What Medicare Is, and Who It Is For
Medicare is the federal health insurance program for people 65 or older who are U.S. citizens or meet residency requirements, plus certain younger people with disabilities. It is run by the Centers for Medicare & Medicaid Services (CMS), and Social Security handles most sign-ups.
Medicare comes in parts, and eligibility for each is a little different:
- Part A (Hospital Insurance) covers inpatient hospital care, skilled nursing facility care after a qualifying stay, hospice and some home health care.
- Part B (Medical Insurance) covers doctor visits, outpatient care, preventive services and durable medical equipment.
- Part C (Medicare Advantage) is a private plan that delivers your Part A and Part B benefits, usually with drug coverage built in.
- Part D is prescription drug coverage sold by private plans.
Parts A and B together are called Original Medicare. Being eligible for Medicare means you can get Parts A and B; the private plans added to it have their own rules, covered below.
Qualifying for Medicare Before 65
Age is the most common path, but Medicare.gov lists three ways to qualify earlier:
- Disability. If you receive Social Security (or Railroad Retirement Board) disability benefits, you are automatically enrolled in Part A and Part B after you have received those benefits for 24 months. Your Medicare card is mailed about 3 months before coverage begins.
- ALS (Lou Gehrig’s disease). People with ALS who are getting disability benefits get Part A and Part B without the 24-month wait.
- End-Stage Renal Disease (ESRD). Permanent kidney failure that requires dialysis or a transplant has its own sign-up path and timing. Medicare.gov has a separate ESRD section, and your dialysis center can help with the paperwork.
If you are under 65 and on Medicare because of a disability, you will get a fresh set of enrollment choices when you turn 65. That second Initial Enrollment Period is worth knowing about, because it can reopen Medigap options. Our enrollment periods guide walks through every window.
Automatic Enrollment vs. Signing Up Yourself
This is where people get caught out. Whether you are enrolled automatically depends on one thing: whether you are already collecting Social Security or Railroad Retirement Board benefits before 65.
| Your situation | What happens |
|---|---|
| Getting Social Security benefits at least 4 months before turning 65 | Enrolled in Part A and Part B automatically. Your welcome package and card arrive about 3 months before coverage starts. |
| Not getting Social Security benefits yet | You must sign up yourself through Social Security during your Initial Enrollment Period. |
| Living in Puerto Rico or outside the U.S. | Part A is automatic, but you must sign up for Part B separately. |
Many Idahoans now wait past 65 to claim Social Security, which means many of them are not enrolled automatically. If that is you, Medicare will not come looking for you. Your Initial Enrollment Period is 7 months long: it starts 3 months before the month you turn 65 and ends 3 months after it. Coverage always starts on the first of a month.
If you are automatically enrolled, you can usually decline Part B if you have qualifying coverage from current work. Do not decline it casually, though: the rules on which employer plans make delaying safe are specific. Our guide to working past 65 explains the employer-size rule and the 8-month window.
Is Part A Premium-Free for You?
For most people, yes. Part A is premium-free if you or your spouse paid Medicare taxes while working for long enough, generally at least 10 years. People who get Medicare before 65 because of a disability also do not pay a Part A premium.
If you do not qualify, you can buy Part A. In 2026 it costs $311 a month if you or your spouse have 30 to 39 quarters of Medicare-covered work, or $565 a month with fewer than 30 quarters. To buy Part A you also have to sign up for Part B. If you have to buy Part A and do not do it when first eligible, a late penalty can apply; see our late enrollment penalties guide.
Part B is not premium-free for anyone. The 2026 standard Part B premium is $202.90 a month, and people with higher incomes pay more through IRMAA. The full 2026 cost picture is in our Medicare costs guide.
Eligibility for Medicare Advantage, Medigap and Part D
Once you have Medicare, you can choose how to receive it. Each option has its own entry requirements, according to Medicare.gov:
- Medicare Advantage (Part C): you need both Part A and Part B, and you must live in the plan’s service area. Plans are approved county by county, so what is available in Ada County may differ from Boise County or Valley County.
