Medicare has four main parts, but you do not usually use all four in the same way.
Part A helps cover hospital and certain inpatient-related care. Part B helps cover doctor services, outpatient care, preventive services, and medical equipment. Part C, also called Medicare Advantage, is a private-plan alternative to Original Medicare. Part D helps cover prescription drugs.
The catch is that Medicare is not one single card that covers everything for free. You still need to choose how you get coverage, watch enrollment windows, compare drug plans or Medicare Advantage plans, and understand what is not covered.
In this article, Medicare means the U.S. federal Medicare program.
Start with the Medicare map
There are two main ways to get Medicare coverage.
The first way is Original Medicare. Original Medicare includes Part A and Part B. If you want prescription drug coverage with Original Medicare, you can usually add a separate Part D drug plan. You may also choose to buy Medicare Supplement Insurance, known as Medigap, to help pay some out-of-pocket costs that Original Medicare does not pay. Medicare.gov says Original Medicare includes Part A and Part B, lets you join a separate Part D plan, and lets you use any doctor or hospital that takes Medicare anywhere in the U.S.
The second way is Medicare Advantage, also called Part C. Medicare Advantage plans are private health plans approved by Medicare. These bundled plans include Part A and Part B and usually include Part D drug coverage. They may use provider networks, may require prior approval for certain services, and usually have different out-of-pocket costs from Original Medicare.
| Coverage path | What it usually includes | What you may add | Main catch |
|---|---|---|---|
| Original Medicare | Part A and Part B | Part D and Medigap | No built-in yearly out-of-pocket limit unless you have supplemental coverage |
| Medicare Advantage | Part A, Part B, and usually Part D | Extra benefits may be included by the plan | Networks, prior authorization, and plan rules matter |
This is the first decision.
Do you want Original Medicare with separate pieces, or a Medicare Advantage plan that bundles coverage into one private plan?
The four parts at a glance
| Medicare part | Common name | Main job | How you usually get it |
|---|---|---|---|
| Part A | Hospital Insurance | Helps cover inpatient hospital care, skilled nursing facility care, hospice, and some home health care | Through Original Medicare or inside Medicare Advantage |
| Part B | Medical Insurance | Helps cover medically necessary services, preventive services, doctors, outpatient care, and medical equipment | Through Original Medicare or inside Medicare Advantage |
| Part C | Medicare Advantage | A private-plan way to receive Part A and Part B, usually with Part D included | Through a Medicare-approved private plan |
| Part D | Prescription Drug Coverage | Helps pay for covered brand-name and generic prescription drugs | Separate drug plan with Original Medicare or included in many Medicare Advantage plans |
The letters make Medicare feel more complicated than it is.
The harder part is not remembering A, B, C, and D. The harder part is choosing the combination that fits your doctors, prescriptions, budget, travel, and comfort with plan rules.
Part A: hospital insurance
Medicare Part A is hospital insurance.
In general, Part A helps pay for inpatient care in hospitals, critical access hospitals, and skilled nursing facilities. It also helps cover hospice care and some home health care.
Part A is the piece people often think of first because hospital bills are scary. But Part A is not a blank check for every stay, facility, or long-term care need.
Part A may help cover:
- Inpatient hospital care
- Critical access hospital care
- Skilled nursing facility care after a qualifying hospital stay
- Hospice care
- Some home health care
The phrase “helps cover” matters.
You may still have deductibles, copayments, benefit period rules, and coverage limits.
What Part A costs in 2026
Most people do not pay a monthly premium for Part A because they or a spouse paid Medicare taxes long enough while working, usually at least 10 years. If you do not qualify for premium-free Part A, you may be able to buy it, and in 2026 the monthly premium is either $311 or $565 depending on how long you or your spouse worked and paid Medicare taxes.
