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  3. Medicare 101
Medicare 101: Your guide to the basics

When you’re just getting started with Medicare, getting the information you need can help you feel confident you’re making the best choice for you. That’s where HealthPartners comes in. We’ve helped thousands of people learn the basics of Medicare. We’re here to help you, too.

Learn the basics of Medicare video: A woman wearing a headset smiles as she explains Medicare to a caller over the phone
On this page, you can find information about: Original Medicare coverage guide

Medicare is a federal health insurance program that helps cover health care costs for those who qualify. The coverage you can receive directly from the U.S. government is called Original Medicare, also known as Medicare Parts A and B. Original Medicare has premiums, deductibles, copays and coinsurance costs.

Learn more about common health insurance terms Medicare Part A

Medicare Part A covers certain hospital-related expenses you may be charged during a traditional hospital stay, for home health care or for care received in a skilled nursing facility. These expenses can include room fees, meals and more. Part A also covers necessary medical supplies and drugs that are provided in these circumstances.

Medicare Part A doesn’t cover doctor fees, or hospital fees considered medically unnecessary, such as private duty nursing, the television or telephone in your room (if separate charges apply), or personal care items such as razors and slippers.

Most people don’t pay a monthly premium for Part A. But when you need care, you’re responsible for certain deductibles, copays and coinsurance.

Medicare Part B

Medicare Part B covers medical expenses like routine doctor visits, outpatient services and some diagnostic screenings. Part B may also cover some medicines administered during your visit and a limited number of outpatient prescription drugs under certain conditions.

Most people pay a monthly premium for Part B. And when you need care, you’re also responsible for certain deductibles, copays and coinsurance.

Types of private Medicare plans

Original Medicare covers the basics but not much more. There are many important services that Original Medicare doesn’t include, like prescription drug coverage, routine hearing exams and eye care.

When you need more coverage than Original Medicare, consider enrolling in a plan that includes additional coverage from a private insurer like HealthPartners.

Here are some things to keep in mind about private Medicare plans:

  • Your choice of plans will depend on where you live. Different plans are offered in different counties.
  • Each plan has its own premium, deductible, copay and out-of-pocket maximum amounts. It’s a good idea to get familiar with these common health insurance terms, so when you’re reviewing what to consider when comparing Medicare plans, you can choose one that meets your needs.
  • Once you enroll in a private Medicare plan, you don’t need to renew it each year. But you’ll have opportunities to switch Medicare plans if your needs change.
Standing in a clinic waiting room, an older man looks thoughtfully at a pamphlet and listens to his doctor as she gives advice. Learn more about comparing Medicare plans
Medicare Supplement (Medigap) plans

Medicare Supplement plans help bridge the gaps between what Original Medicare covers and your total expenses for deductibles, copays and coinsurance. When you receive care, Original Medicare will pay its share for covered services. Then your Medicare Supplement plan will pay its share. You’ll be responsible for any remaining cost not covered by your Supplement plan.

You’ll pay a premium for your Medicare Supplement plan in addition to your Part B premium.

Medicare Advantage plans

Medicare Advantage plans combine the coverage of Original Medicare Parts A and B into one plan (often called Part C), giving you the convenience of one plan for all your coverage. They also usually offer additional benefits and perks on top of Original Medicare, such as dental. Most Medicare Advantage plans typically include Part D prescription drug coverage, too.

You’ll usually pay a premium for your Medicare Advantage plan in addition to your Part B premium. But your Part A and Part B deductibles, copays and coinsurances will be replaced by those from your Medicare Advantage plan.

Medicare Cost plans

Medicare Cost plans also offer additional benefits and perks on top of Original Medicare. You’ll typically pay a premium for your Medicare Cost plan in addition to your Part B premium. But while Medicare Advantage plans take the place of Original Medicare, Cost plans work alongside Original Medicare.

At in-network providers, your Part A and Part B deductibles, copays and coinsurances will be replaced by those from your Medicare Cost plan. But if you go out of network for care, your Original Medicare benefits will kick in for covered services (in other words, you’ll be responsible for Original Medicare’s cost-sharing amounts).

Medicare Part D plans

Medicare Part D plans help cover the cost of outpatient prescription drugs, like the ones you take at home, plus several vaccines. You can enroll in a stand-alone Part D plan to add drug coverage to Original Medicare, a Medicare Supplement plan or a Medicare Cost plan.

