What Is Medicare Part B? Coverage, Costs and How It Works

Medicare Part B is the outpatient medical insurance component of Original Medicare. It covers physicians' services, outpatient hospital care, durable medical equipment, certain home health services and preventive screenings. The Centers for Medicare & Medicaid Services (CMS) sets Part B costs annually under the Social Security Act. 

In 2026, most enrollees pay a standard monthly premium of $202.90 and a $283 annual deductible. After meeting the deductible, Part B pays 80% of the Medicare-approved amount for most covered services. You're responsible for the remaining 20% with no annual out-of-pocket maximum under Original Medicare, meaning a serious health event can lead to substantial costs without supplemental coverage. 

To limit that exposure, many beneficiaries add a Medicare Supplement (Medigap) plan or join a Medicare Advantage plan that bundles Part A, Part B and usually Part D into a single plan.

Medicare Part B covers two categories of care: medically necessary services and preventive care. Medically necessary services cover anything a physician orders to diagnose or treat a health condition. Preventive care includes screenings and vaccinations that catch or prevent illness before it worsens. After meeting the $283 annual deductible in 2026, Part B pays 80% of Medicare-approved costs for most covered services, and you pay the remaining 20%.

Medicare Part B pays for medically necessary outpatient services a physician orders to diagnose or treat a condition. Coverage applies when the service meets accepted standards of medical practice. After your $283 deductible in 2026, Part B covers 80% of the Medicare-approved amount for most of these services. The 20% you pay has no annual ceiling without supplemental coverage.

Medicare Part B covers preventive services at no cost when your provider accepts Medicare assignment, meaning the $283 deductible doesn't apply to these services. Coverage varies based on your age, sex and personal health history. Your "Welcome to Medicare" preventive visit is available at no cost within the first 12 months of Part B enrollment. Annual wellness visits are also covered at no charge after your first year.

Medicare Part B leaves meaningful coverage gaps that affect nearly all enrollees. Routine dental, vision and hearing care aren't covered under Original Medicare, nor is long-term custodial care or most prescription drugs you take at home. If you know what Medicare doesn't cover, you can decide whether a Medicare Advantage plan or Medigap insurance can fill the gaps that matter most. 

• Long-term custodial care: Extended nursing facility stays and in-home help with daily activities such as bathing and dressing aren't covered. Long-term care insurance or Medicaid may cover these costs.
• Dental care: Routine cleanings, fillings, extractions and dentures are excluded. Medicare Advantage plans and standalone dental coverage are the main alternatives.
• Vision care: Routine eye exams for glasses or contact lenses aren't covered. Medicare does cover eye exams for medical conditions such as diabetic retinopathy and glaucoma screenings for high-risk patients.
• Hearing aids: Hearing aids and the exams to fit them aren't included under Original Medicare. Many Medicare Advantage plans add hearing benefits.
• Cosmetic surgery: Procedures without documented medical necessity aren't covered.
• Most prescription drugs: Self-administered medications you take at home require a separate Medicare Part D plan. Part B covers a narrow category of drugs administered in a clinical setting, such as chemotherapy infusions.
• Care outside the United States: Original Medicare generally doesn't cover health care received outside the U.S. or its territories. Some Medigap plans cover 80% of emergency care abroad after a $250 deductible, up to a $50,000 lifetime limit.

Medicare Part B eligibility starts at age 65 for most Americans. You can qualify earlier if you've received Social Security Disability Insurance (SSDI) benefits for 24 consecutive months, or if you have End-Stage Renal Disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS). Your Initial Enrollment Period spans 7 months: 3 months before your 65th birthday month, your birthday month and 3 months after. Missing this window triggers a permanent late enrollment penalty.

Medicare Part B's total cost goes beyond a single monthly premium. Your actual spending depends on how often you use covered services, whether your income triggers an IRMAA surcharge and whether you carry supplemental coverage to cap unlimited co-insurance. Part B has no annual out-of-pocket maximum under Original Medicare.

The standard 2026 Medicare Part B premium is $202.90 monthly for most enrollees. Higher-income beneficiaries pay an Income-Related Monthly Adjustment Amount (IRMAA) surcharge on top of the standard premium. The Social Security Administration (SSA) determines IRMAA using your 2024 modified adjusted gross income (MAGI). Surcharges begin when individual MAGI exceeds $109,000 or joint MAGI exceeds $218,000. Total premiums reach up to $689.90 monthly at the highest income bracket.

Source: CMS Fact Sheet: 2026 Medicare Parts A & B Premiums and Deductibles, cms.gov, November 14, 2025. IRMAA is based on 2024 MAGI. Married beneficiaries who file separate returns but lived with their spouse pay different rates; contact SSA for details. 

Part B premiums are deducted directly from Social Security checks for most beneficiaries. If you haven't claimed Social Security yet, CMS bills you quarterly. Enrolling in a Medicare Advantage plan doesn't waive the $202.90 Part B premium. Some Medicare Advantage plans offer a "Part B giveback" benefit that covers part of this cost, reducing your net monthly premium.

The 2026 Medicare Part B annual deductible is $283. You pay the first $283 of Medicare-approved costs each calendar year before Part B coverage begins. After that, Part B covers 80% of the Medicare-approved amount for most services; you pay the remaining 20%. Preventive services are exempt from this cost-sharing when your provider accepts Medicare assignment. Part B has no cap on your annual co-insurance under Original Medicare. 

To limit that unlimited 20% exposure, many beneficiaries add Medicare Supplement Insurance (Medigap). Medigap plans average $189 monthly at age 65 and $238 monthly by age 75, based on MoneyGeek's analysis of 2026 Medigap plan data. The 6-month Medigap Open Enrollment Period, which begins the month you turn 65 and enroll in Part B, guarantees coverage regardless of health history.

Medicare Part B covers the outpatient care most beneficiaries use every day: doctor visits, preventive screenings and durable medical equipment, but leaves real gaps in dental, vision and prescription drug coverage. The $283 annual deductible and unlimited 20% co-insurance can add up quickly without supplemental coverage. If you know Part B's 2026 costs, exclusions and enrollment rules before you sign up, it will help you choose the right combination of coverage and avoid unexpected bills.

We've answered some of the most frequently asked questions Medicare beneficiaries and new enrollees have about Medicare Part B: