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Medicare Part B: What It Covers, What It Costs, and What to Know Before You Enroll
How Part B Is Different from Part A — and Why That Distinction Matters
Part A covers care that requires admission to a hospital, skilled nursing facility, or hospice program. Part B picks up where Part A leaves off: it covers the ongoing, outpatient side of your health — the care that keeps you out of the hospital in the first place.
This distinction becomes important when you're reviewing an Explanation of Benefits, understanding a bill, or deciding whether a Medicare Supplement or Medicare Advantage plan is the right fit for your situation. Knowing which part of Medicare is responsible for a given service helps you understand your cost exposure and how additional coverage layers interact with your benefits.
It also matters at enrollment. Part A and Part B have separate enrollment rules, and the decisions you make about one don't automatically apply to the other. If you're still working when you turn 65, the timing of your Part B enrollment in particular deserves careful attention — enrolling too late can result in a permanent premium penalty.
Medicare is often described as a single program, but it's made up of distinct parts that each cover different things. Part A handles hospital stays and inpatient care. Part B is what covers the medical services most people use far more often — the appointments, the tests, the treatments that happen outside a hospital setting.
If you're approaching Medicare eligibility and wondering what Part B actually does for you, here's the straightforward version:
- Visits to your primary care doctor and specialists
- Outpatient procedures and same-day surgeries
- Preventive care, including annual wellness visits and many recommended screenings
- Lab work, X-rays, and diagnostic imaging ordered by your doctor
- Mental health services provided on an outpatient basis
- Durable medical equipment such as walkers, wheelchairs, and CPAP machines
- Certain home health services and outpatient physical, occupational, and speech therapy
- Some injectable and infused medications administered in a clinical setting
Part B generally covers 80% of approved costs after you meet the annual deductible. You're responsible for the remaining 20%, with no out-of-pocket cap unless you have a Medicare Supplement or Medicare Advantage plan that adds one.
Part B Is Where Most of Your Day-to-Day Medical Coverage Lives
What Part B Costs — and Why Your Premium May Be Higher Than You Expected
Most people are aware that Medicare Part B comes with a monthly premium. For 2026, the standard premium is $202.90 per month. But a meaningful number of people pay more than that — and many are surprised to find out why.
The reason is something called the Income-Related Monthly Adjustment Amount, or IRMAA. If your income from two years prior exceeded a certain threshold, Medicare adjusts your Part B premium upward on a sliding scale. The adjustment is based on your Modified Adjusted Gross Income (MAGI) as reported on your federal tax return.
For 2026, IRMAA applies to individuals with income above $109,000 and married couples filing jointly with income above $218,000. The surcharge is paid directly to Medicare, separate from any plan premium you may also be paying.
If your income has decreased significantly since the reference year — due to retirement, loss of a spouse, or another qualifying life event — you may be able to request a reconsideration from Social Security. This is a step many people don't know is available to them, and it can make a real difference in what you actually pay each month.
Beyond IRMAA, Part B also comes with an annual deductible and a 20% coinsurance on most covered services after that deductible is met. That 20% has no cap under Original Medicare alone, which is one of the primary reasons many people pair Part B with either a Medicare Supplement (Medigap) plan or a Medicare Advantage plan — both of which are designed to limit your out-of-pocket exposure.
Part B Enrollment: Timing Is Everything
Enrollment in Part B is not automatic for everyone, and missing your window can have lasting financial consequences. Understanding when to enroll — and when it may be appropriate to delay — is one of the most important decisions you'll make when you first become Medicare-eligible.
Initial Enrollment Period (IEP): Your IEP spans seven months — the three months before your 65th birthday month, your birthday month itself, and the three months after. This is your primary window to enroll in Part B without penalty.
Special Enrollment Period (SEP): If you're covered by employer-sponsored health insurance through your own active employment (or your spouse's) when you turn 65, you may be eligible to delay Part B without penalty. Once that employer coverage ends, you have an eight-month Special Enrollment Period to sign up.
Late Enrollment Penalty: If you miss your IEP and don't qualify for an SEP, you may face a late enrollment penalty — a 10% increase added to your Part B premium for each full 12-month period you went without coverage. This penalty is permanent and applies for as long as you have Part B.
