If Medicare Part A is the hospital half of Original Medicare, Part B is the medical half. Together, they form the foundation of coverage for millions of Americans, but they apply to different types of care. Understanding how the two fit together can help you anticipate costs, avoid coverage surprises, and make more informed decisions as retirement approaches.
Part A and Part B: Two Pieces of the Same Puzzle
Medicare Part A generally helps cover inpatient hospital stays, limited care in a skilled nursing facility, hospice care, and certain home health services. Part B generally covers the medical services that surround that care, including physician visits, outpatient procedures, diagnostic tests, ambulance services, therapy, durable medical equipment, and many preventive services.
Consider someone who experiences a heart event. Part A may help cover the hospital stay after the patient is formally admitted. Part B may cover the cardiologist’s professional services, follow-up appointments, outpatient cardiac rehabilitation, testing, and certain medical equipment.1 The two parts are designed to complement one another, not duplicate coverage.
A practical way to frame the distinction is:
Medicare component | Primary role | Typical examples |
Part A | Inpatient and facility-based care | Hospital admission, limited skilled-nursing-facility care, hospice, certain home health care |
Part B | Physician, outpatient, and preventive care | Office visits, specialist care, outpatient surgery, tests, therapy, medical equipment, preventive services |
One detail can make a meaningful difference: receiving care at a hospital does not necessarily mean it falls under Part A. If you are treated as an outpatient or kept under observation without being formally admitted, the services may be billed under Part B. When in doubt, ask about your admission status and how the care will be billed.
What Does Part B Cost?
Part A is premium-free for most people who have sufficient Medicare-covered work history (typically at least 10 years of Medicare-taxed employment). Part B is voluntary, but it requires a monthly premium.2 Part B also generally involves:
- An annual deductible
- Usually 20% coinsurance of the Medicare-approved amount for many covered services after the deductible
- Potential additional exposure if using a provider who does not accept Medicare assignment
While the 20% coinsurance can be manageable for routine care, larger or recurring expenses may add up. Original Medicare does not include a general annual out-of-pocket maximum. Some beneficiaries address that exposure with a Medicare Supplement Insurance, or Medigap, policy and separate Part D prescription drug coverage. Others choose a Medicare Advantage plan, which provides Part A and Part B benefits through a private insurer and may include drug coverage and other benefits. Each route has different costs, networks, and tradeoffs.
One detail can make a meaningful difference: receiving care at a hospital does not necessarily mean it falls under Part A.
Timing Matters
For most people, the Initial Enrollment Period begins three months before the month they turn 65 and ends three months after it. Delaying Part B without qualifying coverage may result in a lasting late-enrollment penalty. The rules can be different for people who are still working and covered through a current employer, so it is wise to review your options before assuming you can postpone enrollment.
The upcoming Medicare Open Enrollment Period, October 15 through December 7, serves a different purpose.3 It is not the initial enrollment window for Part B. Instead, it allows current Medicare beneficiaries to review and change Medicare Advantage or Part D coverage for the following year. Changes generally take effect January 1.
Even if you are comfortable with your current plan, review its Annual Notice of Change. Premiums, deductibles, drug formularies, pharmacy networks, provider networks, and benefits can change from year to year. A plan that worked well this year may not be the best fit next year.
Make Medicare Part of the Bigger Picture
Medicare decisions do not happen in isolation. Premiums, income-related surcharges, prescription coverage, supplemental insurance, and expected out-of-pocket costs can all affect your retirement income plan. The goal is not simply to choose coverage, but to understand how that choice supports your health needs and broader financial strategy.
If you have questions about Medicare Part B, the upcoming Open Enrollment Period, or how healthcare costs fit into your retirement plan, talk with your financial advisor. We can help you evaluate the financial implications, identify questions to ask, and connect your healthcare choices to the retirement goals you’re building towards.