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15 Things You Didn’t Know About Medicare

Little-known facts to help you save money and make smarter health care coverage decisions

13-minute read

Article 9 out of 15 in Medicare Basics

Kimberly Lankford and Jacqueline Salmon,

Updated July 31, 2026

AARP

Reviewed by

by Xavier Vaughn, MPH

En español

Updated July 31, 2026

Illustration of an older adult holding open a large map designed like a Medicare card against a blue background.

Chris Gash

Key takeaways

Medicare isn’t a one-size-fits-all plan.
If you’re still working, you may not need to sign up at 65.
The program isn’t free and doesn’t cover everything.
But you may be able to get financial aid.
Preexisting conditions won’t affect your coverage.

Ever since President Lyndon B. Johnson signed Medicare into law in 1965, hundreds of millions of older Americans have relied on this program to help pay for health care costs.

Today more than 70 million people are enrolled. More than 9 in 10 are 65 and older.

Medicare has evolved from its original Part A hospital and Part B doctor and outpatient care programs. In 1972, it began covering younger people who qualify because of disabilities. A private insurance alternative now known as Medicare Advantage became law in 1997, and lawmakers passed prescription drug coverage called Part D in 2003.

These days, many find Medicare’s choices, deadlines and rules overwhelming. Here are 15 things you may not know about Medicare that can help you make smarter decisions about your health coverage.

1. You pick your Medicare path

Medicare has four basic parts:

Part A covers inpatient stays in a hospital or skilled nursing center, hospice and some home care.
Part B pays for doctor visits, diagnostic tests, preventive care, some medical equipment and other outpatient services.
Part C, Medicare Advantage, is a Medicare-approved plan from a private insurer.
Part D, also from private insurers, covers prescription meds you take at home and some vaccinations.

When you sign up for Medicare, you’ll have to choose between enrolling in original Medicare or a Medicare Advantage plan. Both require you to enroll in parts A and B as a foundation for your care.

If you select original Medicare, you’ll need to enroll in a Part D prescription plan if you don’t have other drug coverage. Also consider buying a supplemental Medigap policy, which will help pay for your out-of-pocket costs that otherwise don’t have a limit.

If you opt for Medicare Advantage, designed to provide many services people often buy separately with original Medicare, you’ll have to choose the right plan for your needs. Each plan can have different coverage and costs.

Medicare Advantage usually includes Part D drug coverage. And plans generally offer some coverage for dental, hearing and vision care or other services.

The caveats:

Medicare Advantage plans have provider networks, which means in many cases, you can only use doctors who participate in the plan you choose.
To use a specialist, you may need a referral from your primary care physician.
To use some services or get some procedures, you likely will need prior authorization from the insurer.
If you use out-of-network doctors, you may pay more, or all, of the costs.
If you decide you want original Medicare after more than a year in Medicare Advantage, you may be stuck.

You might not be able to buy a Medigap policy later. You have a right to try Medicare Advantage for 12 months, but if you don’t switch to original Medicare within that period, Medigap plans in most states can reject you because of your health or charge you more.

State Health Insurance Assistance Programs (SHIPs), federally financed but locally maintained in your state or territory, offer in-depth, unbiased help for prospective enrollees, their families and caregivers. The toll-free national number, 877-839-2675, can connect you with your local SHIP, or you can find your area’s SHIP through an online directory.

2. You enroll in Medicare through Social Security

The federal government linked Medicare with the Social Security Administration (SSA) from the beginning of Medicare. The SSA oversees Medicare sign-ups and deducts Part B premiums from many enrollees’ Social Security payments.

If you’re already receiving Social Security retirement or disability benefits at least four months before your 65th birthday, SSA will automatically enroll you in original Medicare that starts the month you turn 65. But most people will need to apply to get Medicare, in part because of Social Security’s full retirement age of 67 for those born in 1960 and later.

Your first stop will be the Social Security Administration.

The easiest way to sign up is online. This service is available 24/7, including holidays.

But you’ll have to set up a My Social Security account if you’re not already monitoring your earnings history online through SSA. You can also call or visit your nearest Social Security office or phone SSA at 800-772-1213.

Even if you aren’t ready to sign up for Social Security, you can enroll in Part A and Part B.

But enrolling through SSA is only the first step. You’ll still have to choose between original Medicare and Medicare Advantage.

Then you’ll have to head to Medicare’s Plan Finder to compare the private prescription drug and Medigap plans that pair with original Medicare or Medicare Advantage plans available in your area.

3. You may not need to sign up at 65

While most people become eligible for Medicare at age 65, you might not have to sign up then if you or your spouse is still working and you have health insurance through that employer.

However, even if you have job-based insurance, an employer may require that you enroll in Medicare at 65. Medicare can be a backup for a company’s plan, or it may be first in line to pay your medical bills.

The rules vary by company size, so contact your benefits department for details.

4. But you do need to enroll within a specific time

Medicare has a seven-month initial enrollment period for people turning 65.