Part A has a hospital deductible that works by benefit period, not simply by calendar year. In 2026, the Part A deductible is $1,736 for each time you are admitted to the hospital per benefit period before Original Medicare starts to pay. Medicare.gov also says there is no limit to the number of benefit periods you can have.
| Part A cost item | 2026 amount |
|---|---|
| Part A premium for most people | $0 |
| Part A premium if bought | $311 or $565 per month |
| Part A hospital deductible | $1,736 per benefit period |
| Inpatient hospital days 1 to 60 | $0 after deductible |
| Inpatient hospital days 61 to 90 | $434 per day |
| Lifetime reserve days 91 to 150 | $868 per day |
| After day 150 | You pay all costs |
The benefit period rule is one reason Medicare hospital costs can surprise people.
It is not the same as a regular health plan deductible that resets once per year.
Part B: medical insurance
Medicare Part B is medical insurance.
Part B helps cover medically necessary services and preventive services. Medicare.gov defines medically necessary services as services or supplies that meet accepted standards of medical practice to diagnose or treat a medical condition. Preventive services are meant to prevent illness or detect it early when treatment is likely to work best.
Part B commonly covers things like:
- Doctor visits
- Outpatient care
- Preventive services
- Ambulance services
- Clinical research
- Durable medical equipment
- Limited outpatient prescription drugs
- Mental health and substance use disorder services
Part B is the part that handles much of the routine medical system: doctor offices, outpatient tests, equipment, and preventive care.
But it is not free.
What Part B costs in 2026
In 2026, the standard Part B premium is $202.90 per month, or higher depending on income. You pay the Part B premium each month even if you do not use Part B services.
The 2026 Part B deductible is $283. After you pay the deductible, you usually pay 20% of the cost for each Medicare-covered service or item, as long as the provider accepts the Medicare-approved amount as full payment.
| Part B cost item | 2026 amount |
|---|---|
| Standard monthly premium | $202.90 |
| Annual deductible | $283 |
| Typical coinsurance after deductible | 20% of the Medicare-approved amount |
That 20% number is the reason many people look at Medigap or Medicare Advantage.
If a covered outpatient procedure has a Medicare-approved amount of $5,000 and you owe 20%, your share could be $1,000 after the deductible rules apply. For someone on a fixed income, that is not a small bill.
Why Part A and Part B together are called Original Medicare
Original Medicare is the traditional Medicare setup.
It includes Part A and Part B. It does not automatically include most outpatient prescription drug coverage. It also does not include a built-in yearly limit on what you pay out of pocket unless you have supplemental coverage like Medigap, Medicaid, employer or retiree coverage, or you join a Medicare Advantage plan. Medicare.gov states that Original Medicare has no yearly out-of-pocket limit unless you have supplemental coverage or join Medicare Advantage.
This is a big catch.
Original Medicare gives broad provider flexibility, but the cost exposure can be open-ended without something else attached.
Original Medicare may fit if:
- You want broad access to doctors and hospitals that accept Medicare.
- You travel often inside the U.S.
- You do not want a plan network controlling most non-emergency care.
- You are willing to add Part D and possibly Medigap.
- You can manage multiple pieces of coverage.
Original Medicare may feel incomplete if:
- You want prescription drug coverage but forget to add Part D.
- You want dental, vision, or hearing benefits included.
- You need a clear yearly out-of-pocket cap without buying supplemental coverage.
- You prefer one bundled plan with a network and plan-managed benefits.
Original Medicare is flexible.
It is also not finished until you decide what to do about drug coverage and out-of-pocket risk.
Part C: Medicare Advantage
Medicare Part C is Medicare Advantage.
Medicare Advantage is not a separate benefit that sits beside Part A and Part B. It is an alternative way to get your Medicare coverage through a private health plan approved by Medicare. Medicare.gov says Medicare Advantage plans include Part A, Part B, and usually Part D.
You still need Part A and Part B to join a Medicare Advantage plan. Medicare.gov says you need both Part A and Part B to join a Medicare Advantage plan, with or without drug coverage.
