Start with two questions: how will your medical care be covered, and how will your prescriptions be covered? The letters describe different pieces of that answer. They are not four plans that everyone must buy.
What each part does
| Part | Main role | What to remember |
|---|---|---|
| A | Inpatient hospital, eligible skilled nursing, hospice and some home health care. | Coverage conditions and cost sharing still apply. |
| B | Doctors, outpatient care, medically necessary supplies and preventive services. | A monthly premium is separate from what you pay for services. |
| C | Medicare Advantage, a private-plan way to receive your Medicare benefits. | You still need Parts A and B. Most plans include drug coverage. |
| D | Prescription drug coverage through private Medicare plans. | Covered drugs, pharmacies and costs depend on the plan. |
Put the pieces together
With Original Medicare, Parts A and B handle your medical coverage. You can add a separate Part D plan and consider a Medigap policy to help with eligible medical cost sharing. With Medicare Advantage, your plan administers your medical benefits and usually your drug benefits. Medigap does not pay Medicare Advantage cost sharing.
A hospital visit can involve more than one part
Being in a hospital bed overnight does not by itself make you an inpatient. Observation services can be outpatient care. Your formal admission status affects which benefits apply and can affect later skilled nursing coverage. Ask the hospital about your status instead of assuming that every hospital charge falls under Part A.
What the letters do not promise
Medicare is not a promise that every health expense is covered. Long-term custodial care and many routine dental, hearing and vision expenses fall outside Original Medicare. An extra benefit in a private plan may have its own limits. Look at the service, the setting and the coverage terms.
Your first planning page
- List your current medical and prescription coverage separately.
- Write down the start dates shown for Parts A and B, if you already have a Medicare card.
- List the doctors and medicines you want to check.
- Compare both coverage routes before focusing on a plan premium.
Common question: Is Medigap Plan G the same as a Medicare part? No. A Medigap letter identifies a supplemental policy design, not a new part of Medicare.
Follow one episode of care
Imagine a person visits a specialist, has an outpatient test and later enters the hospital as an inpatient. Those are connected medically, but they are not necessarily one insurance charge. Professional services, outpatient facility services and inpatient facility care can be processed under different benefits. Ask for an estimate that identifies the setting and who will bill, rather than asking only whether the diagnosis is covered.
A prescription also needs context. Some drugs administered as part of treatment are handled under Part B, while many medicines filled at a pharmacy are handled under Part D. The drug’s name alone may not tell you which benefit applies. Ask the provider or pharmacy which benefit it is billing and whether any approval is needed.
Medicare is individual coverage
A couple can choose different arrangements because their providers, medicines and preferences differ. A spouse who is not eligible for Medicare does not become covered by the other spouse’s enrollment. When leaving a family policy, make a separate coverage plan for every person on it.
A few common mix-ups
- Is Medicare the same as Medicaid?
- No. Medicare is a federal health insurance program with its own eligibility rules. Medicaid is a state-administered assistance program with different requirements. Some people have both.
- Does a Medicare card prove I have Part D?
- No. Review drug-plan enrollment separately and keep the appropriate plan card for pharmacy use.
- Does Part A cover a long nursing-home stay?
- Do not equate limited skilled nursing benefits with ongoing custodial care. The type of care and coverage criteria matter, not simply the building’s name.
Sources and update notes
Published by My Coverage Relay. Updated September 24, 2026. This guide explains general rules; individual eligibility, plan terms and state protections require a specific review.