Medicare Parts A, B, C, and D, Explained Simply

The whole map in one minute

Part A is hospital coverage. Part B is doctor and outpatient coverage. Part C, called Medicare Advantage, is a different way to get your A and B benefits through a private plan. Part D is prescription drug coverage. That's the entire alphabet. Everything else in Medicare is a detail hanging off one of those four.

One more label you'll see constantly: Part A and Part B together, run directly by the federal government, are called Original Medicare. Keep that name in mind, because the biggest decision in Medicare is whether to stay on Original Medicare or move to Part C. That fork gets its own section below.

Part A is the hospital part

Part A helps pay for inpatient hospital stays, some skilled nursing care after a hospital stay, hospice, and some home health care. The good news is the price. If you or your spouse worked and paid Medicare taxes for about ten years (the rule counts it as 40 quarters), you pay no monthly premium for Part A. Most people fall into that group. Source: CMS, 2026 Medicare Parts A & B Premiums and Deductibles fact sheet, 2026.

Part A isn't free once you actually use it, though. In 2026 the Part A deductible is $1,736, which is the amount you pay before Part A starts paying. That deductible applies per benefit period, not per year. A benefit period starts the day you're admitted and ends once you've gone 60 days in a row without inpatient hospital or skilled nursing care. Go back in after that, and a new benefit period starts, with a new $1,736 deductible. Two separate stays in one year can mean paying it twice. Source: CMS, 2026 Medicare Parts A & B fact sheet; Medicare.gov, inpatient hospital care, 2026.

Part B is the doctor and outpatient part

Part B covers doctor visits, preventive care, lab tests, outpatient procedures, and durable medical equipment like a walker. Most of the care that happens outside a hospital bed lives here. Unlike Part A, most people pay a monthly premium for Part B: the standard amount is $202.90 a month in 2026. There's also a yearly deductible of $283, and once you've met it, Medicare generally pays 80% of the approved cost and you pay the other 20%. The paperwork calls your share coinsurance; most people just call it the 20%. Source: CMS, 2026 Medicare Parts A & B Premiums and Deductibles fact sheet, 2026.

Part B also carries the single most expensive mistake in Medicare. If you don't sign up when you're first supposed to, and you don't have health coverage from a job you or your spouse still actively works at, your premium can go up 10% for every full 12 months you waited, and you keep paying that penalty for as long as you have Part B. Source: Medicare.gov, Part B late enrollment penalty, 2026. Your first chance to sign up is a 7-month window: the three months before your 65th birthday month, your birthday month, and the three months after. One piece of fine print: if your birthday falls on the first of a month, the whole window shifts one month earlier. Source: Medicare & You 2026 handbook, CMS. Our guide on when to sign up for Medicare walks through that window date by date, including what changes if you're still working at 65.

The fork: Original Medicare or Medicare Advantage

Once you have A and B, you reach the one real decision, and it's the spot that confuses people most. You have two roads.

Road one is Original Medicare. You can see any provider in the country who accepts Medicare, and no referrals are needed. But Original Medicare puts no yearly cap on what that 20% can add up to, so many people add two things: a Medigap policy, which is private insurance that fills the gaps (people often call it a supplement or a gap plan), and a separate Part D drug plan. Medigap plans are standardized by letter, A through N, so a Plan G from one company covers the same core benefits as a Plan G from another; companies compete mostly on price and service. Plan G and Plan N are two of those letters, and our Plan G vs Plan N guide compares them side by side. Plan F is closed to anyone who became eligible on or after January 1, 2020. Massachusetts, Minnesota, and Wisconsin standardize Medigap their own way. Source: Medicare.gov, Medigap basics, 2026.

Road two is Part C, Medicare Advantage. It's a private plan the government pays to deliver your Part A and Part B benefits, usually with drug coverage built in and often with extras like some dental, vision, or hearing. It works more like the insurance many people had at work: a network of doctors, sometimes referrals, its own copays (the flat amounts you pay at a visit), and a yearly out-of-pocket maximum, meaning a ceiling on what you pay for covered care each year. Some of these plans charge no monthly premium beyond your Part B premium, which sounds attractive, and the trade is the network and the plan's rules. The extras vary a lot by plan and location, and they're usually capped. Source: Medicare.gov, your coverage options, 2026.

Neither road is the right answer for everyone. Our guide to Medicare Advantage vs Medigap lays out the real tradeoffs side by side.