Medicare Advantage may include:
- Hospital coverage
- Medical coverage
- Prescription drug coverage in most plans
- Provider networks
- Prior authorization for some services
- A yearly out-of-pocket limit for covered Medicare services
- Extra benefits that Original Medicare does not cover, depending on the plan
Medicare Advantage plans must cover all medically necessary services that Original Medicare covers. Plans may also offer extra benefits that Original Medicare does not cover. Medicare.gov lists examples such as vision, hearing, dental, and more.
That sounds attractive.
The trade-off is that Medicare Advantage plans can have networks, service areas, prior authorization rules, and plan-specific cost sharing. Medicare.gov says you may need to use doctors and providers in the plan’s network and service area for non-emergency care, and some plans offer out-of-network non-emergency coverage at a higher cost.
What Medicare Advantage costs
Medicare Advantage costs vary by plan.
Some plans have a $0 plan premium, but that does not mean Medicare is free. Medicare.gov says you must have Part B and keep paying your Part B premium to stay in a Medicare Advantage plan. Deductibles, coinsurance, copayments, and out-of-pocket limits vary by plan.
| Medicare Advantage cost item | What to check |
|---|---|
| Part B premium | You usually keep paying it |
| Plan premium | May be $0 or more, depending on the plan |
| Deductible | Varies by plan |
| Doctor copays | Varies by plan and provider type |
| Hospital costs | Varies by plan |
| Prescription drug costs | Varies by plan formulary and pharmacy |
| Out-of-pocket limit | Varies by plan |
Medicare Advantage can be a good fit when the network, drug coverage, doctors, hospitals, and out-of-pocket limit work well for you.
It can be a poor fit if your favorite doctors are out of network, your prescriptions cost more, you travel often, or you dislike prior authorization rules.
Part D: prescription drug coverage
Medicare Part D helps cover prescription drugs.
You can usually get Part D in one of two ways: a separate Medicare drug plan if you have Original Medicare, or drug coverage built into many Medicare Advantage plans. Medicare.gov says you need either Part A or Part B to join a separate Medicare drug plan, while Medicare Advantage drug plans bundle Part A, Part B, and usually Part D through one plan.
Part D is easy to underestimate if you do not take medications now.
But skipping drug coverage can create a late enrollment penalty later if you go too long without Medicare drug coverage or other creditable prescription drug coverage. Medicare.gov says the Part D late enrollment penalty may apply if you go 63 days or more in a row without Medicare drug coverage or other creditable prescription drug coverage after you are eligible.
Part D plan details to check
- Monthly premium
- Deductible
- Drug formulary
- Drug tiers
- Preferred pharmacy network
- Mail-order options
- Prior authorization
- Step therapy
- Quantity limits
- Estimated yearly drug cost
Do not choose a Part D plan by premium only.
A low-premium plan can be expensive if your regular medication sits on a high tier or is not covered well.
What Part D costs in 2026
Part D premiums vary by plan. Your deductible, copayments, and coinsurance also vary by plan and pharmacy. Medicare.gov says no Medicare drug plan may have a deductible higher than $615 in 2026, and some plans have no deductible.
In 2026, after reaching the deductible if the plan has one, you generally pay 25% of the cost as coinsurance for covered generic and brand-name drugs until your out-of-pocket spending on covered Part D drugs reaches $2,100. After that, catastrophic coverage begins, and you pay nothing out of pocket for covered Part D drugs for the rest of the calendar year.
| Part D cost item | 2026 rule or amount |
|---|---|
| Premium | Varies by plan |
| Maximum deductible | $615 |
| Initial coverage coinsurance | Generally 25% after deductible |
| Out-of-pocket drug threshold | $2,100 for covered Part D drugs |
| After reaching catastrophic coverage | $0 out of pocket for covered Part D drugs for the rest of the year |
The $2,100 cap for covered Part D drugs is helpful.
But “covered” is doing work. You still need to check whether your drug is on the plan’s formulary, whether your pharmacy is preferred, and whether the plan requires prior authorization or step therapy.