It starts three months before the month you turn 65 and ends three months after your birthday month unless you were born on the first of a month. Then Medicare counts your birthday as being in the previous month.

If you get health insurance through the Affordable Care Act marketplace, you’ll have to sign up for Medicare during this enrollment window. The same goes if you:

Are covered under the Consolidated Omnibus Budget Reconciliation Act of 1985, better known as COBRA, which extends a former employer’s coverage.
Have the military's Tricare insurance.
Take part in a retiree health plan.
Or have both retiree and Tricare health coverage.

Special rules apply for retired federal employees covered under the Federal Employees Health Benefits (FEHB) program.

Be careful not to miss the deadline. Unless you or your spouse is working and you have health insurance from that employer, you usually need to sign up for Medicare Part B during that initial enrollment window or you’ll be subject to a late enrollment penalty for as long as you’re on Medicare.

You also have to sign up for Part D coverage within certain time frames if you don’t have similar drug coverage, or you’ll have to pay a separate late enrollment penalty.

5. Medicare has new eligibility restrictions

Immigrants who were in the country legally used to be eligible for Medicare if they met work requirements as well as Medicare age or disability requirements. Immigrants without legal status have never been eligible for Medicare.

But under the budget reconciliation bill signed into law in July 2025, Medicare eligibility was restricted.

The law now limits coverage to U.S. citizens; lawful permanent residents, also known as green card holders; certain Cuban and Haitian immigrants; and citizens of the Marshall Islands, Micronesia and Palau living in the U.S. under Compacts of Free Association, agreements rooted in decades of U.S. oversight of the Pacific islands.

People who don’t meet those requirements are immediately prohibited from enrolling in Medicare. Others already on Medicare under previous rules, including some in humanitarian or temporary protection programs, lose eligibility Jan. 4, 2027.

The Social Security Administration was required to identify affected Medicare enrollees by July 4, 2026, and notify them as soon as possible in a language they understand. But the SSA has not publicly released a count of those affected.

If you have questions about your eligibility, call 800-MEDICARE (1-800-633-4227) or contact your local State Health Insurance Assistance Program.

6. Medicare isn’t free

Medicare foots most — but not all — of the bill for enrollees’ medical costs.

In addition to monthly premiums for Part B, and perhaps Part A if you haven’t paid 10 years total in Medicare taxes, you’ll be subject to deductibles, copayments and coinsurance costs. These are the amounts you pay yourself for services such as doctor visits, diagnostic tests, hospital stays and prescription drugs.

How much you pay will depend on which Medicare option you choose — original or Medicare Advantage — and the specific plan.

7. Medicare doesn’t cover everything

Medicare covers a lot of preventive care and most medical services associated with illnesses.

But original Medicare doesn’t pay for dental care in most cases, eye exams for prescription eyeglasses or contacts, hearing aids, cosmetic surgery, massage therapy, membership fees for the fast-growing area of concierge care and some other services.

For you, that means planning for health care expenses you might not have considered, such as root canals and dental implants, bifocals or even earbuds for your smartphone or smart glasses that can also function as hearing aids.

8. Medicare coverage doesn’t extend outside the U.S.

For the most part, Medicare doesn’t cover you internationally.

It has a few exceptions, including allowing a visit to the nearest hospital, even if it’s across the border, when you have a medical emergency in the United States. If you’re on a cruise near the U.S., some care also may be covered.

A Medigap policy may provide some coverage for foreign travel emergency care. And if you have Medicare Advantage, check the fine print in your evidence of coverage documents.

9. You’ll have to pay for long-term care

More than 3 in 5 adults age 50 and older incorrectly think Medicare will pay for their care if they need to move permanently to a nursing home because of a long-term illness or disability, according to the University of Michigan’s 2025 National Poll on Healthy Aging. It’s one of numerous surveys that show a significant portion of Americans of all ages mistakenly believe that Medicare will pay for long-term care.

Medicare does cover stays up to 100 days in rehabilitation centers following a three-day inpatient hospital stay. Your health care provider must decide that you need daily skilled care, like intravenous fluids, medications or physical therapy.

But Medicare doesn’t pay for assisted living or nursing home care. If you need long-term help, even in your own home, you will have to pay for it.

10. Part D prescription drug costs are capped

If you have Part D prescription coverage, either with original Medicare or Medicare Advantage, your yearly out-of-pocket costs will be limited to $2,100 in 2026 and $2,400 in 2027. Once you reach this limit, you won’t owe a copayment or coinsurance for covered Part D drugs for the rest of the year.

More good news: Drug price negotiations reduced Medicare enrollees’ costs for 10 popular but expensive medications in 2026 and beyond, discounts made possible through a 2022 law that AARP championed. Lower prices for an additional 15 brand-name prescriptions will be available starting Jan. 1.