Part D is the drug part

Part D is prescription drug coverage. On the Original Medicare road, you buy it as a standalone plan. On the Advantage road, it's usually built in. Every Part D plan has its own premium and its own formulary, which is the plan's list of covered drugs, and that list is different from plan to plan. That's why the right drug plan depends entirely on the specific medications you take.

The headline 2026 number is genuinely good news. Part D now has a yearly cap on what you pay out of pocket for covered drugs: $2,100 in 2026, up from $2,000 in 2025. Once your out-of-pocket costs reach $2,100, you pay nothing more for covered drugs for the rest of the year. One detail keeps that honest: the cap counts what comes out of your pocket, not the sticker price of the drugs. Source: CMS, Final CY2026 Part D Redesign Program Instructions; Medicare.gov, costs for Medicare drug coverage, 2026. Exactly which payments count toward the cap, and which ones sit outside it, is spelled out in our 2026 Medicare costs guide.

Part D is voluntary, and nobody makes you enroll. But if you go 63 or more days in a row without Part D or other creditable drug coverage (coverage expected to pay, on average, at least as much as Medicare's standard drug coverage) after your first chance to sign up ends, Medicare adds a late enrollment penalty when you do join, and you generally keep paying it for as long as you have Medicare drug coverage. Source: Medicare.gov, Part D late enrollment penalty, 2026. If you're healthy and tempted to wait, read our guide on whether you need Part D if you take no prescriptions before you decide.

The calendar dates people mix up

Medicare has several enrollment windows, and they're easy to confuse. Three matter most:

• 7 months Your first sign-up window, around your 65th birthday: the 3 months before your birthday month, your birthday month, and the 3 months after.
• Oct 15 to Dec 7 The Annual Enrollment Period, every fall. People on Medicare can join, switch, or drop an Advantage or Part D plan; changes take effect January 1.
• Jan 1 to Mar 31 The Medicare Advantage Open Enrollment Period. Only for people already in an Advantage plan, and it allows one change. You can't use it to move from Original Medicare into Advantage.

Source: Medicare.gov, joining a health or drug plan, 2026.

The classic mix-up is thinking the fall window is when you first sign up for Medicare. It isn't. Your first sign-up is the 7-month window around 65. The fall window is for changing Advantage or Part D coverage from year to year, and our AEP game plan walks that season through date by date.

Questions people ask

Is Medicare Advantage the same thing as Part C?

Yes. Part C and Medicare Advantage are two names for the same thing: a private plan that delivers your Part A and Part B benefits, usually with drug coverage included. When an ad says Medicare Advantage, it's talking about Part C.

Is Part A really free?

Most people pay no monthly premium for Part A, thanks to those 40 quarters of Medicare taxes. But using it isn't free: the $1,736 deductible applies per benefit period, and long hospital stays add daily charges on top. Source: CMS, 2026 Medicare Parts A & B Premiums and Deductibles fact sheet, 2026. Our 2026 Medicare costs guide has every number, including the daily rates, in one table.

Do higher incomes pay more for Medicare?

Yes. It's called IRMAA, short for income-related monthly adjustment amount: a surcharge added to your Part B and Part D premiums. In 2026 it starts once income goes above $109,000 for a single filer or $218,000 on a joint return, and it's based on your tax return from two years ago, so your 2026 premium looks at 2024 income. The brackets are cliffs: one dollar over a line triggers the full next-bracket surcharge. Source: CMS, 2026 Medicare Parts A & B Premiums and Deductibles fact sheet, 2026.

Does Medicare cover long-term nursing home care?

Generally no, and it surprises a lot of families. Medicare covers short-term skilled care, like rehab in a skilled nursing facility after a qualifying hospital stay. It doesn't pay for ongoing custodial care, meaning day-to-day help with things like bathing and dressing. That kind of long-term care usually gets paid another way, such as Medicaid for people who qualify, or long-term care insurance. Source: Medicare.gov, long-term care, 2026.

You don't have to memorize any of this, and you don't have to decide anything from a headline or a TV ad. Know which part your question is about, then take the actual decision to the free official help below. Medicare.gov shows the real plans in your zip code, 1-800-MEDICARE (1-800-633-4227) answers questions day or night, and a counselor at your state's SHIP (the State Health Insurance Assistance Program) will talk it through with you one on one, with nothing to sell.