Part D late enrollment penalty
The Part D late enrollment penalty is not a one-time slap on the wrist.
Medicare.gov says the Part D late enrollment penalty is permanently added to your Medicare drug coverage premium if it applies, and you generally pay it for as long as you have Medicare drug coverage. In 2026, the penalty is calculated by multiplying 1% of the national base beneficiary premium, which is $38.99, by the number of full uncovered months you were eligible for Medicare drug coverage but did not have Part D or other creditable drug coverage.
Simple penalty example
| Penalty item | Example |
|---|---|
| Uncovered months | 20 months |
| Penalty rate | 1% per uncovered month |
| 2026 national base beneficiary premium | $38.99 |
| Rough monthly penalty before rounding | $7.80 |
That may not sound huge.
But if it is added every month for as long as you have Part D coverage, it becomes annoying money. Worse, the penalty can change because the national base beneficiary premium can change each year.
What Medicare does not usually cover
Medicare does not cover everything.
Original Medicare does not cover some common needs, including eye exams for prescription glasses, long-term care, cosmetic surgery, massage therapy, routine physical exams, hearing aids and exams for fitting them, concierge care, and most dental care. Medicare.gov notes that Medicare Advantage plans may cover some extra benefits Original Medicare does not cover, such as certain vision, hearing, and dental services.
| Need | Original Medicare coverage pattern | What to check |
|---|---|---|
| Routine dental care | Usually not covered | Medicare Advantage, standalone dental, or self-pay |
| Hearing aids | Usually not covered | Medicare Advantage benefits or separate coverage |
| Routine vision | Usually not covered | Medicare Advantage benefits or separate coverage |
| Long-term custodial care | Usually not covered | Long-term care planning, Medicaid rules, personal savings |
| Foreign travel care | Usually limited | Some Medigap policies or travel coverage |
This is where many people get disappointed.
Medicare is valuable coverage. It is not complete coverage for every health-related cost.
Where Medigap fits
Medigap is not Part A, Part B, Part C, or Part D.
It is Medicare Supplement Insurance that can help cover your share of costs for services covered by Original Medicare, such as copayments, coinsurance, and deductibles. Medicare.gov says Medigap plans help cover out-of-pocket costs associated with Original Medicare, but generally do not cover long-term care, vision or dental care, hearing aids, glasses, or private-duty nursing.
Medigap only works with Original Medicare.
You cannot use Medigap to pay Medicare Advantage out-of-pocket costs. Medicare.gov says if you are in Medicare Advantage, you cannot buy Medigap to cover those out-of-pocket costs.
Original Medicare with Medigap may appeal if:
- You want broad provider access.
- You want help with the 20% Part B coinsurance.
- You travel within the U.S. and want fewer network issues.
- You are comfortable buying separate Part D coverage.
- You can afford the Medigap premium.
Medigap may not solve:
- Prescription drug coverage after 2005 policies
- Most routine dental care
- Most routine vision care
- Hearing aids
- Long-term care
Medigap can reduce Original Medicare cost risk.
It does not turn Medicare into unlimited coverage.
How enrollment timing works
Medicare timing matters because late enrollment can create gaps and penalties.
Your first chance to sign up for Medicare is usually around age 65. Medicare.gov says the Initial Enrollment Period generally lasts seven months: it starts three months before the month you turn 65 and ends three months after the month you turn 65.
If you miss your Initial Enrollment Period, you may have to wait to sign up and may pay a monthly late enrollment penalty for as long as you have Part B, unless you qualify for a Special Enrollment Period. Medicare.gov says the General Enrollment Period runs January 1 through March 31 each year, with coverage starting the month after you sign up.
| Enrollment period | Timing | What it affects |
|---|---|---|
| Initial Enrollment Period | Seven months around first Medicare eligibility | First chance to sign up for Medicare |
| General Enrollment Period | January 1 to March 31 | For people who missed certain earlier sign-up windows |
| Medicare Open Enrollment | October 15 to December 7 | Change Medicare Advantage or Part D choices for January 1 |
| Medicare Advantage Open Enrollment | January 1 to March 31 for people already in Medicare Advantage | Switch Medicare Advantage plans or return to Original Medicare |
Do not confuse Medicare Open Enrollment with Marketplace Open Enrollment.