Fifteen more drugs, including Part B medicines for the first time, are part of the latest round of talks, with lower prices to be announced in the fall. Those negotiated prices will be effective Jan. 1, 2028.

And the bargaining continues every year with new drugs added and some prices renegotiated.

11. A higher income may mean higher premiums

If your household income is above a certain limit, you may end up paying more than the standard monthly premium for your Part B and Part D prescription coverage.

The Centers for Medicare & Medicaid Services decides each year how much higher-income Medicare enrollees will have to pay. The Social Security Administration determines who must make the added payments.

But if you’re affected, you may be able to appeal.

If the SSA believes you qualify for what’s called an income-related monthly adjustment (IRMAA) surcharge, you will get a letter telling you how the amount was calculated, what to do if the data used in the calculation is incorrect and what to do if your income is now lower or you had a life-changing event.

To discuss your case, you can visit a Social Security office or call the SSA number (800-772-1213). To request that the IRMAA be reconsidered, you’ll need to file a Medicare IRMAA Life-Changing Event form.

12. Financial help is available

Depending on your income, the government offers several programs to help you afford your Medicare out-of-pocket costs.

Medicare Savings Programs which the federal government helps finance but state Medicaid agencies administer, assist Medicare beneficiaries with limited incomes and assets in paying for Part B out-of-pocket costs and some Part A costs associated with Medicare. You can apply any time, not just during open enrollment Oct. 15 to Dec. 7.

More than 1 in 5 people with Medicare are eligible for one of the four Medicare Savings Programs, according to a 2025 analysis in the medical journal JAMA Network Open. But from 2018 to 2020, more than 40 percent of people who qualified weren’t enrolled.

Apply through your state’s Medicaid office for these financial assistance programs. Your State Health Insurance Assistance Program has counselors to help you through the application process.

For help with prescription drug costs, Medicare offers the Extra Help program for people with limited income and resources.

13. You’re not stuck with the same plan forever

Every fall — from Oct. 15 to Dec. 7 — people with Medicare can review their Part D or Medicare Advantage coverage and decide if they want to make changes.

If you’re on original Medicare, this annual open enrollment period is the time to review your prescription plan and make sure the medications you take remain covered and affordable.

If you have Medicare Advantage, look for changes in your plan’s provider network, drug list and pharmacy network in case any of your doctors, prescriptions or drugstore locations are dropped or move to a higher-priced tier.

You can’t change your Medicare Advantage plan any time you want. But you can switch plans during open enrollment for any reason, and Medicare Advantage members have an additional open enrollment period Jan. 1 to March 31 that original Medicare enrollees don’t have for Part D.

14. Past health problems won’t affect your coverage

Preexisting health conditions don’t bar anyone from Medicare coverage, nor do they result in higher premiums or copays.

Unlike many types of private insurance, Medicare doesn’t charge more because of your health history.

Your premiums will be the same as everyone else’s for all parts of Medicare, including Part A hospital stays, Part B doctor visits, Medicare Advantage and prescription drug coverage — even as you age and have more health problems.

Private Medigap insurers in most states can charge you more or deny you coverage if you apply after your six-month, once-in-a-lifetime Medigap open enrollment period.

15. You’ll be eligible for Medicare as long as you live

Join our fight to protect Medicare

AARP is working to keep Medicare strong. Here’s how you can help.

Sign up to become an AARP activist for the latest news and alerts on issues you care about.
Find out more about how we’re fighting for you in Congress and across the country.
See the latest AARP research on Medicare.
AARP is your fierce defender on the issues that matter to people 50-plus. Become a member or renew your membership today.

Join our fight to protect Medicare

AARP is working to keep Medicare strong. Here’s how you can help.

Sign up to become an AARP activist for the latest news and alerts on issues you care about.
Find out more about how we’re fighting for you in Congress and across the country.
See the latest AARP research on Medicare.
AARP is your fierce defender on the issues that matter to people 50-plus. Become a member or renew your membership today.

As long as your premiums are paid, Medicare is available until you die.

Contributing: Dena Bunis

This story, originally published Oct. 24, 2023, has been updated with additional items.

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About the authors

Kimberly Lankford is a contributing writer who covers Medicare and personal finance and now writes about insurance for The Wall Street Journal | Buy Side. She wrote about insurance, Medicare, retirement and taxes for more than 20 years at Kiplinger’s Personal Finance and has written for The Washington Post and Boston Globe. She received the personal finance Best in Business award from the Society of American Business Editors and Writers and the New York State Society of CPAs’ excellence in financial journalism award for her guide to Medicare.

Jacqueline Salmon is a book and magazine writer-editor specializing in health and wellness, memoirs and business. She is a former Washington Post reporter and editor who covered finance, business and other topics.

About the reviewer

Xavier Vaughn, an AARP adviser for Medicare programs, previously worked at the National Council on Aging in Arlington, Virginia, and Missouri Connections for Health, based in Columbia, Missouri. He earned his master’s degree in public health from the University of Alabama at Birmingham.