The rules around employer coverage, COBRA, retiree coverage, and marketplace plans can create real confusion about whether delaying Part B is the right call. If you're still working and navigating this decision, the Medicare While Still Working page walks through the key considerations in detail.
What Clients Say
Questions We Hear Most About Medicare Part B
What does Medicare Part B cover that Part A doesn't?
Part B covers outpatient medical services — doctor visits, specialist appointments, preventive screenings, lab work, diagnostic imaging, durable medical equipment, and most care you receive outside of a hospital stay. Part A covers inpatient hospital care, skilled nursing facility stays, hospice, and some home health services. The two parts are designed to work together, but they cover distinct categories of care.Part B covers outpatient medical services — doctor visits, specialist appointments, preventive screenings, lab work, diagnostic imaging, durable medical equipment, and most care you receive outside of a hospital stay. Part A covers inpatient hospital care, skilled nursing facility stays, hospice, and some home health services. The two parts are designed to work together, but they cover distinct categories of care.Why is my Medicare Part B premium higher than the standard amount?
If your income from two years ago exceeded a certain threshold, Medicare applies an Income-Related Monthly Adjustment Amount (IRMAA) that increases your Part B premium. The adjustment is based on your Modified Adjusted Gross Income from your federal tax return. If your income has since dropped due to retirement or another qualifying life event, you may be able to request a reassessment through Social Security using Form SSA-44.If your income from two years ago exceeded a certain threshold, Medicare applies an Income-Related Monthly Adjustment Amount (IRMAA) that increases your Part B premium. The adjustment is based on your Modified Adjusted Gross Income from your federal tax return. If your income has since dropped due to retirement or another qualifying life event, you may be able to request a reassessment through Social Security using Form SSA-44.Can I delay Part B enrollment if I'm still working?
Yes, in many cases. If you have health coverage through your own active employment or your spouse's active employment when you turn 65, you may be eligible to delay Part B enrollment without incurring a late penalty. Coverage through COBRA, retiree plans, or the ACA marketplace generally does not qualify for this exception. Because the rules involve several variables, it's worth reviewing your specific situation before making a decision.Yes, in many cases. If you have health coverage through your own active employment or your spouse's active employment when you turn 65, you may be eligible to delay Part B enrollment without incurring a late penalty. Coverage through COBRA, retiree plans, or the ACA marketplace generally does not qualify for this exception. Because the rules involve several variables, it's worth reviewing your specific situation before making a decision.What is the Part B late enrollment penalty and how long does it last?
The late enrollment penalty adds 10% to your Part B premium for each full 12-month period you were eligible for Part B but didn't enroll and didn't have qualifying coverage. This increase is permanent — it stays with you for as long as you have Part B. Avoiding it requires either enrolling during your Initial Enrollment Period or qualifying for a Special Enrollment Period through employer coverage.The late enrollment penalty adds 10% to your Part B premium for each full 12-month period you were eligible for Part B but didn't enroll and didn't have qualifying coverage. This increase is permanent — it stays with you for as long as you have Part B. Avoiding it requires either enrolling during your Initial Enrollment Period or qualifying for a Special Enrollment Period through employer coverage.Does Medicare Part B cover prescription drugs?
Part B covers a limited category of drugs — primarily medications that are administered in a clinical setting, such as infusions, injections given at a doctor's office, and certain chemotherapy drugs. It does not cover most retail prescriptions you pick up at a pharmacy. For that coverage, you would need a Medicare Part D plan or a Medicare Advantage plan that includes drug benefits.Part B covers a limited category of drugs — primarily medications that are administered in a clinical setting, such as infusions, injections given at a doctor's office, and certain chemotherapy drugs. It does not cover most retail prescriptions you pick up at a pharmacy. For that coverage, you would need a Medicare Part D plan or a Medicare Advantage plan that includes drug benefits.
We Help You Sort Through Part B Before You Commit to Anything
Medicare Part B decisions — when to enroll, how to respond to an IRMAA notice, how your premium interacts with the rest of your coverage — have real financial consequences that can follow you for years. Our team has been helping Washington residents work through exactly these questions for more than two decades.
We don't rush the conversation. We take the time to understand your income situation, your current coverage, and your timeline so you can make a decision that actually fits your life. If your Part B premium came in higher than you expected, or if you're trying to figure out the right time to enroll, we're glad to walk through it with you.