They are different systems.
When you can change Medicare Advantage or Part D plans
Medicare Open Enrollment runs October 15 through December 7 each year. During that window, you can join, drop, or switch Medicare Advantage plans, join, drop, or switch Medicare drug plans if you are in Original Medicare, or switch between Original Medicare and Medicare Advantage. Changes made during this period are effective January 1 of the next year if the plan gets your enrollment request by December 7.
If you are already in a Medicare Advantage plan, the Medicare Advantage Open Enrollment Period runs January 1 through March 31. During that time, you can switch to another Medicare Advantage plan or drop Medicare Advantage and return to Original Medicare, with the option to join a separate Part D plan.
This is not just administrative detail.
If your doctor leaves the network, your drug moves to a worse tier, or your plan changes costs, the enrollment window determines when you can fix it.
Original Medicare vs Medicare Advantage: the practical trade-off
Original Medicare and Medicare Advantage can both be legitimate choices.
The better one depends on how you use care.
| Question | Original Medicare | Medicare Advantage |
|---|---|---|
| Can you use any doctor who accepts Medicare? | Generally yes | Often network-based for non-emergency care |
| Is Part D included automatically? | No, usually add separate Part D | Usually included in many plans |
| Is there a built-in yearly out-of-pocket limit? | No, unless you have supplemental coverage | Yes, plans have limits for covered Medicare services |
| Can you buy Medigap? | Yes | No, not to cover Medicare Advantage out-of-pocket costs |
| Can plans require prior authorization? | Usually not for Original Medicare services | May require approval for certain services or supplies |
| Can extra dental, vision, or hearing benefits be included? | Usually not | Often possible, depending on plan |
Medicare.gov says Original Medicare generally lets you use any doctor or hospital that takes Medicare, while Medicare Advantage may require network use for non-emergency care. It also says Original Medicare has no yearly out-of-pocket limit unless you have supplemental coverage, while Medicare Advantage plans have yearly limits for covered Medicare services.
This is the real trade.
Original Medicare gives flexibility. Medicare Advantage gives a bundled plan with a cap, but usually more plan rules.
How to choose the right Medicare setup
Start with your care, not the advertisement.
Medicare commercials often focus on extra benefits, low premiums, or simple plan names. Those details matter, but they are not the whole decision. You need to check doctors, hospitals, prescriptions, pharmacies, travel, chronic conditions, likely surgeries, and comfort with network rules.
Check these before choosing:
- Do your doctors accept Original Medicare?
- Are your doctors in the Medicare Advantage plan network?
- Is your preferred hospital in network?
- Are your prescriptions covered?
- Which pharmacies are preferred?
- What is the estimated yearly drug cost?
- Does the plan require prior authorization?
- What is the out-of-pocket maximum?
- Can you afford Medigap if choosing Original Medicare?
- Do you travel often or live in more than one area during the year?
Medicare.gov tells people joining health or drug plans to compare plans in their area, enter the prescriptions they take to estimate monthly and yearly costs, ask doctors and pharmacies about plan networks, review premiums and deductibles, and talk to other insurance providers before changing coverage if they have other insurance.
That is the checklist.
Not the TV ad. Not the mailer. Not the neighbor’s plan.
A simple example
Imagine Rosa is turning 65.
She sees a primary care doctor twice a year, takes two generic medications, travels to see family in another state, and wants broad doctor access. She is comfortable paying a monthly Medigap premium if it reduces surprise bills.
Original Medicare plus a Part D plan and Medigap may be worth comparing.
Now imagine Mike.
Mike rarely travels, his doctors are all in one local health system, he likes having one plan card, and he wants dental and vision benefits if the plan offers them. He is comfortable checking the network before care and handling plan rules.
