some is covered by Part A and some by Part B)
Medicare Part B helps cover:
- Medically necessary services from doctors and other health care providers
- Outpatient care (like same-day surgeries where you go home after and don’t stay in the hospital overnight)
- Home health care (some is covered by Part A and some is covered by Part B)
- Durable medical equipment (like wheelchairs, walkers, and hospital beds)
- Mental health services
- Limited outpatient prescription drugs
- Many preventive services, like screenings and vaccines
- Other medical services
To find out if Medicare covers a service that isn’t on this list, you can go to medicare.gov/coverage.
Medicare Part C (Medicare Advantage) is a Medicare-approved plan from a private company that offers an alternative to Original Medicare for your health and drug coverage. There’s a lot to learn about Medicare Advantage, so that will be covered in a separate post.
Medicare Part D helps cover:
- Prescription drugs
What is Medicare Supplement Insurance, and why does it matter?
Medicare Supplement Insurance, also called Medigap, is extra insurance you can buy from a private company to help pay your out-of-pocket costs that Original Medicare doesn’t cover, like copays (the set, flat rate that you pay for an individual visit at the time of the visit), coinsurance (a shared cost with Medicare, where you pay percentage of the cost of the visit or procedure and insurance pays the rest), and deductibles (the amount of money you pay yourself before insurance covers services). To understand these terms better, read HMO vs PPO, Premiums, Deductibles…Finally Explained.
Medigap matters because Original Medicare doesn’t pay all of the costs for covered health care services and supplies. With Original Medicare, you’re generally responsible for some of the costs for approved services. Medicare pays its share of the approved service, and then your Medigap policy would help pay your share, lowering your cost. It’s important to note that Medigap only pays for services covered by Medicare. If Medicare doesn’t cover it, Medigap doesn’t either, with the exception that some plans cover some emergency care in another country.
A Medigap policy is completely different from a Medicare Advantage Plan because it helps cover costs not paid for by Original Medicare. Not only is Medigap not a Medicare Advantage Plan, but also you can’t get a Medigap policy if you have a Medicare Advantage Plan. It only works with Original Medicare.
Medigap policies don’t cover prescription drugs; however, if you have limited income and resources, you may qualify for a program called Extra Help that helps pay for some Medicare drug costs.
If I want Medigap, when should I sign up?
The best time to get a Medigap policy is during your Medigap Open Enrollment Period. It’s the 6-month period that starts the first month you have Medicare Part B and you’re 65 or older. During this time, you can buy any Medigap policy sold in your state, even if you have health problems. And, as long as you pay your Medigap plan premium and Part B premium, you’ll keep your policy, even if you have health problems. Your premium is the amount you pay each month to have access to your health insurance plan.
This is very important! During Medigap Open Enrollment, an insurance company can’t refuse to sell you any of the medical policies it offers, and it can’t decide whether to accept your application or deny you coverage due to pre-existing health problems.
If you’re under 65, you may not be able to buy a Medigap policy, or you may have to pay more.
What happens if I miss my Medigap Open Enrollment?
If you miss your Medigap Open Enrollment, you may not be able to buy a policy, may have to pay more for a policy, or may have fewer policy options available to you. On top of that, the insurance company is allowed to deny you a policy if you don’t meet its medical requirements.
If you’re able to buy a Medigap policy after the Open Enrollment Period or want to switch policies later, it may cost more.
Now, you may have Medigap protections, called guaranteed issue rights, in certain situations when insurance companies can’t deny you certain Medigap policies.
You may also have a “trial right.” A trial right is when you choose a Medicare Advantage Plan or the Program of All-Inclusive Care for the Elderly (PACE) when you first become eligible for Medicare at 65, and you choose to switch to Original Medicare within the first year. If you have a trial right, you may be able to get Medigap outside of the Medigap Open Enrollment Period.
Is there only one Medigap plan, or do I have options?
There are 10 standardized plans, meaning every plan with the same name, like “Plan A” for example, has the same coverage, no matter where you live or which insurance company you buy the policy from, with the exception of Massachusetts, Minnesota, and Wisconsin. These states offer different standardized plans. It’s important to compare the benefits of each plan because each plan covers a different percentage of the costs you’re responsible for. The plan options are Plans A-D, F, G, and K-N. Not everyone can buy Medigap Plans C or F. You can only buy Plans C or F if you were eligible for Medicare before January 1, 2020.