- Medicare drug plans (Part D): you need Part A or Part B, and you must live in the plan’s service area.
- Medigap (Medicare Supplement): generally requires Original Medicare, meaning both Part A and Part B. Your strongest buying window is the 6-month Medigap open enrollment period that starts when your Part B begins and you are 65 or older.
To join a Medicare health or drug plan, you also generally must be a U.S. citizen or national, a lawful permanent resident, a Cuban-Haitian entrant, or lawfully living in the U.S. as a Compact of Free Association migrant, and you will need your Medicare Number and your Part A and Part B start dates from your card.
Notes for Idaho Residents
The federal eligibility rules are the same in every state, but two Idaho details are worth knowing early:
- Plan choices depend on your county. Medicare Advantage and Part D lineups are set by service area, so a move between counties can change your options and may open a Special Enrollment Period.
- Idaho has a Medigap birthday rule. Since March 2022, Idaho Medigap policyholders get an annual 63-day guaranteed-issue window starting on their birthday to change Medigap policies. It applies only to people who already hold a Medigap policy. We explain it in Medicare Advantage vs. Medigap in Idaho.
If you are approaching 65, the next step is a timeline. Our turning 65 checklist lays it out month by month, and the enrollment window finder shows which window you are in today.
Not sure which path you are on?
Tell us your birthday month, whether you are still working, and what coverage you have now. We will map your Medicare dates with you, at no cost.
Request a free comparison Call 208-350-9933Frequently Asked Questions
Can I get Medicare before I turn 65?
Yes, in three situations. You can qualify after receiving Social Security disability benefits for 24 months, if you have End-Stage Renal Disease (permanent kidney failure), or if you have ALS. People with ALS get Medicare as soon as their disability benefits begin, without the 24-month wait.
Do I have to sign up for Medicare, or is it automatic?
It depends on whether you already get Social Security or Railroad Retirement Board benefits. If you started those benefits at least 4 months before turning 65, you are enrolled in Part A and Part B automatically and your card arrives about 3 months before coverage starts. If you are not getting benefits yet, you have to sign up yourself through Social Security.
Will I pay a premium for Part A?
Most people do not. Part A is premium-free if you or your spouse paid Medicare taxes while working for long enough, generally at least 10 years. If you do not qualify, you can buy Part A for $311 or $565 a month in 2026, depending on how long you or your spouse paid Medicare taxes.
Can I get Medicare if I am not a U.S. citizen?
Medicare is for people who are U.S. citizens or meet residency requirements. To join a Medicare health or drug plan, Medicare.gov says you generally must be a U.S. citizen or national, a lawful permanent resident, a Cuban-Haitian entrant, or lawfully living in the U.S. as a Compact of Free Association migrant. Social Security can confirm whether your residency history qualifies.
If I am eligible for Medicare, am I eligible for every Medicare plan?
Not automatically. To join a Medicare Advantage plan you need both Part A and Part B and must live in the plan’s service area. To join a standalone drug plan you need Part A or Part B. Medigap policies generally require both Part A and Part B, and outside your open enrollment window an insurer may be allowed to ask health questions.
Related Guides
Coverage pages for this topic: Medicare Advantage · Medicare Supplement · Medicare Part D. Other topics in the Learning Center: Health Insurance (ACA), Life Insurance, Final Expense, Annuities, Long-Term Care, Disability Insurance, Supplemental Health, Short-Term Medical, Travel Insurance.
Sources
- CMS — 2026 Medicare Parts A & B Premiums and Deductibles (fact sheet)
- Medicare.gov — Get started with Medicare
- Medicare.gov — How do I sign up for Medicare?
- Medicare.gov — When does Medicare coverage start?
- Medicare.gov — Medicare costs (2026)
- Medicare.gov — Joining a plan (enrollment periods)
- Medicare.gov — What’s Medicare Supplement Insurance (Medigap)?
- Medicare.gov — Avoid late enrollment penalties
Figures are labelled with the year they apply to and were checked against the official sources above on the review date. Rules and amounts change; confirm current figures with the agency that publishes them. This guide is general education, not individual advice.