Medicare Part B, doctor and outpatient coverage

The list is broad, which is the point. Part B is the everyday-medicine part of Medicare:

• Doctor visits: primary care and specialists.
• Outpatient care: procedures and surgeries that do not require an admission.
• Preventive services: many screenings, an annual wellness visit, and most vaccines.
• Lab tests and imaging: bloodwork, X-rays, scans.
• Durable medical equipment: wheelchairs, oxygen, diabetic supplies, and similar.
• Some limited prescription drugs: generally those administered in a clinical setting, like infusions, rather than what you pick up at a pharmacy.

Preventive care is often free, but not always. Medicare covers many preventive services at no cost to you, no deductible, no coinsurance, when you see a provider who accepts assignment: the annual "wellness visit," many cancer screenings, a yearly flu shot, and more. The catch: a free screening can turn into a billed service in the same visit. If a screening colonoscopy finds and removes a polyp, the procedure can shift from "preventive" to "diagnostic" and cost-sharing can apply. It is a coding distinction, not a trick, but it surprises people who walked in expecting "free."

The Welcome to Medicare visit. In your first 12 months on Part B, you are entitled to a one-time "Welcome to Medicare" preventive visit, a baseline review of your health, risk factors, and the screenings you are due for. It is genuinely useful and frequently skipped simply because no one mentions it.

Durable medical equipment. Part B covers equipment your doctor prescribes for use at home, wheelchairs, walkers, hospital beds, oxygen, CPAP machines, blood-sugar monitors. You generally pay 20 percent after the deductible, and the equipment usually has to come from a supplier enrolled with Medicare.

Drugs, but only some. Part B covers drugs administered to you in a clinical setting, an infusion in an oncologist's office, a vaccine, certain injectables. The medications you fill at a pharmacy are Part D's job. The line is "who administers it," and it confuses people whose expensive drug happens to fall on one side or the other.

Now the part that shapes every other Medicare decision you will make. After you meet a modest annual deductible of $283 in 2026, Part B generally pays 80% of the approved cost of your care. You pay the other 20%.

That 20% sounds manageable, and for a routine year it is. The problem is what the sentence leaves out: there is no annual cap on it. Twenty percent of an ordinary year is small. Twenty percent of a serious year, a major surgery, a cancer course, a long hospital-and-rehab sequence, has no ceiling. The bill keeps going.

This single design feature, an open-ended 20%, is the reason the rest of the Medicare market exists. It is why most people on Original Medicare add a Medigap supplement to cover that share. It is also why Medicare Advantage, which does include an annual out-of-pocket maximum, appeals to people who would rather have a defined worst case. You cannot really evaluate either option until you understand the gap they are both responding to.

Here is a wrinkle that rarely gets explained and occasionally costs real money. Most providers "accept assignment," meaning they agree to Medicare's approved amount as full payment. You owe your 20 percent and nothing more. This is the common case, and it is why most people never think about it.

A smaller group are "non-participating" providers. They still take Medicare, but they have not agreed to the approved amount, and they are allowed to bill you up to a set percentage above it, an "excess charge." On a routine visit this is trivial. On an expensive procedure it is not, and it is exactly the kind of thing worth asking about in advance.

A few states prohibit excess charges entirely, so this never comes up for residents there. And one Medigap detail connects here: some supplement plans cover excess charges and some do not, which is one of the small differences between Medigap plan letters. None of this is a reason for alarm; it is a reason to ask "do you accept Medicare assignment?" before a big-ticket service.

Most people should take Part B as soon as they are eligible at 65, because delaying it without a good reason triggers a permanent penalty (covered in its own article). There is one common exception worth stating clearly: if you are still working at 65 and have coverage through an employer with 20 or more employees, you can usually delay Part B without penalty and enroll later through a Special Enrollment Period.

The traps in that exception are specific. Coverage from a smaller employer often does not protect you the same way, because Medicare typically becomes the primary payer at 65 regardless of what the group plan says, meaning your employer plan may pay little and leave you exposed. And COBRA or retiree coverage does not count as the kind of active employer coverage that protects your enrollment window. These are exactly the situations where a short conversation before you decide is worth more than a correction afterward, because the penalty for getting it wrong is permanent.

Part B is medical insurance, not drug insurance. The prescriptions you fill at a pharmacy are Part D's job. Routine dental, vision, and hearing are mostly outside Original Medicare altogether, with narrow exceptions, such as an eye exam tied to a medical condition like diabetes, or dental work that is an inseparable part of a covered surgery. Knowing where Part B stops is how you figure out what else, if anything, you need to add, whether that is a Part D plan, a Medigap supplement to handle the 20 percent, or a Medicare Advantage plan that bundles extras in.