What is Medicare Part B? Complete guide [2026]

Updated: 2026-09-29

Medicare Part B is the medical insurance part of Original Medicare. It covers doctor visits, outpatient care, lab work, medical equipment and many preventive screenings (Medicare.gov). In 2026, most people pay a standard Part B premium of $202.90 a month and a $283 yearly deductible (Medicare.gov). After you meet the deductible, you usually pay 20% of the Medicare-approved amount for covered services.

That's the short answer. The longer answer is mostly about timing.

At Medicare Broker Directory, we hear the same Part B questions over and over. Should I sign up if I'm still working? Why is my premium higher than my neighbor's? What will the 20% cost me? Do I still need Part B if I pick Medicare Advantage? This guide answers each one with real numbers and plain examples.

This article is for information only. For advice about your own situation, talk with a licensed Medicare broker.

Quick summary

1. Medicare Part B is medical insurance for outpatient care and preventive services. Part A covers inpatient hospital stays.
2. The 2026 standard Part B premium is $202.90 a month, and the deductible is $283 a year (Medicare.gov).
3. After the deductible, you generally pay 20% of the Medicare-approved amount for most Part B services (Medicare.gov).
4. Your first chance to sign up is a 7-month Initial Enrollment Period built around your 65th birthday (Medicare.gov).
5. If you sign up late without qualifying coverage, your premium can go up 10% for each full 12-month period you went without Part B (Medicare.gov).
6. Our view: Part B is less a "should I buy it" choice and more a "when should it start" choice. The right answer depends on whether you have health coverage from a job you or your spouse still hold.

Understanding Part B

Original Medicare has two parts. Part A is hospital insurance. Part B is medical insurance. Together they cover most of the care people need, but they pay for different things.

Part B covers two broad groups of services (Medicare.gov). The first is medically necessary care, meaning services or supplies you need to diagnose or treat a health condition. The second is preventive care, meaning services that help catch illness early or keep it from starting, like flu shots and certain cancer screenings.

In day-to-day terms, Part B is what pays when you:

• See your primary care doctor or a specialist
• Get blood work or an X-ray
• Have outpatient surgery
• Need a walker, wheelchair or other durable medical equipment
• Get outpatient mental health care
• Take an ambulance ride that meets Medicare's rules

You can check whether a specific test or item is covered on Medicare's coverage lookup pages. Many preventive services cost you nothing if your provider accepts assignment (Medicare.gov). "Accepts assignment" means the provider agrees to take the Medicare-approved amount as full payment.

Part B vs. Part A at a glance

Here's the part people miss. Unlike Part A, Part B almost always has a monthly premium. That's why so many people wonder if they can skip it or delay it.

Sometimes you can. If you or your spouse are still working and have group health coverage through that job, you may be able to wait without a penalty (Medicare.gov). But if you don't have that kind of coverage, delaying usually costs more over time.

Part B also matters if you want Medicare Advantage. To join a Medicare Advantage Plan, you need both Part A and Part B (Medicare.gov). And you generally keep paying your Part B premium while you're in the plan. Plan options and costs vary by location.

Part B costs and rules to know

These are the points we walk clients through most often. Each one affects what you'll actually pay.

• The standard monthly premium in 2026 is $202.90 (Medicare.gov). Some people pay more because of income.
• Higher earners pay an extra amount called IRMAA (Income-Related Monthly Adjustment Amount). Social Security bases it on the modified adjusted gross income on your tax return from 2 years ago (SSA.gov). A 2026 premium usually reflects your 2024 income.
• If your income dropped because of a life change like retirement, you can ask Social Security to use newer income information (SSA.gov). We see this come up often in the first year after someone stops working.
• The $283 deductible applies once per year (Medicare.gov). After that, your share is usually 20% of the Medicare-approved amount.
• Premiums are usually taken out of your Social Security check if you get benefits (Medicare.gov).
• If your income and savings are limited, a Medicare Savings Program may help pay your Part B premium (Medicare.gov).
• Part B doesn't cover most prescription drugs you pick up at a pharmacy. That's Part D's job. Part B does cover some drugs you get in a doctor's office or clinic (Medicare.gov).
• A late sign-up penalty can add 10% to your premium for each full 12-month period you could have had Part B but didn't. In most cases you pay it for as long as you have Part B (Medicare.gov).
• Your one-time Medigap Open Enrollment Period starts when you're 65 or older and enrolled in Part B. It lasts 6 months (Medicare.gov). So your Part B start date also sets the clock for Medigap.

That last point surprises people. Your Part B start date affects more than just Part B.

How Medicare Part B works

Here's the process from sign-up to paying a bill, step by step.

Step 1: Know your enrollment window

Most people first qualify at 65. Your Initial Enrollment Period is 7 months long. It starts 3 months before the month you turn 65, includes your birthday month and ends 3 months after (Medicare.gov).

Step 2: Sign up, or confirm you're already enrolled

If you already get Social Security benefits at least 4 months before you turn 65, you'll usually be enrolled in Parts A and B automatically (Medicare.gov). If not, you sign up through Social Security, online or by phone (SSA.gov).

Step 3: Check when coverage starts

If you sign up in the 3 months before your birthday month, coverage starts the first day of your birthday month. If you sign up in your birthday month or later, coverage starts the first of the month after you sign up (Medicare.gov).