Is there anything I should know about before I choose my policy?
The only difference between policies with the same letter that are sold by different companies is price. This means that the premium can be significantly different depending on the company offering the policy, even though it’s for the same coverage.
There are many insurance companies that sell Medigap policies. You can go to the Medigap section of the Medicare website to look up what’s available in your area.
It can be confusing to deal with Medicare because of all of the letters, but now I’ve broken down Parts A, B, and D. The next two posts will cover Medicare Part C and how to sign up for Medicare. When you’re informed, you can make better health decisions for yourself and your loved ones.
Want to go further?
Decoding Healthcare opens October 31. It’s my four-step program that teaches you to understand your insurance coverage, verify every financial step, control communication, and navigate strategically.
Join the waitlist at healthcareuncomplicated.com/waitlist, and I’ll send you my free guide right away: 11 Questions To Ask Before You Pay Any Medical Bill. Waitlist members also get the early bird price.
Need help right now? I have three one-on-one spots open. Book a free 15-minute consult.
Coming in 2 Weeks: What is Medicare Part C (Medicare Advantage)?
Definitions
Medicare: Medicare is health insurance provided by the federal government to people who are 65 or older or under 65 who qualify due to disability or specific illness who can legally receive federal benefits.
Original Medicare: Original Medicare includes Parts A and B.
Medicare Advantage (Part C): Medicare Advantage is a Medicare-approved plan from a private company that offers an alternative to Original Medicare for your health and drug coverage.
Inpatient: Inpatient is when the hospital formally admits you with a doctor’s order.
Skilled nursing facility: A skilled nursing facility is a nursing facility with the staff and equipment to give skilled nursing care, and in most cases, skilled rehabilitative services and other related health services.
Hospice: Hospice care is given at the end of your life, when you have a life expectancy of 6 months or less and agree to receive comfort care, instead of care to cure.
Outpatient: Outpatient is when you’re getting emergency or observation services (which may include an overnight stay in the hospital or services in an outpatient clinic), lab tests or X-rays, without a formal inpatient admission, even if you spend the night in the hospital.
Durable medical equipment: Medical equipment that’s durable (can withstand repeated use), used for a medical reason, typically only useful to someone who’s sick or injured, used in your home, and expected to last at least 3 years.
Out-of-pocket costs: Out-of-pocket costs are costs you have to pay yourself.
Limited income and resources: Limited income and resources are amounts set by Medicare each year. See medicare.gov for current income and resource limits.
Extra Help: Extra Help is a program to help individuals with limited income and resources pay some Medicare drug costs.
Medigap Open Enrollment Period: The Medigap Open Enrollment Period is the 6-month period that starts the first month you have Medicare Part B and you’re 65 or older.
Premium: A premium is the amount of money you pay each month to have access to your health insurance coverage.
Pre-existing health problems: Pre-existing health problems are health problems that existed before you applied for health insurance.
Guaranteed issue rights: Guaranteed issue rights are situations when an insurance company can’t deny you a Medigap policy.
Trial right: A trial right is when you choose a Medicare Advantage Plan or the Program of All-Inclusive Care for the Elderly (PACE) when you first become eligible for Medicare at 65, and you choose to switch to Original Medicare within the first year.
Program of All-Inclusive Care for the Elderly (PACE): PACE is a Medicare and Medicaid program offered in many states that allows people who otherwise would need a nursing home-level of care to remain in the community, like a home or apartment, for as long as possible.
End-stage renal disease (ESRD): End-stage renal disease is the final, permanent stage of chronic kidney disease in which kidney function has declined to the point that the kidneys can no longer function on their own.
ALS: ALS stands for amyotrophic lateral sclerosis, also called Lou Gehrig’s disease. It’s a nervous system disease that affects nerve cells in the brain and spinal cord.
Observation services: Observation services are services you receive while being watched and treated for a short time, possibly even overnight, to check to see if you need to stay longer as an inpatient.
