Medicare Part B, the medical insurance component of Medicare, covers essential outpatient services including doctor visits, preventive care, medical equipment, and many other healthcare services that keep you healthy outside the hospital. While Part A focuses on inpatient care, Part B protects you from the costs of the medical services you'll use most frequently throughout retirement.

Comprehensive Part B Coverage

Part B covers a wide array of medically necessary services and supplies. Doctor visits include appointments with primary care physicians, specialists, and surgeons for diagnosis and treatment of illness or injury. Whether you need care for chronic conditions like diabetes and heart disease or acute problems like infections and injuries, Part B provides coverage.

Outpatient care encompasses emergency room visits (when you're not admitted), ambulance services, outpatient hospital services, and outpatient mental health care. You're covered for diagnostic tests like X-rays, MRIs, and blood work, as well as therapeutic procedures performed in outpatient settings.

Preventive services form a crucial Part B benefit, often available at no cost to you. These include annual wellness visits, cardiovascular disease screening, diabetes screening and self-management training, cancer screenings (mammograms, colonoscopies, prostate cancer screening), bone mass measurements, and vaccines including flu shots, pneumonia vaccines, and COVID-19 vaccines.

Durable medical equipment such as wheelchairs, walkers, hospital beds, oxygen equipment, and diabetic supplies are covered when medically necessary and prescribed by your doctor. Part B also covers prosthetic devices, orthotics, and certain home medical equipment needed to manage your health conditions.

Additional covered services include physical therapy, occupational therapy, speech-language pathology, clinical laboratory services, some home health services, and limited outpatient prescription drugs like certain vaccines and medications administered by your provider.

2025 Part B Premium and Deductible

For 2025, the standard Medicare Part B monthly premium is $185, representing a $10.30 increase from the 2024 premium of $174.70. This 5.9% increase reflects rising healthcare costs and is automatically deducted from Social Security benefits for most beneficiaries. If you don't receive Social Security, you'll receive quarterly premium bills from Medicare.

The Part B annual deductible for 2025 is $257, up $17 from the 2024 deductible of $240. You must pay this deductible each calendar year before Medicare begins paying its share of covered services. Unlike Part A's benefit period structure, Part B uses calendar years, so your deductible resets every January 1.

After meeting your deductible, you typically pay 20% coinsurance for most Part B services, while Medicare pays the remaining 80%. There's no limit on this 20% coinsurance under Original Medicare, which is why many beneficiaries purchase Medigap supplemental insurance to cover these ongoing costs.

Understanding the 20% Coinsurance

Part B's 20% coinsurance can add up significantly, especially for expensive services or ongoing treatment of chronic conditions. For example, if you have a specialist visit with testing that Medicare approves for $500, you'll pay $100 after meeting your deductible. For more expensive services like certain cancer treatments or surgical procedures, that 20% can mean thousands of dollars in out-of-pocket costs.

The coinsurance applies to most Part B services, including doctor visits, diagnostic tests, durable medical equipment, and most therapies. However, certain preventive services are covered at 100% with no deductible or coinsurance if your provider accepts assignment and uses the correct billing codes.

Without supplemental coverage, you could face unlimited out-of-pocket spending under Part B. A serious illness requiring extensive treatment, multiple specialist visits, expensive tests, or ongoing therapies could result in tens of thousands of dollars in coinsurance costs. This unlimited exposure is why financial advisors often recommend Medigap coverage or Medicare Advantage plans with out-of-pocket maximums.

IRMAA: High-Income Surcharges Explained

Income-Related Monthly Adjustment Amounts (IRMAA) add surcharges to Part B premiums for higher-income Medicare beneficiaries. These surcharges are based on your modified adjusted gross income (MAGI) from your tax return from two years prior—so your 2025 IRMAA is based on your 2023 tax return.

For 2025, IRMAA brackets are: individuals with MAGI of $106,000 or less ($212,000 or less for joint filers) pay the standard $185 premium. Those earning $106,001-$133,000 ($212,001-$266,000 jointly) pay $259 monthly. Earners of $133,001-$167,000 ($266,001-$334,000 jointly) pay $370.90 monthly. Income of $167,001-$200,000 ($334,001-$400,000 jointly) results in $482.80 monthly premiums. Those earning $200,001-$500,000 ($400,001-$750,000 jointly) pay $594.70 monthly. The highest bracket, over $500,000 individually or $750,000 jointly, requires $628.90 monthly premiums.

IRMAA also applies to Part D premiums, adding $13.70 to $85.90 monthly depending on your income bracket. These surcharges are billed separately from your standard premiums and can significantly increase your Medicare costs if you have substantial retirement income from pensions, investments, or continued employment.

You can appeal your IRMAA determination if your income has decreased due to life-changing events like retirement, divorce, death of a spouse, or loss of income-producing property. File Form SSA-44 with Social Security to request a redetermination based on more recent income information.

Enrolling in Part B and Avoiding Penalties

Most people should enroll in Part B during their Initial Enrollment Period (IEP) when turning 65 unless they have credible group health coverage through current employment. If you delay Part B enrollment without qualifying coverage, you'll face a late enrollment penalty of 10% of the standard premium for each full 12-month period you were eligible but didn't enroll.

This penalty is permanent—it lasts as long as you have Part B coverage. For example, if you delay enrollment for three years without credible coverage, your monthly premium increases by 30% for life. With the 2025 standard premium of $185, that means paying an extra $55.50 monthly, or $666 annually, for the rest of your life.

Special Enrollment Periods allow penalty-free enrollment if you have group coverage through current employment (yours or your spouse's) with at least 20 employees. You can delay Part B while covered and enroll within eight months of that coverage ending without penalties. Always document your credible coverage carefully to prove you qualify for a Special Enrollment Period.

Getting Maximum Value from Part B

To maximize your Part B benefits, take full advantage of free preventive services. Annual wellness visits, cancer screenings, cardiovascular screening, diabetes testing, and vaccines are covered at no cost when properly coded and provided by participating providers. These services help detect and prevent serious health problems before they require expensive treatment.

Always verify that providers accept Medicare assignment, meaning they agree to accept Medicare's approved amount as full payment. Providers who don't accept assignment can charge up to 15% more than Medicare's approved amount, increasing your out-of-pocket costs significantly. You can search for participating providers on medicare.gov.

Consider supplemental coverage to protect against Part B's unlimited cost-sharing. Medigap Plan G is currently the most comprehensive option for new enrollees, covering Part B's deductible and 20% coinsurance. Medicare Advantage plans offer an alternative approach with networks and out-of-pocket maximums that cap your annual spending.

Understanding Part B coverage, costs, and strategies helps you make informed decisions about your healthcare and budget effectively for medical expenses throughout retirement. Despite the premiums and cost-sharing, Part B provides essential protection against the high costs of medical care.