Step 4: Get care and pay your share

You show your Medicare card at a provider that accepts Medicare. You pay toward the deductible first. Then Medicare pays most of the approved amount, and you pay the rest.

Here's a simple example using 2026 figures. Say your first Part B service of the year has a Medicare-approved amount of $500. You pay the first $283 to meet your deductible (Medicare.gov). That leaves $217. Your 20% share of that's $43.40. So you'd pay $326.40 total, and Medicare pays $173.60.

For the rest of the year, you'd pay just 20% on most covered services. A $500 approved bill would cost you $100.

Step 5: Decide on extra coverage

That 20% share keeps applying bill after bill. So most people we work with pick one of two paths. They add a Medigap policy to Original Medicare, or they join a Medicare Advantage Plan. Both require Part B. Which plans you can get, and what they cost, vary by location.

A real-world scenario we see often

A client turns 65 while still working at a company with 50 employees. Her group plan covers her. For employers with 20 or more employees, the group plan generally pays first and Medicare pays second (Medicare.gov). So she can often delay Part B, skip the premium and use a Special Enrollment Period later.

But if that same employer had fewer than 20 employees, Medicare would usually pay first (Medicare.gov). Skipping Part B could leave big gaps. This single detail changes the whole decision. So we always ask about employer size before anything else.

One more detail to know. COBRA and retiree coverage don't count as coverage from current employment for the Special Enrollment Period (Medicare.gov). People who rely on COBRA and wait on Part B can end up with a penalty.

Part B dates and dollar amounts

• The standard Medicare Part B premium is $202.90 per month in 2026 (Medicare.gov).
• The Medicare Part B deductible is $283 per year in 2026 (Medicare.gov).
• After the deductible, you typically pay 20% of the Medicare-approved amount for most Part B services (Medicare.gov).
• The Initial Enrollment Period lasts 7 months, starting 3 months before the month you turn 65 (Medicare.gov).
• The Part B late enrollment penalty is 10% for each full 12-month period you could have had Part B but didn't (Medicare.gov).
• The General Enrollment Period runs January 1 to March 31 each year (Medicare.gov).
• Open enrollment for Medicare Advantage and drug plans runs October 15 to December 7 each year (Medicare.gov).

Frequently asked questions

Is Medicare Part B free?

No. Most people pay a monthly premium for Part B, and the standard amount in 2026 is $202.90 (Medicare.gov). People with higher incomes pay more. People with limited income and savings may qualify for a Medicare Savings Program that helps pay the premium (Medicare.gov).

What does Medicare Part B cover?

Medicare Part B covers medically necessary services and preventive care. That includes doctor visits, outpatient care, lab tests, durable medical equipment and many screenings (Medicare.gov). It doesn't cover most prescription drugs from a pharmacy, which fall under Part D.

Do I need Medicare Part B if I'm still working?

Not always. If you or your spouse have group health coverage through current employment, you may be able to delay Part B and sign up later during an 8-month Special Enrollment Period without a penalty (Medicare.gov). Employer size matters, because Medicare usually pays first when an employer has fewer than 20 employees (Medicare.gov).

What happens if I sign up for Part B late?

If you didn't have qualifying coverage, your monthly premium can go up 10% for each full 12-month period you could have had Part B but didn't (Medicare.gov). In most cases, you'll pay that penalty for as long as you have Part B. You may also have to wait for the General Enrollment Period, which runs January 1 to March 31.

Why is my Part B premium higher than the standard amount?

Your premium may include an Income-Related Monthly Adjustment Amount, or IRMAA. Social Security sets it using the modified adjusted gross income on your tax return from 2 years ago (SSA.gov). If your income dropped because of a life change like retirement, you can ask Social Security to review it.

Do I still pay for Part B if I've Medicare Advantage?

Yes, in most cases. You need both Part A and Part B to join a Medicare Advantage Plan (Medicare.gov), and you generally keep paying your Part B premium. Plan costs and availability vary by location.

Next steps

You now know what Medicare Part B is, what it covers and what it costs in 2026. You know the premium is $202.90 a month and the deductible is $283. You know when you can sign up. And you know why your employer coverage, or lack of it, shapes the timing.

The next step is simple. Write down your 65th birthday month and count back 3 months. That's when your Initial Enrollment Period opens. If you're still working, ask your HR department how many employees your company has and whether your plan pays first or second after Medicare.

Then talk it through with someone who does this every day. You can find a licensed Medicare broker near you on Medicare Broker Directory and compare Medigap and Medicare Advantage options in your area. A local broker can check which plans are available where you live and explain the tradeoffs in plain terms.

This article is for informational purposes only and isn't a substitute for advice from a licensed Medicare broker. Medicare Broker Directory isn't connected with or endorsed by the U.S. Government or the federal Medicare program.

Medicare has neither reviewed nor endorsed this information.

Federal Government Disclaimer: This website is not connected to or endorsed by the federal government or the federal Medicare program. Medicare Broker Directory is an independent resource. Medicare.gov is the official U.S. government Medicare website.

Review Note: A licensed reviewer checks this article before it's published. All statistics and benefit claims are verified against current CMS guidelines.

Citations: Medicare.gov | CMS.gov | NCOA