What Is Medicare Part B?

Medicare Part B is the portion of Medicare that helps cover outpatient medical care, including doctor visits, preventive services, outpatient hospital care, laboratory testing, durable medical equipment, mental health services, and many medically necessary healthcare services. Part B is one of the two parts that make up Original Medicare and is administered by the Centers for Medicare & Medicaid Services (CMS).

What is Medicare Part B?

Medicare Part B is federal health insurance that helps pay for medically necessary outpatient healthcare and preventive services.

While Medicare Part A primarily covers inpatient hospital care, Part B focuses on services people receive outside of a hospital stay.

Together, Medicare Part A and Part B form Original Medicare.

Many beneficiaries also enroll in Medicare Part D for prescription drug coverage and may purchase a Medigap policy or choose a Medicare Advantage plan for additional coverage.

What does Medicare Part B cover?

Part B covers many medically necessary and preventive healthcare services, including:

• Primary care and specialist visits
• Outpatient hospital services
• Preventive screenings
• Annual wellness visits
• Vaccinations covered by Medicare
• Diagnostic laboratory tests
• X-rays and imaging
• Durable medical equipment (DME)
• Ambulance services
• Mental health services
• Physical therapy, occupational therapy, and speech-language pathology services when Medicare requirements are met
• Certain home health services

Coverage depends on Medicare rules regarding medical necessity and eligibility.

What doesn't Medicare Part B cover?

Although Part B covers many outpatient services, it generally does not cover:

• Most outpatient prescription drugs
• Routine dental care
• Routine vision exams for eyeglasses
• Most hearing aids and routine hearing exams
• Long-term custodial care
• Cosmetic procedures that are not medically necessary

Beneficiaries often obtain additional coverage through Medicare Part D, Medigap, Medicare Advantage, or separate dental and vision insurance.

Who is eligible for Medicare Part B?

You may qualify for Medicare Part B if you are eligible for Medicare.

Most people become eligible when they:

• Turn age 65.
• Receive Social Security Disability Insurance (SSDI) benefits for the required waiting period.
• Have End-Stage Renal Disease (ESRD) and meet Medicare eligibility requirements.
• Have Amyotrophic Lateral Sclerosis (ALS).

Enrollment may occur automatically for some individuals receiving Social Security benefits, while others must actively enroll.

How much does Medicare Part B cost?

Unlike Medicare Part A, which many people receive without paying a monthly premium because of their work history, most beneficiaries pay a monthly Medicare Part B premium.

Depending on income and circumstances, beneficiaries may also pay:

• An annual deductible.
• Coinsurance for covered services.
• Additional premium adjustments for higher-income beneficiaries under Medicare rules (IRMAA).

Premiums, deductibles, and income-related adjustments are updated periodically.

Medicare Part B vs. Medicare Part A

These two parts of Medicare cover different types of care.

Medicare Part A

Generally covers:

• Inpatient hospital care.
• Skilled nursing facility care following a qualifying hospital stay.
• Hospice care.
• Certain home health services.

Medicare Part B

Generally covers:

• Doctor visits.
• Outpatient care.
• Preventive services.
• Medical equipment.
• Laboratory services.
• Mental health care.
• Many other outpatient medical services.

Together, Parts A and B provide the foundation of Original Medicare.

Medicare Part B vs. Medicare Advantage

Both provide Part B benefits but administer them differently.

Original Medicare Part B

• Administered directly by the federal government.
• Generally allows beneficiaries to see any provider nationwide who accepts Medicare.

Medicare Advantage

• Administered by private insurance companies approved by Medicare.
• Must cover all Medicare Part B services.
• Often includes additional benefits not covered by Original Medicare.
• Frequently uses provider networks and may require prior authorization for certain services.

When can you enroll?

Most people enroll during their Initial Enrollment Period, which generally surrounds their 65th birthday.

Others may qualify for:

• A Special Enrollment Period if they delayed enrollment because they had qualifying employer coverage.
• The General Enrollment Period if they missed their initial opportunity to enroll.

Delaying Part B enrollment without qualifying coverage may result in a late enrollment penalty that can increase monthly premiums.

Why this matters

Medicare Part B covers many of the healthcare services people use most often, including doctor appointments, preventive screenings, outpatient procedures, and medical equipment. Understanding when to enroll, what it covers, and what costs to expect can help beneficiaries avoid enrollment penalties and make informed decisions about additional Medicare coverage.