Medicare

Medicare Parts A, B, C & D Explained: What Each Part Covers

Published October 21, 2026 · 7 min read · Figures last verified October 21, 2026

Reviewed by D.P., PharmD.

Medicare is the federal health insurance program for people 65 and older (and some younger people with disabilities). The confusing part is the alphabet: A, B, C, D. Here's what each letter actually pays for, what it costs, and how the pieces fit together.

The four parts at a glance

Part A: hospital insurance

Part A covers inpatient hospital care, you're formally admitted, plus short stays in skilled nursing facilities, hospice care, and some home health services. Think of it as the building and the bed, it pays for overnight stays.

There's no monthly premium for about 99% of beneficiaries, you or your spouse paid Medicare taxes for at least 40 quarters (roughly 10 years), per CMS. Short of that, you can buy in: $565 per month in 2026 for fewer than 30 quarters, $311 per month for 30 to 39. But "no premium" doesn't mean "no cost." Part A carries Medicare's biggest single deductible: $1,736 per hospital stay in 2026, and it applies per benefit period, not per year. A benefit period ends after you've been out of the hospital or skilled nursing for 60 straight days; get readmitted after that, and you owe the $1,736 again. That's the quirk that surprises people with repeat hospital bills. Longer stays add daily coinsurance: $434/day for hospital days 61 to 90, $868/day for lifetime reserve days, and $217/day for skilled nursing days 21 to 100.

Part B: medical insurance

Part B is the everything-else part: doctor visits, outpatient care, labs, X-rays, medical equipment, and preventive services like flu shots. If Part A is the hospital bed, Part B is the doctors who treat you. Unlike Part A it always has a premium: the standard amount is $202.90 per month in 2026, with a $283 annual deductible, then typically 20% of the Medicare-approved amount for most services.

Higher earners pay more: if your income from two years earlier exceeds $109,000 (single) or $218,000 (married filing jointly), an income-related surcharge lifts the Part B premium to somewhere between $284.10 and $689.90 per month in 2026, and the same income test adds a surcharge to Part D. Also know that Part B isn't automatic: skip your initial enrollment window without a qualifying exception and a late-enrollment penalty adds 10% to your premium for every full year you were eligible but didn't sign up, permanently.

The surprise hiding in Part B: diabetes supplies. Most people assume everything diabetes-related sits in the drug plan. It doesn't. Part B covers blood glucose monitors, test strips and lancets (up to 300 of each every 3 months if you use insulin, 100 if you don't), continuous glucose monitors if you use insulin or have a history of problematic low blood sugar, and even therapeutic shoes for diabetic foot disease. It also covers insulin pumps as medical equipment, and the insulin used in the pump. That pump insulin costs no more than $35 for a one-month supply, and the Part B deductible doesn't apply to it. Insulin you inject with a pen or syringe is the Part D version, also capped at $35 a month per insulin product. Same hormone, two different parts, depending on how it gets into you. (Full guide coming: which part pays for each diabetes item.)

Part C: Medicare Advantage, the private-plan alternative

Part C isn't an extra on top of A and B, it's a different way to receive the same benefits. A private insurance company bundles A and B into one plan; most plans also include Part D drug coverage and add extras Original Medicare doesn't cover, like dental, vision, and hearing.

The trade: private plans use provider networks (you usually pay more, or get nothing, for out-of-network care), and nearly all require prior authorization for some services, the plan must approve care before you get it. Our guides on prior authorization timelines and step therapy describe exactly these managed-care mechanics.

Cost-wise, you still pay your Part B premium, but the plan's own premium is often $0 per month: about three-quarters of individual Medicare Advantage drug-plan enrollees pay nothing beyond the Part B premium, per KFF. In 2026, 55% of eligible Medicare beneficiaries are in Medicare Advantage plans, up from 19% in 2007 (KFF), the more common choice now, but still a choice, not the default.

Part D: prescription drug coverage

Part D is Medicare's drug plan. Original Medicare (Parts A and B) does not cover most prescription drugs you take at home, on the Original Medicare track you need a separate standalone Part D plan. (Most Medicare Advantage plans bundle drug coverage in.)

The 2026 standard benefit: you pay the first $615 (the annual deductible), then 25% of your drug costs until your out-of-pocket spending reaches $2,100. After that, you pay $0 for covered drugs the rest of the year, the catastrophic phase. The old "donut hole" coverage gap is gone; the $2,100 cap replaced it. Part D plans can also use prior authorization, step therapy, and quantity limits on individual drugs.

Important: Part D has its own late-enrollment penalty, about 1% of the national base premium for each month you were eligible but didn't enroll without other drug coverage, added to your premium permanently. If you don't need drugs today, "I'll sign up later" still costs money.

The two tracks: pick one

Here's the decision the four parts add up to:

• Original Medicare = Part A + Part B from the government, plus a standalone Part D plan for drugs. Any doctor who accepts Medicare; many people add a Medigap policy for the deductibles and 20% coinsurance.
• Medicare Advantage = one Part C plan from a private company replacing A+B, usually with D bundled. One card, one network, extras like dental, with network and prior-authorization rules.

Compare on total yearly cost, premium × 12 plus deductibles and copays for the care and drugs you actually use, not the monthly premium alone. Medicare's official tool, Plan Compare at medicare.gov, takes your drugs and pharmacy and shows total estimated costs; we don't host our own estimator, the official tool has the current numbers. For free one-on-one help, your state's SHIP program offers unbiased counseling.

What's next

This overview starts our Medicare series. Next: comparing plans on total cost during open enrollment, the Part D out-of-pocket cap, and a Plan Compare walkthrough.

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