A Medicare Advantage plan may be worth comparing.
| Person | Care pattern | Coverage path to compare first |
|---|---|---|
| Rosa | Travels, wants broad provider access, comfortable with separate pieces | Original Medicare, Part D, and Medigap |
| Mike | Local care, doctors in one system, wants bundled plan features | Medicare Advantage with drug coverage |
Neither person is automatically right.
They are just solving different problems.
Common Medicare mistakes
Thinking Part A and Part B cover everything
Original Medicare does not cover everything. Routine dental, routine vision, hearing aids, and long-term care are common gaps.
Forgetting Part D
If you choose Original Medicare and want drug coverage, you usually need a separate Part D plan. Waiting too long without creditable drug coverage can create a late enrollment penalty.
Choosing Medicare Advantage without checking doctors
Medicare Advantage plans may use networks and service areas for non-emergency care. A plan is not useful if it misses the doctors or hospitals you actually use.
Assuming a $0 premium plan has no costs
Some Medicare Advantage plans may have a $0 plan premium, but you generally still pay the Part B premium, and plan deductibles, copays, coinsurance, and out-of-pocket limits vary.
Ignoring the Part B premium
The standard Part B premium in 2026 is $202.90 per month, or higher depending on income. That cost still matters even if your Medicare Advantage plan has a low or $0 plan premium.
Confusing Medigap with Medicare Advantage
Medigap helps pay some Original Medicare out-of-pocket costs. It does not cover Medicare Advantage cost sharing.
Medicare parts worksheet
| Question | Your answer |
|---|---|
| Do you have Part A? | Yes / No / Not sure |
| Do you have Part B? | Yes / No / Not sure |
| Are you choosing Original Medicare or Medicare Advantage? | Original / Advantage / Not sure |
| If Original Medicare, do you have a Part D plan? | Yes / No / Not sure |
| If Original Medicare, are you comparing Medigap? | Yes / No / Not sure |
| If Medicare Advantage, are your doctors in network? | Yes / No / Not sure |
| Are your prescriptions covered? | Yes / No / Not sure |
| What is your monthly Part B premium? | $__________ |
| What is your plan premium, if any? | $__________ |
| What is your estimated yearly drug cost? | $__________ |
| What is your out-of-pocket risk? | $__________ |
| When is your next enrollment window? | __________ |
The “not sure” answers are the ones to fix before choosing coverage.
What I would check first
If I were sorting out Medicare, I would first decide whether I want Original Medicare or Medicare Advantage.
Then I would check prescriptions.
Drug costs can change the whole decision. A plan with a low premium can lose quickly if it handles your medication badly. A Medicare Advantage plan can look attractive until your specialist is out of network. Original Medicare can look simple until you realize there is no built-in yearly out-of-pocket cap without extra coverage.
After that, I would check timing.
Medicare decisions are not only about benefits. They are about enrollment windows, penalties, effective dates, and whether your current coverage works with Medicare.
Final thoughts
Medicare Parts A, B, C, and D are easier to understand once you stop treating them as four equal pieces.
Part A is hospital insurance. Part B is medical insurance. Together, they make up Original Medicare. Part C, or Medicare Advantage, is a private-plan alternative for getting Part A and Part B benefits, usually with drug coverage included. Part D is prescription drug coverage, either as a separate plan with Original Medicare or bundled into many Medicare Advantage plans.
The main money question is not just, “Which part covers what?”
It is, “Which combination gives me the doctors, drugs, costs, and rules I can live with?”
Compare Original Medicare with Medicare Advantage. Check whether you need Part D. Look at Medigap if you choose Original Medicare. Check networks and drug formularies if you choose Medicare Advantage. Watch enrollment windows and late penalties. Keep the 2026 costs in view, especially the Part B premium, Part A deductible, Part B deductible, and Part D drug cost rules.
Medicare is valuable coverage.
It still needs a plan.