What Is Medicare? Parts A, B, C & D Explained (2026)
Medicare comes in four parts, A, B, C, and D, and how you combine them decides what you pay and which doctors you can see.
BC
Brevy Care Team
10 min read · Published June 3, 2026 · Last verified July 9, 2026
Medicare comes in four parts, A, B, C, and D, and how you combine them decides what you pay and which doctors you can see. It's the federal health insurance program for people age 65 and older, plus some younger people with disabilities or specific conditions. This guide explains what each part covers, who qualifies, what it costs in 2026, when to sign up, and what Medicare does not pay for, so you can make the first decisions with confidence.
In this guide
Medicare runs on a few core choices, and the order they come in matters. You confirm you're eligible, decide between the two ways to receive benefits, sign up during the right window, and then handle the gaps Medicare leaves open. The sections below walk that path.
Who qualifies for Medicare
Medicare eligibility runs on age first, then on a few disability and medical paths for younger people.
You qualify at age 65 if you're a U.S. citizen or a lawful resident who has lived in the country for at least five years. Most people at 65 also qualify for premium-free Part A, because they or a spouse paid Medicare taxes for at least 40 quarters (10 years) of work.U.S. Government Publishing Office. (n.d.). 42 U.S.C. 426 - Entitlement to hospital insurance benefits. govinfo.gov. Retrieved Jun 22, 2026, from https://www.govinfo.gov/content/pkg/USCODE-2022-title42/html/USCODE-2022-title42-chap7-subchapII-sec426.htm
Disability. After you've received Social Security Disability Insurance (SSDI) for 24 months, you're enrolled automatically in Parts A and B; coverage starts in the 25th month.
ALS. A diagnosis of amyotrophic lateral sclerosis (Lou Gehrig's disease) waives the 24-month wait. Medicare starts the same month your SSDI benefits begin.
End-stage renal disease (ESRD). Permanent kidney failure requiring dialysis or a transplant qualifies you at any age. If ESRD is your only basis for Medicare, coverage usually starts in the fourth month of dialysis.
The four parts of Medicare
The single most useful thing to understand is what each part does. The official breakdown lives on the parts of Medicare page; here is the working version.
Part A is hospital insurance. It covers inpatient hospital stays, skilled nursing facility care after a hospital stay, hospice, and some home health care. Most people pay no premium for Part A. You do pay a deductible each benefit period before it starts covering an inpatient stay.
Part B is medical insurance. It covers doctor visits, outpatient care, lab tests, durable medical equipment, ambulance services, and most preventive care. Part B has a monthly premium and an annual deductible, after which you generally pay 20% of the Medicare-approved amount for most services.Centers for Medicare & Medicaid Services. (2026). 2026 Medicare Parts A & B Premiums and Deductibles. cms.gov. Retrieved Jun 22, 2026, from https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles
Part C is Medicare Advantage. This is not a separate benefit so much as a different way to receive Parts A and B. Private plans approved by Medicare bundle your hospital and medical coverage, almost always add drug coverage, and often include extras like routine dental or vision. In exchange, you use the plan's provider network and follow its rules.
Part D is prescription drug coverage. Private plans cover outpatient prescription drugs. You can add a standalone Part D plan to Original Medicare, or get drug coverage built into a Medicare Advantage plan.
The two ways to get Medicare
Every beneficiary picks one of two structures. This is the decision that shapes your costs, your provider access, and your paperwork for the year.
Original Medicare is the federal program directly. You get Parts A and B, you can see any provider in the country that accepts Medicare, and there's no network. Original Medicare has no annual out-of-pocket limit on its own, so most people add two things: a standalone Part D drug plan, and a Medigap (Medicare Supplement) policy that pays the deductibles and coinsurance Original Medicare leaves to you.
Medicare Advantage replaces that bundle with a single private plan. It covers everything Parts A and B cover, usually folds in Part D, and caps your in-network out-of-pocket spending. In 2026 that cap is federally limited to $9,250 for in-network services, and many plans set it lower. The tradeoff: you're limited to the plan's network, and many services require prior authorization. You cannot pair a Medigap policy with a Medicare Advantage plan.Centers for Medicare & Medicaid Services. (n.d.). Compare Original Medicare & Medicare Advantage - Medicare.gov. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/your-coverage-options/compare-original-medicare-medicare-advantage Which plans you can actually choose from depends on where you live, since Medicare Advantage and Part D plan availability is set by region; our guide to Medicare plans and coverage by state shows how it varies.
One point that surprises people: with either path, you still pay the Part B premium. Medicare Advantage doesn't replace Part B; it's an additional way to receive those benefits, so the Part B premium continues alongside any plan premium. For a fuller comparison, see the dedicated guide linked at the end.
What Medicare costs in 2026
The Centers for Medicare and Medicaid Services announced the 2026 figures on November 14, 2025. They apply from January 1 through December 31, 2026.
Cost
2026 amount
Notes
Part A premium
$0 for most people
$311/month with 30–39 work quarters; $565/month with fewer than 30
Part A inpatient deductible
$1,736 per benefit period
A new deductible can apply more than once in a year
Set by each private plan; national base premium is $38.99
A benefit period is the unit Part A uses. It begins the day you're admitted as an inpatient and ends after you've been out of a hospital or skilled nursing facility for 60 days in a row. Because a new benefit period can start later in the same year, the Part A deductible can apply more than once in twelve months.
