How Medicare Works: Parts, Costs & Enrollment

Medicare is a federal health insurance program primarily for people age 65 and older, along with certain younger people who qualify under specific rules. Original Medicare includes Part A and Part B. Medicare Advantage, also called Part C, is another way to receive Medicare Part A and Part B benefits through a Medicare-approved private plan. Part D helps cover prescription drugs. Some people who use Original Medicare also consider Medigap, which works alongside Original Medicare to help with certain out-of-pocket costs. Your enrollment timing, healthcare needs, location, and current coverage can all affect your choices.

TL;DR: Medicare in Plain English

The biggest mistake is treating all of these choices as though they are the same thing.

They're not.

Once you know what each piece does, Medicare becomes much easier to understand.

What Is Medicare?

Medicare is a federal health insurance program administered by the Centers for Medicare & Medicaid Services (CMS). It primarily serves people age 65 and older, while certain younger people may qualify because of disability or specific medical conditions.

That sounds simple.

Then the letters show up.

Part A.

Part B.

Part C.

Part D.

Then there are Medicare Advantage plans, Medigap policies, prescription drug plans, enrollment periods, provider networks, deductibles, and other rules.

It's a lot to take in.

The good news is that you don't need to learn everything at once.

Start with the structure.

Medicare Part A: Hospital Coverage

Part A is generally the hospital side of Medicare.

It helps cover certain inpatient hospital services, skilled nursing facility care after a qualifying hospital stay, hospice care, and some home health services.

What Can Part A Cover?

Depending on the circumstances and Medicare rules, Part A can help with:

• Inpatient hospital stays
• Skilled nursing facility care
• Hospice care
• Certain home health services

Many people don't pay a monthly Part A premium because they or a spouse paid Medicare taxes long enough while working. That is commonly called premium-free Part A. People who don't qualify for premium-free Part A may be able to buy Part A by paying a monthly premium.

But remember:

Premium-free does not mean cost-free.

A hospital stay can still involve a deductible and other cost-sharing.

For 2026, the standard Part A hospital deductible is $1,736 per benefit period.

Medicare Part B: Medical Coverage

Part B is generally the medical side of Original Medicare.

It helps cover doctors' services, outpatient care, preventive services, durable medical equipment, and other medically necessary services.

Part B usually requires a monthly premium.

For 2026, the standard Part B premium is $202.90 per month for most beneficiaries, although some people pay more depending on income. The amount can change each year.

Part B also has a deductible and coinsurance.

So when you're planning your healthcare budget, don't ask only whether a service is covered.

Ask:

"What will my share be?"

That question can tell you much more.

Medicare Part C: Medicare Advantage

Part C is Medicare Advantage.

Medicare Advantage is another way to receive Medicare Part A and Part B benefits through a Medicare-approved private plan. You must have both Part A and Part B to join a Medicare Advantage plan.

Many Medicare Advantage plans include prescription drug coverage, and some may offer additional benefits such as certain dental, vision, hearing, fitness, or other services. The specific benefits depend on the individual plan.

This is where plan rules become especially important.

Provider Networks

Many Medicare Advantage plans use provider networks.

That can affect which doctors and hospitals you use and what you pay. Some plans may also have referral requirements or require prior authorization for certain services.

Before joining a plan, check the providers you care about most:

• Your primary care doctor
• Your specialists
• Your preferred hospital

A plan's premium may look attractive, but provider access can matter just as much.

Medicare Part D: Prescription Drug Coverage

Part D helps cover prescription drugs.

You can generally get prescription drug coverage through a separate Medicare drug plan when using Original Medicare, or through a Medicare Advantage plan that includes drug coverage.

Every drug plan can have its own:

• Formulary
• Pharmacy network
• Deductible
• Copayments
• Coinsurance
• Coverage rules

A formulary is the plan's list of covered prescription drugs.

This is one reason you should never choose drug coverage based on a generic example.

Use your own medication list.

Check Your Prescriptions Before Enrolling

Write down:

• Medication name
• Dosage
• How often you take it
• Preferred pharmacy

Then check how the plan handles each medication.

One prescription can make a bigger difference to your annual costs than you might expect.

Where Does Medigap Fit?

Medicare Supplement Insurance, commonly called Medigap, is different from Medicare Advantage.

Medigap works alongside Original Medicare. Depending on the policy, it may help pay certain out-of-pocket costs that remain after Original Medicare pays its share.

In most states, Medigap policies are standardized by letter. Policies with the same letter generally offer the same basic benefits, although premiums can vary between insurance companies.

Medigap and Prescription Drugs

Medigap policies generally don't include prescription drug coverage.

If someone has Original Medicare and Medigap and also wants Medicare drug coverage, a separate Part D plan is generally the route to consider.

This is why it helps to understand the difference between:

Original Medicare + Medigap + drug coverage

and

Medicare Advantage

They are different coverage paths.

How the Main Pieces Fit Together

Here's a simple way to picture it.

Medicare.gov describes Original Medicare and Medicare Advantage as the two main ways to get Medicare health coverage.

The right path depends on your circumstances.

There isn't one answer that works for everyone.

What Does Medicare Cost?

This is where many people get caught.

Medicare isn't simply one monthly bill.

Your costs can include:

• Premiums
• Deductibles
• Copayments
• Coinsurance
• Prescription costs
• Other out-of-pocket expenses

Medicare.gov notes that what you pay depends on the coverage you have, the services you receive, and the providers you use.

