The first time you read about Medicare, the letters can feel like alphabet soup. Part A, Part B, Part C, Part D, plus Medigap on top. The structure is actually simple once you see it. Parts A and B are Original Medicare. Part C is a different way to get A and B. Part D is drug coverage. Here is what each does.
Part A: hospital insurance
Medicare Part A generally helps pay for:
- Inpatient care in a hospital.
- Skilled nursing facility care after a qualifying hospital stay.
- Hospice care.
- Some home health care.
Most people do not pay a monthly premium for Part A if they or a spouse paid Medicare taxes for enough years. Part A does have a deductible for each benefit period and cost-sharing for longer stays.
Part B: medical insurance
Medicare Part B generally helps pay for:
- Doctor visits and specialist services.
- Outpatient care and many diagnostic tests.
- Preventive services such as screenings and vaccines.
- Durable medical equipment such as walkers.
Part B has a monthly premium, an annual deductible, and typically 20 percent coinsurance for many covered services. There is no cap on what you could pay in a year unless you have other coverage. Higher-income beneficiaries pay a higher Part B premium, known as an income-related adjustment.
Part C: Medicare Advantage
Part C is also called Medicare Advantage. Instead of Original Medicare, you get your Part A and Part B benefits through a private insurance company approved by Medicare. These plans:
- Must cover everything Original Medicare covers (with the exception of hospice, which Original Medicare still handles).
- Usually include prescription drug coverage.
- Often include extra benefits like dental, vision, hearing, or fitness memberships.
- Use networks such as HMOs or PPOs.
- Include an annual out-of-pocket maximum.
You still pay your Part B premium, and the plan may charge its own premium, which varies by plan.
Part D: prescription drug coverage
Part D plans are sold by private insurers and help pay for prescription drugs. You can add one to Original Medicare, or it may be built into a Medicare Advantage plan. Each Part D plan has its own formulary (drug list), pharmacy network, premium, deductible, and cost-sharing. If you do not join when first eligible and have no other creditable drug coverage, you may owe a lifetime late enrollment penalty. Read what Part D actually costs for how the pieces add up.
Where does Medigap fit?
Medicare Supplement (Medigap) is separate insurance that works alongside Original Medicare. It helps pay deductibles and coinsurance that Original Medicare leaves to you. You cannot use Medigap with a Medicare Advantage plan. People who choose Medigap generally also add a Part D plan.
Not sure which combination fits you?
We'll walk through your doctors, drugs, and budget and show you the real options.
Get my plan reviewThe two common ways to put it together
- Original Medicare + Medigap + Part D. Higher monthly premiums, broad doctor choice, and predictable costs when you use care.
- Medicare Advantage (Part C), usually with Part D built in. Often low premiums and extras, but you use a network and pay copays.
Neither is automatically better. See Advantage vs. Medigap for a closer comparison.
When do you enroll?
Your Initial Enrollment Period lasts seven months, around your 65th birthday. After that, there are specific windows each year. If you are approaching 65, see our Turning 65 guide. Delaying Part B or Part D without other qualifying coverage can lead to penalties, so timing matters.
Plain-English summary
- Part A: hospital.
- Part B: doctor and outpatient care.
- Part C: a private-plan alternative that bundles A, B, and usually D.
- Part D: prescription drugs.
- Medigap: optional add-on for Original Medicare.
Common beginner mistakes
- Assuming Medicare covers everything. It does not cover most long-term custodial care, routine dental, or routine vision.
- Missing the Part B window while still working. Whether you can delay depends on the size of your employer and the type of coverage, so ask before you decide.
- Skipping drug coverage because you take few medications today.
- Thinking Medigap and Advantage can be combined. They cannot.
- Ignoring the annual review. Plans change every year.
Questions worth asking before you enroll
Before choosing any combination, write down your answers to a few simple questions: Which doctors do I want to keep? Which medications do I take, and at what dose? Do I travel or live in more than one state? How comfortable am I with a bill I cannot predict? Your answers point toward Original Medicare with Medigap or toward an Advantage plan far more reliably than any ad will.
How we help
Honorbrook is an independent agency and we compare the real plans available at your address. Our help is free to you, because carriers pay us and your premium is the same either way. We can walk you through your options by phone.
Medicare help in your state
Honorbrook is licensed in the 11 states below. Plan availability, costs and some rules vary by state and county, so call us at (571) 354-0146 for what applies where you live.