Medicare Explained: Parts A, B, C and D
Medicare is health insurance for people 65 and older, and some younger people with disabilities, but it's made of several parts with different rules and costs. This guide covers what each part pays for, what you'll pay, Original Medicare vs Medicare Advantage, Medigap, how to enroll, working past 65, deadlines and help with costs.
By Pond.com editors Updated 5 min read
Quick answer
- Medicare is federal health insurance for people 65 and older and some younger people with disabilities.
- Part A covers hospital care, Part B covers doctors and outpatient care, and Part D covers prescription drugs.
- Part C, Medicare Advantage, is an alternative from private insurers that bundles A, B and usually D.
- Most people pay no premium for Part A but do pay a monthly premium for Part B.
- Signing up late can mean lifelong penalties, so know your enrollment window.
Medicare covers more than 65 million Americans, but its mix of parts, plans and deadlines confuses almost everyone at first. Understanding the basics before you turn 65 helps you avoid penalties and choose coverage that fits your health and budget.
This guide is general information, not medical, legal or financial advice. Medicare costs change every year; check Medicare.gov for current amounts.
Who qualifies
- People 65 and older who are US citizens or long-term legal residents
- Younger people who've received Social Security disability benefits for 24 months
- People with certain conditions, such as end-stage kidney disease or ALS
The four parts
| Part | What it covers | What you usually pay |
|---|---|---|
| A: Hospital insurance | Inpatient hospital stays, skilled nursing after a hospital stay, hospice, some home health care | Usually no premium; a deductible per hospital stay |
| B: Medical insurance | Doctor visits, outpatient care, tests, preventive care, medical equipment | A monthly premium, higher for high earners; a yearly deductible; usually 20% coinsurance |
| C: Medicare Advantage | Private plans that cover everything in A and B, usually D, and often extras | The Part B premium, plus any plan premium and copays |
| D: Prescription drugs | Outpatient prescription drugs, through private plans | A plan premium, deductible and copays, with a yearly cap on out-of-pocket drug costs ($2,100 in 2026) |
What Original Medicare costs in 2026
| Cost | 2026 amount |
|---|---|
| Part A premium | $0 for most people; up to $565 a month if you or your spouse didn't pay Medicare taxes long enough |
| Part A hospital deductible | $1,736 per benefit period |
| Part B standard premium | $202.90 a month, more for higher incomes |
| Part B deductible | $283 a year |
| Part B coinsurance | Usually 20% of the Medicare-approved amount, with no yearly cap |
Amounts change every January. Part D and Medicare Advantage costs depend on the plan you choose.
Original Medicare or Medicare Advantage?
This is the biggest choice you'll make.
- Original Medicare (A and B): use any doctor or hospital in the US that accepts Medicare, with no referrals. There's no yearly limit on what you pay, so most people add a Medigap policy and a Part D plan.
- Medicare Advantage (Part C): one private plan, often with low or no extra premium and extras like dental or vision. You usually use a network and may need referrals, but there's a yearly out-of-pocket limit.
| Original Medicare + Medigap + Part D | Medicare Advantage | |
|---|---|---|
| Doctors and hospitals | Any that accept Medicare, nationwide | Usually a local network |
| Referrals | Not needed | Often needed for specialists |
| Monthly cost | Higher: Part B, Medigap and Part D premiums | Lower: Part B plus a plan premium, often $0 |
| Costs when you get care | Low and predictable with Medigap | Copays that add up, up to a yearly limit |
| Extras like dental and vision | Not included | Often included |
| Prior approval for care | Rarely | More common |
Medigap (Medicare Supplement Insurance) is a private policy that pays some or all of the costs Original Medicare leaves you with, such as the 20% coinsurance. Your best time to buy it is the six months after you're 65 and enrolled in Part B, when insurers must sell you a policy whatever your health. Later, in many states, they can turn you down or charge more.
See Medicare Advantage vs Medigap for a detailed comparison.
Key deadlines
- Initial enrollment: a seven-month window around your 65th birthday: three months before, the month you turn 65 and three months after.
- Medicare open enrollment: October 15 to December 7 each year, to change Medicare Advantage or Part D plans for the next year.
- Late enrollment penalties for Parts B and D can last as long as you have coverage.
See when to sign up for Medicare.
How to enroll
- Automatically: if you already get Social Security or Railroad Retirement benefits, you're enrolled in Parts A and B when you turn 65. Your card arrives about three months before.
- Online or by phone: if not, sign up through Social Security at SSA.gov or by phone.
- Then choose: a Part D plan, or a Medicare Advantage plan, at Medicare.gov, and a Medigap policy directly from an insurer if you want one.
If you're still working at 65
If you or your spouse have health coverage through a current job at an employer with 20 or more employees, you can usually delay Part B without a penalty and sign up later during a special enrollment period. Many people still take premium-free Part A.
Be careful if you have an HSA: once any part of Medicare starts, you can't put more money into it. Coverage through COBRA or retiree plans doesn't count as current employment, so it won't protect you from the Part B late penalty.
Common mistakes to avoid
- Missing your initial enrollment window and paying penalties for life
- Assuming Medicare covers long-term care. It covers only short stays in a skilled nursing facility after a hospital stay. See long-term care options and costs.
- Choosing a plan on premium alone, without checking doctors and prescriptions
- Never reviewing your plan, even though plans change every year
Help with costs
If your income and savings are limited, you may qualify for:
- Medicare Savings Programs, which can help pay Part B premiums and other costs
- Extra Help, which lowers prescription drug costs
- Medicaid, for people who qualify for both
Common questions
Not entirely. Most people get Part A without a premium because they or a spouse paid Medicare taxes long enough. Part B has a monthly premium, set each year, and higher earners pay more. There are also deductibles, coinsurance and drug costs.
If you already get Social Security, you're usually enrolled in Parts A and B automatically. Otherwise you need to sign up. If you or your spouse still work and have coverage from a large employer, you may be able to delay Part B without a penalty. Check before you decide.
Original Medicare generally doesn't cover routine dental care, eyeglasses or hearing aids. Many Medicare Advantage plans include some of these benefits, or you can buy separate coverage.
Every state has a State Health Insurance Assistance Program (SHIP) offering free, unbiased Medicare counseling. You can also call 1-800-MEDICARE or use the plan finder at Medicare.gov.
People with higher incomes pay an extra charge, called IRMAA, on Part B and Part D premiums. It's based on your tax return from two years earlier. If your income has dropped because of a life-changing event, such as retirement, you can ask Social Security to review it.