Late enrollment penalty: A late enrollment penalty is an additional amount you have to pay each month on top of your monthly premium because of not signing up for the insurance during one of the enrollment periods that don’t carry a penalty.
Initial Enrollment Period: The Initial Enrollment Period is the first range of time that you’re allowed to enroll.
Creditable prescription drug coverage: Creditable prescription drug coverage is prescription drug coverage that’s expected to pay, on average, at least as much as Medicare drug coverage (Part D).
State Health Insurance Assistance Program (SHIP): SHIP is a free, federally funded program that provides local, in-depth, objective insurance counseling for Medicare-eligible individuals, their families, and caregivers.
Service area: A service area refers to the geographic area where a person must live to be eligible to enroll in a health plan, and where the plan has in-network providers.
In-network providers: In-network providers are providers that have a contract with your insurance provider.
Medicaid: Medicaid is a joint federal and state program that helps with medical costs for some people with limited income and (in some cases) resources. Medicaid programs vary from state to state.
Nursing home-level of care: Nursing home-level of care is the point at which a person needs the kind of full-time care and supervision, both medical and non-medical, that’s normally associated with a nursing home.
Frequently Asked Questions
What’s the difference between Medicare Part A and Part B? Medicare Part A covers inpatient hospital care, skilled nursing facility care, hospice care, and some home health care, while Medicare Part B covers services from doctors and other health care providers, outpatient care, some home health care, durable medical equipment (like walkers and wheelchairs), mental health services, limited outpatient prescription drugs, many preventive services, as well as other medical services. Here’s the full list of covered services.
Who’s eligible for Medicare? In order to receive Medicare benefits you must either be a U.S. citizen or a U.S. national, or a lawful permanent resident (green card holder), or a Cuban-Haitian entrant (a special benefit eligibility category that applies to certain nationals of Cuba or Haiti), or lawfully living in the U.S. as a Compact of Free Association (COFA) migrant (citizens of the Republic of the Marshall Islands, the Federated States of Micronesia, or the Republic of Palau who meet certain requirements). If you meet these eligibility requirements, you must also be 65 or older or qualify with a disability or specific illness.
Can I get Medicare before I turn 65? Yes, if you meet certain requirements. This can include diagnoses of End-stage renal disease (ESRD), ALS, and some situations involving disabilities. See if you might be eligible for Disability
What’s the difference between inpatient and outpatient care? You’re an inpatient when the hospital formally admits you with a doctor’s order. You’re an outpatient if you’re getting emergency or observation services (which may include an overnight stay in the hospital or services in an outpatient clinic), lab tests or X-rays, without a formal inpatient admission, even if you spend the night in the hospital.
Does Medicare cover home health care? Yes, some home health is covered by Part A and/or Part B.
What does Original Medicare not cover? Original Medicare does not cover the majority of prescription drugs, routine dental care, or routine vision care.
Do I need Part D, and what happens if I don’t sign up? Part D helps cover prescription drugs, so if you take any prescription medications or want to be covered if you’re prescribed medications, having Part D can be a way to get help paying those costs. You may have to pay a late enrollment penalty if you enroll anytime after your Initial Enrollment Period is over and there’s a period of 63 days or more in a row when you don’t have Medicare drug coverage or other creditable prescription drug coverage. You’ll generally have to pay the penalty as part of your monthly premium for as long as you have Medicare drug coverage. If you get Extra Help, you don’t pay a late enrollment penalty.
What is Extra Help? Extra Help is a program to help individuals with limited income and resources pay some Medicare drug costs.
What’s Medigap, and do I need it? Medigap is additional insurance in addition to Original Medicare, that helps lower your portion of your medical costs. You don’t have to have Medigap. It’s an option to help cover the remaining costs you have after Medicare pays its portion.
What’s the difference between Medigap and Medicare Advantage? Medigap is additional insurance that helps pay your portion of your medical costs, while Medicare Advantage is an alternative insurance plan to Original Medicare.
Can I have Medigap and Medicare Advantage at the same time? No, you can’t.
Does Medigap cover prescription drugs? No, Medigap doesn’t cover prescription drugs.
When’s the best time to buy Medigap? The best time to buy Medigap is during your Medigap Open Enrollment Period.