2026 Cost Snapshot

These are 2026 figures and can change from year to year. Medicare Advantage plans have their own premiums and cost-sharing, while Part D costs also vary by plan and income.

That is why it makes sense to review the current year's information rather than relying on an old brochure or something a friend paid last year.

Why Your ZIP Code Matters

Medicare options aren't identical everywhere.

Medicare Advantage and Part D plans are offered within specific service areas, so available choices can vary by ZIP code or county. Medigap availability and premiums can also vary depending on where you live, the insurance company, and other factors.

This matters when you're helping a parent or spouse too.

A plan that works in one county may not even be available in another.

Use the beneficiary's actual location when researching coverage.

When Should You Enroll?

Timing matters.

For people who are becoming eligible because they are turning 65, the Initial Enrollment Period generally lasts seven months. It begins three months before the month you turn 65 and ends three months after the month you turn 65.

The month you enroll can affect when coverage begins. Missing an applicable enrollment window may also lead to late enrollment penalties in certain situations.

Don't leave this until the final week.

Start by finding your enrollment window.

Then work backward.

What If You're Still Working at 65?

Retirement doesn't always happen at 65.

Some people continue working and remain covered by an employer or spouse's employer.

If you or your spouse have group health plan coverage based on current employment, you may be able to delay Part B and use a Special Enrollment Period later. Confirm how your employer coverage works with Medicare before delaying enrollment.

This is not a place for guesswork.

Your employer's benefits department and Medicare can help you understand how your existing coverage coordinates with Medicare.

What Is Medicare Open Enrollment?

Medicare Open Enrollment takes place from October 15 through December 7 each year. During this period, eligible beneficiaries can make certain changes to Medicare health and drug coverage, with changes generally taking effect January 1 of the following year.

Depending on your current coverage, you may be able to:

• Join a Medicare Advantage plan
• Switch Medicare Advantage plans
• Return from Medicare Advantage to Original Medicare
• Join or change a Medicare drug plan

What you can change depends on the coverage you have and your circumstances.

Open Enrollment is also a good time to look at your current coverage and ask whether anything important has changed.

What Should You Review Each Year?

Don't look only at your premium.

Check the whole picture.

Your Doctors

Are your doctors still available under your coverage?

Your Prescriptions

Are your medications covered under the plan's formulary?

Your Pharmacy

Is your preferred pharmacy still part of the network?

Your Costs

Have premiums, deductibles, copayments, or coinsurance changed?

Your Benefits

Are the benefits you cared about last year still offered?

Your Life

Have you moved, retired, started seeing a specialist, or changed medications?

Medicare recommends reviewing plan changes before the new year because coverage, costs, benefits, providers, and drug coverage can change.

A Simple Medicare Checklist

If you're starting from scratch, keep it simple.

You don't have to figure everything out in one sitting.

Start with the first three.

Then keep moving.

Common Medicare Mistakes

A few mistakes show up again and again.

Choosing by Premium Alone

A low monthly premium doesn't tell you what you'll spend when you use healthcare.

Ignoring Your Medications

Your prescriptions can have a major effect on your drug costs.

Forgetting Provider Rules

Your doctor may not participate in every plan's network.

Assuming Everyone Has the Same Enrollment Rules

Employment, existing coverage, and other circumstances can change your enrollment options.

Waiting Until the Deadline

Last-minute research leaves less time to check the details.

A little preparation can prevent a lot of confusion.

Don't Let Medicare Become a December Problem

If you're approaching 65, start before you're under pressure.

If you're already enrolled, don't wait until the final days of Open Enrollment to look at your plan.

• Gather your documents
• Check your doctors
• Review your prescriptions
• Look at the costs
• Read the plan changes

Then decide.

You may decide to keep what you have.

You may decide to explore another option.

Either is fine.

What matters is knowing why.

Conclusion

Understanding How Medicare Works starts with separating the different pieces. Part A generally covers certain hospital and inpatient care. Part B generally covers medical and outpatient services. Medicare Advantage provides another way to receive Part A and Part B benefits through a Medicare-approved private plan, while Part D helps cover prescription drugs. Medigap is separate supplemental coverage that works alongside Original Medicare.

Once those roles are clear, the next step is personal.

• Look at your doctors
• Look at your medications
• Look at your costs
• Look at your location
• Look at your enrollment dates

You don't need to know every Medicare rule before you begin. You just need enough information to ask the right questions and understand the choices in front of you.

Need Help Making Sense of Medicare?

Start With Clarity65

Medicare information is everywhere.

Getting it to make sense for your situation is the harder part.

Clarity65 works with independent licensed agents who explain Medicare in plain English and help consumers review available coverage. The service is provided at no cost to consumers, and Clarity65 represents multiple carriers rather than just one. Its agents can also stay with clients for yearly plan reviews as coverage and healthcare needs change.

You can start by learning more about Medicare Advantage, Medicare Supplement, or Prescription Drug Plans.

You don't have to walk into the conversation knowing every answer.

Bring your questions.

That's enough to get started.

Important: Clarity65 does not offer every plan available in every area. Information provided is limited to plans it offers in your area. For information about all available options, visit Medicare.gov or call 1-800-MEDICARE. Medicare has neither reviewed nor endorsed this information.

Frequently Asked Questions

Raul Gonzalez

Licensed Agent

Independent licensed Medicare advisor dedicated to plain-English guidance and personalized plan comparisons across leading national carriers.

Clarity65 is not connected with or endorsed by the U.S. government or the federal Medicare program.