Everything you need to know about Medicare, explained plainly.

What Medicare actually is

Medicare is the federal health insurance program for people 65 and over, and for some younger people with a disability, end-stage renal disease or ALS. The Centers for Medicare and Medicaid Services runs it, while Social Security handles most of the enrollment, which is why you apply in one place and are covered by another. It is not the same thing as Medicaid: Medicare turns mostly on age or disability, Medicaid is a joint federal and state program based on income, and a significant number of people qualify for both. Most workers pay Medicare taxes out of every paycheck, and those taxes fund the hospital side, which is why most people never pay a premium for Part A.

The four parts

Medicare is built from four parts, and each covers a different kind of care. Parts A and B together are what people call Original Medicare and come from the government. Parts C and D come from private insurers approved by Medicare.

• Part A, hospital insurance: Inpatient stays, skilled nursing after a qualifying hospital stay, hospice and some home health care. Usually no premium, but a $1,736 deductible per benefit period.
• Part B, medical insurance: Doctor visits, outpatient care, equipment and preventive care. $202.90 a month as the 2026 standard premium, a $283 annual deductible, then usually 20% coinsurance.
• Part C, Medicare Advantage: A private plan delivering your Part A and B benefits, usually with drugs included and often with dental, vision and hearing added.
• Part D, prescription drugs: Either a stand-alone plan or built into Medicare Advantage. Covered drug costs are capped at $2,100 a year, and insulin at $35 a month.

The one big decision: Original Medicare or Medicare Advantage

Almost everything else follows from this choice. Original Medicare lets you see any doctor or hospital in the country that accepts Medicare, usually without referrals, but it has no annual limit on what you can pay and does not cover most routine dental or long-term care, so people generally add a drug plan and a Medigap policy. A Medicare Advantage plan bundles hospital, medical and usually drug coverage into one plan, nearly always with a provider network and always with a yearly cap on your out-of-pocket costs. Costs, networks and extras vary by plan and by county, which is why two neighbors can get very different answers.

Filling the gaps with Medigap

Original Medicare leaves you with deductibles, copayments and coinsurance, and Medicare Supplement Insurance, usually called Medigap, exists to pay those. The plans are standardized and lettered, so Plan G from one insurer has the same core benefits as Plan G from another and price is the main difference between them. Two constraints matter: Medigap works only alongside Original Medicare and never with a Medicare Advantage plan, and it includes no drug coverage at all, so you add a Part D plan beside it.

What Medicare does not cover

Medicare covers a great deal, but the gaps are specific and they surprise people. The biggest by far is long-term care, the day-to-day help with bathing and dressing that most people assume is included and is not. Because that care is expensive and Medicare does not pay for it, it is worth planning for separately rather than discovering it later.

• Long-term care: Help with daily living at home or in a nursing home. Not covered.
• Most dental care and dentures: Some Medicare Advantage plans add limited cover.
• Routine eye exams and glasses: Same: an Advantage plan may include some.
• Hearing aids: Not covered by Original Medicare.

Who qualifies, and how you sign up

You are generally eligible at 65 as a U.S. citizen, or as a lawful resident of at least five years, and you may qualify sooner through disability. Whether you have to do anything depends entirely on one fact: if you already receive Social Security or Railroad Retirement benefits, you are enrolled automatically at 65 and a card arrives. If you are not collecting benefits yet, nobody enrolls you and you must sign up yourself, usually online with Social Security. Applying costs nothing, and anyone offering to file it for a fee should be declined.

Timing is the detail that costs the most

Your Initial Enrollment Period is a seven-month window around your 65th birthday: three months before, the month itself, three months after. Miss it without qualifying coverage from current work and you can pay a late enrollment penalty for as long as you hold Medicare, which for Part B and Part D usually means for life. If you are still working at 65 with coverage from a large employer you may be able to wait, and that is the main legitimate reason to. After you are enrolled, Open Enrollment each fall, October 15 to December 7, is when you change plans for the following January.

How Medicare works alongside other coverage

Most people arrive at Medicare already insured, and the rule that matters is which plan pays first. Coverage from a current job at a company with 20 or more employees usually pays first, with Medicare second. Retiree plans, COBRA and Marketplace coverage all work differently, and in most of those cases Medicare becomes your primary insurance whether or not you have enrolled, which is how gaps appear. Veterans can use VA care alongside Medicare, and military retirees with TRICARE For Life generally need both parts of Original Medicare to keep it. People with both Medicare and Medicaid, known as dual eligible, may have almost all costs covered and can choose plans built specifically for them. Before dropping any existing coverage, get in writing from that plan how it works with Medicare.

What it costs

What you actually pay depends on the choices above rather than on Medicare itself. Nearly everyone pays a monthly Part B premium, and most people add a drug plan premium and often a Medigap premium on top. Then come deductibles before coverage starts, and copayments or coinsurance when you receive care. Higher earners pay more for both medical and drug coverage through IRMAA, which is based on your tax return from two years earlier. If your income is limited, this is the part to check before choosing anything, because Medicare Savings Programs and Extra Help can reduce or eliminate several of those costs.

How to choose, in four questions

The decision is less about comparing plans than about knowing yourself. Do you want freedom to see any provider who accepts Medicare, or is a network acceptable? Would you rather pay more each month for predictable costs, or less each month and more when you need care? Which prescriptions do you take, and which pharmacy do you use? Do you travel, or live part of the year in another state? Answer those four and the path usually picks itself: Original Medicare with Medigap and a drug plan, or Medicare Advantage. Whichever you choose, review it each fall, because plans change their costs, networks and drug lists every single year.