Medicare is the federal health insurance program that primarily helps Americans aged 65 and older, but it also covers younger people with certain disabilities and specific medical conditions. As of late 2025, roughly 69.7 million people are enrolled in Medicare, with about 90% qualifying based on age and the remaining 10% qualifying through disability or chronic illness.
Adults 65 and Older
The largest group Medicare serves is people who have turned 65. If you’ve worked and paid Medicare taxes for at least 10 years (40 quarters of coverage), you qualify for premium-free Part A, which covers hospital stays, skilled nursing care, hospice, and some home health services. Most people in this group are already receiving Social Security benefits, which means they’re automatically enrolled in both Part A and Part B when they turn 65.
You don’t need to be a U.S. citizen by birth. Legal permanent residents (green card holders) who are 65 or older can also enroll, though they must have lived continuously in the United States for at least five years before applying. If you haven’t earned enough work credits for premium-free Part A, you can still buy into the program by paying a monthly premium, as long as you meet the age and residency requirements.
People With Disabilities Under 65
You don’t have to wait until 65 if you have a qualifying disability. Anyone receiving Social Security disability benefits automatically gets Medicare after 24 months of receiving those benefits. That two-year waiting period is a significant gap for many people, and it’s one of the most common frustrations with the system. During that time, you’d need to rely on other coverage like Medicaid, employer insurance, or marketplace plans.
There is one major exception to the waiting period: people diagnosed with ALS (Lou Gehrig’s disease) receive Medicare automatically as soon as their disability benefits begin, with no 24-month wait.
People With End-Stage Renal Disease
Medicare covers people of any age who have permanent kidney failure requiring dialysis or a kidney transplant. The timeline for when coverage starts depends on your treatment.
- Dialysis patients: Coverage typically begins on the first day of the fourth month of dialysis treatments. So if you start dialysis in July, Medicare kicks in October 1. You can shorten this waiting period to as early as the first month if you enroll in a home dialysis training program at a Medicare-certified facility.
- Kidney transplant patients: Coverage can begin the same month you’re admitted to a Medicare-certified hospital for your transplant, as long as the surgery happens within two months of admission. If the transplant is delayed beyond that, coverage starts two months before the actual procedure.
If you already have employer group health insurance when you start dialysis, that plan typically pays for your first three months of treatment before Medicare takes over as your primary coverage.
What Medicare Actually Covers
Medicare is divided into parts, each handling different types of care. Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Part B covers doctor visits, outpatient procedures, lab tests, preventive screenings, and medical equipment. Together, these two parts form “Original Medicare.”
Part D covers prescription drugs and is offered through private insurance companies. You can also choose Medicare Advantage (sometimes called Part C), which bundles Parts A, B, and often D into a single plan run by a private insurer, frequently adding extras like dental and vision coverage.
The financial difference between these options is real. A typical enrollee in 2019 spent an estimated $440 per month out of pocket with Medicare Advantage, compared to $579 per month with traditional Medicare, a difference of roughly 18 to 24%. That said, Medicare Advantage plans limit which doctors and hospitals you can use, so the tradeoff isn’t purely financial.
Help for People With Low Incomes
Medicare isn’t free across the board. Part B charges a monthly premium, and there are deductibles, copays, and coinsurance throughout. For people who can’t afford those costs, several assistance programs exist.
The Extra Help program (also called the Low-Income Subsidy) reduces prescription drug costs under Part D. For 2026, an individual qualifies with income below $23,940 and countable resources below $18,090. A married couple qualifies with income below $32,460 and resources below $36,100. If you qualify, you pay significantly less for premiums, deductibles, and copays on medications.
Beyond Extra Help, Medicare Savings Programs run by individual states can cover your Part B premium and, in some cases, deductibles and coinsurance. People who qualify for both Medicare and Medicaid (sometimes called “dual eligibles”) get the most comprehensive assistance, with Medicaid filling in most of the cost-sharing gaps that Medicare leaves behind.