What Is Medicare Part B?
Medicare Part B is the medical insurance portion of Original Medicare. It works alongside Medicare Part A to form the foundation of your Medicare coverage. While Part A handles inpatient hospital care, Part B covers the outpatient and medical services you use on a day-to-day basis.
Unlike Part A, which is free for most people, Part B requires a monthly premium. In 2026, the standard premium is $202.90 per month. This amount is typically deducted directly from your Social Security benefit if you are receiving it. If you are not yet receiving Social Security, you will receive a bill from Medicare.
One of the most important things to understand about Part B is that it has no out-of-pocket maximum. After you meet the annual deductible, you pay 20% of the Medicare-approved amount for most covered services, with no cap. This is why many people choose to add a Medigap supplement or enroll in a Medicare Advantage plan to limit their exposure.
What Medicare Part B Covers
Doctor visits and outpatient care
Visits to your primary care physician, specialists, and other healthcare providers. Includes office visits, consultations, and second opinions.
Preventive services
Annual wellness visits, flu shots, cancer screenings (mammograms, colonoscopies, prostate exams), cardiovascular screenings, diabetes screenings, and many other preventive tests at no cost to you.
Outpatient surgery and procedures
Surgeries and procedures performed in an outpatient setting, including ambulatory surgical centers. You are not admitted overnight.
Emergency room visits
Emergency department care. Note: if you are admitted to the hospital from the ER, Part A takes over for the inpatient stay.
Ambulance services
Ground and air ambulance transportation when other transportation would endanger your health. Coverage applies when transport is to the nearest appropriate facility.
Durable medical equipment (DME)
Wheelchairs, walkers, hospital beds, oxygen equipment, blood sugar monitors, and other equipment prescribed by your doctor for home use.
Mental health services (outpatient)
Individual and group therapy, psychiatric evaluations, and outpatient mental health treatment. Part B covers 80% after the deductible.
Home health care
Part-time skilled nursing care and therapy services ordered by a physician for homebound patients. Part B covers home health when no prior hospitalization is required.
Diabetes supplies and education
Blood sugar testing supplies, therapeutic shoes for people with diabetes, and diabetes self-management training programs.
Clinical research and trials
Routine costs associated with approved clinical research studies, including some experimental treatments.
What Part B Does Not Cover
Routine dental care (cleanings, fillings, dentures)
Routine vision exams and eyeglasses
Hearing aids and routine hearing exams
Cosmetic surgery
Acupuncture (except for chronic low back pain)
Long-term custodial care
Prescription drugs taken at home (covered by Part D)
Care received outside the United States (with limited exceptions)
Routine foot care (with limited exceptions for diabetics)
Dental, vision, and hearing are the three most common gaps people discover after enrolling in Original Medicare. Many Medicare Advantage plans include these benefits. See our coverage pages for dental, vision, and hearing aids for full details.
Medicare Part B Costs in 2026
| Cost Item | Amount |
|---|---|
| Part B Premium | $202.90/month |
| Annual Deductible | $283/year |
| Coinsurance After Deductible | 20% |
| Preventive Services | $0 |
| Outpatient Mental Health | 20% after deductible |
| Late Enrollment Penalty | 10% per 12-month period |
Source: Centers for Medicare and Medicaid Services, 2026. For the full cost reference including Part A, see our Medicare Costs at a Glance page.
IRMAA: Higher-Income Premiums
If your income exceeds certain thresholds, you will pay more than the standard $202.90/month premium. This additional amount is called the Income-Related Monthly Adjustment Amount, or IRMAA. Social Security uses your tax return from 2 years ago to determine whether IRMAA applies to you.
| 2026 Individual Income | Monthly Part B Premium |
|---|---|
| $109,000 or less (individual) | $202.90/month |
| $109,001 to $136,000 | $276.90/month |
| $136,001 to $163,000 | $389.90/month |
| $163,001 to $500,000 | $502.90/month |
| Above $500,000 | $594.90/month |
If your income has dropped significantly since the tax year Medicare is using (for example, due to retirement, divorce, or loss of a spouse), you can appeal your IRMAA determination by filing Form SSA-44 with the Social Security Administration.
Eligibility and Enrollment
You are eligible for Part B at age 65 if you are eligible for Part A. Unlike Part A, Part B is optional, but most people should enroll when first eligible to avoid the late enrollment penalty.
Your Initial Enrollment Period (IEP) is the same 7-month window as Part A: 3 months before your 65th birthday month, your birthday month, and 3 months after. If you miss this window without qualifying coverage, you must wait for the General Enrollment Period (January 1 through March 31 each year), with coverage starting July 1.
If you have active employer coverage through a current employer (yours or your spouse's) with 20 or more employees, you can delay Part B without penalty. You will have a Special Enrollment Period of 8 months after that coverage ends to enroll in Part B.
COBRA and retiree health coverage do not qualify as active employer coverage for the purpose of delaying Part B. If you rely on COBRA after leaving a job, you should enroll in Part B during your IEP or SEP to avoid the permanent penalty. See our Enrollment Timeline for the full breakdown.
The 20% Gap Problem
Part B pays 80% of the Medicare-approved amount for most covered services after you meet the annual deductible. You are responsible for the remaining 20%, and there is no out-of-pocket maximum. For most routine care, this is manageable. But for major outpatient procedures, cancer treatment, or ongoing specialist care, 20% can add up to thousands of dollars.
There are two main ways to address this gap:
Medigap Supplement Plans
Medigap plans (also called Medicare Supplement Insurance) pay after Original Medicare pays, covering some or all of your Part B coinsurance depending on the plan. Plan G is the most comprehensive option available to new enrollees. See our Do I Need a Supplement? guide.
Medicare Advantage Plans
Medicare Advantage plans replace Original Medicare and typically have fixed copays instead of 20% coinsurance, plus an annual out-of-pocket maximum. They often include extra benefits like dental, vision, and hearing. See our Original vs. Advantage comparison.
Frequently Asked Questions
Concerned About the 20% Coinsurance?
A licensed Medicare specialist can show you your options for capping your out-of-pocket costs at no charge to you.