What’s the Medigap Open Enrollment Period, and does it repeat? It’s the 6-month period that starts the first month you have Medicare Part B and you’re 65 or older. No, it doesn’t repeat. There are some states that do offer additional Medigap Open Enrollment Periods.
Does my state offer additional Medigap enrollment rules? Some states have additional Medigap enrollment rules, including California, Connecticut, Idaho, Illinois, Maine, Massachusetts, Nevada, New Mexico (starting in 2027), and New York.
Where can I find information about my specific state? You can find the information at the State Health Insurance Assistance Program (SHIP) website.
What is the State Health Insurance Assistance Program (SHIP)? SHIP is a free, federally funded program that provides local, in-depth, objective insurance counseling for Medicare-eligible individuals, their families, and caregivers. They do not sell insurance. It’s important to note that it’s not called SHIP in every state.
Can I be denied a Medigap policy? You can’t be denied a Medigap policy during Medigap Open Enrollment. However, if you miss the Medigap Open Enrollment Period, it is possible to be denied. There are some states that have exceptions. For more information on which states have exceptions, visit the State Health Insurance Assistance Program (SHIP) website.
Can I buy Medigap if I’m under 65? It’s possible to buy Medigap if you’re under 65, but it’s not guaranteed.
What’s the difference between the Medigap plan letters? Medigap plan letters stand for different Medigap plans, and each plan covers different amounts of your remaining cost after Medicare has paid its portion.
Why does the same plan letter cost different amounts at different companies? The same plans cost different amounts because private companies set their own prices.
Can I switch Medigap policies later? Yes, but it may result in higher costs for you.
Are Medigap plans different in Massachusetts, Minnesota, and Wisconsin? Yes, Medigap plans are different in Massachusetts, Minnesota, and Wisconsin.
What are guaranteed issue rights, and when do I have them? A guaranteed issue right is a situation when an insurance company can’t deny you a Medigap policy. A few examples are when your Medicare Advantage plan is leaving Medicare, your plan stops giving care in your area, or you move out of the plan’s service area.
What’s a trial right? A trial right is when you choose a Medicare Advantage Plan or Program of All-Inclusive Care for the Elderly (PACE) when you first become eligible for Medicare at 65 and you decide to switch to Original Medicare within the first year.
What is PACE? PACE is the Program of All-Inclusive Care for the Elderly. It’s a Medicare and Medicaid program offered in many states that allows people who otherwise would need a nursing home-level of care to remain in the community, like a home or apartment, for as long as possible.
What does PACE cover? PACE covers all Medicare- and Medicaid-covered care and services that the PACE team of health care professionals decides are necessary to improve and maintain your health and wellness.
How do you qualify for PACE? You qualify for PACE if you’re 55 or older, you live in the service area of a PACE organization, you’re certified by your state as needing a nursing home-level of care, and at the time you join, you’re able to live safely in the community with the help of PACE services.
Can I keep my Medigap policy if I get sick? Yes, you can keep your Medigap policy if you get sick, as long as you continue to pay your Medigap premiums.
What’s Medicare Part C (Medicare Advantage)? Medicare Part C (Medicare Advantage) is a Medicare-approved plan from a private company that is an alternative to Original Medicare for your health and drug coverage. Most of these plans bundle Parts A, B, and D together.
Sources
Medicare & You 2027. The official U.S. government Medicare handbook.
https://www.medicare.gov/coverage/durable-medical-equipment-dme-coverage
https://www.uscis.gov/save/resources/information-for-save-users-cuban-haitian-entrants
https://www.hopkinsmedicine.org/health/conditions-and-diseases/end-stage-renal-failure
https://www.humana.com/medicare/medicare-resources/observation-status
https://www.medicare.gov/health-drug-plans/part-d/basics/creditable-coverage
https://www.medicareresources.org/enrollment-options/#statevariation
https://www.shiphelp.org/what-we-do/about-ships/
https://www.medicareresources.org/glossary/service-area/
https://www.medicaidlongtermcare.org/eligibility/level-of-care/
Healthcare Uncomplicated provides general health system education only and does not offer medical, legal, or financial advice. Always consult a qualified professional for your specific situation.
Want to work with me? Book a free, 15-minute consult.