Higher earners pay an income-related surcharge on top of the standard Part B and Part D premiums, called IRMAA. It's based on your tax return from two years earlier. In 2026, the surcharge starts above $109,000 in income for a single filer (or $218,000 for a couple) and rises in tiers; at the top tier the total Part B premium reaches $689.90 a month.U.S. Social Security Administration. (2025). SSA - POMS: HI 01101.020 - IRMAA Sliding Scale Tables - 12/02/2025. secure.ssa.gov. Retrieved Jun 24, 2026, from https://secure.ssa.gov/poms.nsf/lnx/0601101020
When to sign up
Timing is where Medicare costs people real money, because some penalties last for life.
Your Initial Enrollment Period is a seven-month window around your 65th birthday: the three months before the month you turn 65, that month, and the three months after. If you're already receiving Social Security, you're enrolled in Parts A and B automatically. Otherwise you sign up yourself through the Social Security Administration.Centers for Medicare & Medicaid Services. (n.d.). Open Enrollment. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/health-drug-plans/open-enrollment
If you miss that window without other creditable coverage, the late penalties are steep and ongoing:
Part B: your premium rises 10% for each full 12-month period you could have had Part B but didn't, and the penalty lasts as long as you have Part B.Centers for Medicare & Medicaid Services. (n.d.). Avoid late enrollment penalties. medicare.gov. Retrieved Jul 15, 2026, from https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties
Part D: 1% of the national base premium is added for each month you went without creditable drug coverage, for as long as you have Part D.Centers for Medicare & Medicaid Services. (n.d.). Avoid late enrollment penalties. medicare.gov. Retrieved Jul 15, 2026, from https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties
There's an important exception. If you're still working at 65 and have coverage through a current employer, you can usually delay Part B and Part D without penalty and sign up later through a Special Enrollment Period. The rules around employer coverage are specific, so confirm them before you delay anything.
What Medicare doesn't cover
Knowing the gaps matters as much as knowing the coverage, because the gaps are where families get surprised.
The largest gap is long-term custodial care. Medicare pays for skilled nursing only on a short-term, post-acute basis: up to 100 days per benefit period, and only after a qualifying three-day inpatient hospital stay, per the skilled nursing facility benefit. It does not pay for ongoing help with daily activities, the kind of care most people mean by "nursing home." For that, families rely on private pay, long-term care insurance, or Medicaid.Centers for Medicare & Medicaid Services. (n.d.). SNF Care Coverage. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/coverage/skilled-nursing-facility-care
Medicare also covers little routine dental, vision, and hearing care, and doesn't cover most care received outside the United States. Many Medicare Advantage plans add some dental and vision benefits, which is part of their appeal, but the scope varies widely by plan.
Help paying for Medicare
Several programs lower Medicare's costs for people with limited income and resources. They're underused, largely because no one tells eligible people they exist.
Medicare Savings Programs are run by state Medicaid agencies and can pay your Part B premium, and in some cases your deductibles and coinsurance. In 2026 the resource limits are $9,950 for an individual and $14,910 for a couple.U.S. Social Security Administration. (2026). SSA - POMS: HI 00815.023 - Medicare Savings Programs Income and Resource Limits - 02/26/2026. secure.ssa.gov. Retrieved Jun 22, 2026, from https://secure.ssa.gov/poms.nsf/lnx/0600815023 Because they're run state by state, the names and details differ, which our guide to Medicare Savings Programs by state breaks down.
Extra Help (the Part D Low-Income Subsidy) lowers prescription drug premiums, deductibles, and copays. Its resource limits are higher than the Medicare Savings Program limits, so people who don't qualify for one may still qualify for the other through the drug-cost help program.
Medigap doesn't depend on income. It caps the open-ended cost-sharing in Original Medicare. Your strongest opportunity to buy one is the six-month Medigap Open Enrollment Period that starts when you're both 65 and enrolled in Part B; during it, insurers must sell you any policy they offer regardless of your health.Centers for Medicare & Medicaid Services. (2025). Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare (CMS/NAIC, 2025) - Medicare.gov. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/publications/02110-medigap-guide-health-insurance.pdf
If you have both Medicare and Medicaid, the two programs coordinate, and special plans exist to integrate them. See the dual-eligible guide below.
Frequently Asked Questions
Is Medicare free?
No. Most people get Part A premium-free because of their work history, but Part B has a standard premium of $202.90 a month in 2026, and Parts A and B both have deductibles and coinsurance. Part C and Part D plans set their own premiums.Centers for Medicare & Medicaid Services. (2026). 2026 Medicare Parts A & B Premiums and Deductibles. cms.gov. Retrieved Jun 22, 2026, from https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles
Do I have to take Medicare at 65?
Not always. If you're still working and covered by a current employer's plan, you can usually delay Part B and Part D without a penalty and enroll later through a Special Enrollment Period. If you don't have qualifying coverage, delaying triggers lifelong late penalties, so check your situation before you wait.
What's the difference between Medicare and Medicaid?
Medicare is federal health insurance based mostly on age and work history. Medicaid is a joint federal-state program based on income and need. Many older adults qualify for both, which is called being "dual-eligible," and the two programs coordinate coverage.
Can I change my Medicare coverage later?
Yes. Each fall, the Medicare Open Enrollment Period (October 15 to December 7) lets you switch between Original Medicare and Medicare Advantage, change Part D plans, and adjust coverage for the coming year. Buying a Medigap policy later, however, may require medical underwriting once your one-time open enrollment window has passed.Centers for Medicare & Medicaid Services. (n.d.). Open Enrollment. medicare.gov. Retrieved Jun 23, 2026, from https://www.medicare.gov/health-drug-plans/open-enrollment
Find personalized help comparing your Medicare options and enrollment windows at brevy.com.
The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.
BC
Brevy Care Team
Expert eldercare guidance from Brevy's team of healthcare professionals and researchers.