If you want the convenience of one plan for all your coverage, most Medicare Advantage plans include Part D coverage. But if you don’t enroll in any plan that has Part D coverage, you’ll be responsible for the full cost of all your prescriptions.

Medicare eligibility

To be eligible for Medicare, you must be a United States citizen or lawfully present in the United States. You must also:

  • Be age 65 or over, OR
  • Be under age 65 with certain disabilities, OR
  • Have end-stage renal disease (eligible for Medicare Advantage plans only)
When you can enroll in Medicare

Starting when you turn 65, you’ll have several opportunities to enroll in Medicare. But if you don’t enroll during your first enrollment window (around your 65th birthday), you may have to pay a late-enrollment penalty for Part B or Part D. It’s a good idea to learn about all enrollment windows so you can take action when the time is best for you.

A senior woman lounges in a chair on a balcony while comparing Medicare plans on her tablet.

Your Initial Enrollment Period is your opportunity to enroll in Medicare. During your IEP, you can enroll in Original Medicare (Parts A and B) or a private Medicare plan.

Your IEP is a seven-month window around your 65th birthday:

  • The three months before the month you turn 65
  • The month of your birthday
  • The three months after the month you turn 65

For example, if your birthday falls on June 10, your IEP would start on March 1 and end on September 30. For coverage to start the month you turn 65, you must sign up in the three months before the month of your birthday.

If you don’t enroll in Original Medicare Part B during your IEP, you may pay a penalty for late enrollment. The late-enrollment penalty takes the form of higher premiums and lasts for as long as you have Part B.

If you don’t sign up for Medicare Part A or Part B when you’re eligible, you can apply for Medicare for the first time using the General Enrollment Period from January 1 through March 31 every year. You can also sign up for most private Medicare plans at this time.

This enrollment period is usually only available to people who didn’t sign up during their Initial Enrollment Period and who aren’t eligible for a Special Enrollment Period (see below). Coverage would begin the month after you sign up. You may have to pay higher premiums due to late enrollment.

A Special Enrollment Period lets you enroll in Original Medicare or most private Medicare plans outside of your IEP and the GEP due to certain circumstances, such as losing your employer coverage after the age of 65.

If you qualify for an SEP, you have a certain amount of time to enroll. The length of time is determined by the type of SEP you are qualified for, but it’s generally between two and three months.

If you or your spouse works past the age of 65, you may not need Medicare until your employer health coverage ends. Every situation is unique, and it’s important to weigh your options to ensure you’re getting the coverage you need.

For example, you might consider:

  • Combining an employer health plan and Medicare – It’s possible to have both Medicare and an employer health plan after age 65. One type of plan does not replace the other. Instead, they can work together to ensure your health care needs and expenses are covered.
  • Delaying Medicare Parts A and B – Depending on the size of your employer(s), you may be able to delay both Medicare Parts A and B without penalty as long as you or your spouse have employer health coverage. When you do enroll in Medicare, it must be within eight months of losing your health coverage or your last day of work, whichever comes first (see SEPs above).
  • Enrolling only in Part A – Most people don’t pay a monthly premium for Medicare Part A, so you could enroll while you or your spouse is still working. However, if you have a health savings account (HSA), be aware that once you enroll in any part of Medicare, you can no longer make contributions to it.
How to enroll in Medicare

Many people are automatically enrolled in Original Medicare (Part A and Part B) once they're eligible. But not everyone is.

You'll be automatically enrolled in Original Medicare if:

  • You're receiving Social Security benefits or Railroad Retirement Board benefits when you turn 65; OR
  • You're eligible for Medicare because of a disability or medical condition

You must enroll yourself in Original Medicare if you're not receiving Social Security benefits when you become eligible for Medicare. There are three ways you can enroll yourself in Original Medicare:

  1. Enroll online through the Social Security Administration
  2. Call the Social Security Administration at 800-772-1213 (TTY 800-325-0778), 8 a.m. to 7 p.m., Monday - Friday
  3. Enroll in person at your local Social Security office

For private Medicare plans, you can enroll at the same time as your automatic enrollment or self-enrollment in Original Medicare. If you first enrolled in Original Medicare but later want to enroll in a private Medicare plan, you’ll have an opportunity to do so every year during the Annual Enrollment Period (AEP).

Legal information

Last updated October 2026

Y0095_005698_M Accepted 09/26/26
H2422_005698_M Accepted 09/26/26
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