Medicare at the outset seems to be simple and straightforward. One needs to understand the nuances and ask "who pays for what" at all junctures. There is a concept of Medigap which can be purchased in addition to Part B and Part D (Part A is a core part of Medicare).
The Four Parts of Medicare
Part A — Hospital Insurance
Covers hospital room, meals, nursing care, inpatient services & supplies. (The Building)
Part B — Medical Insurance
Covers doctors, specialists, surgeons, diagnostic tests, MRIs, labs & anesthesia. (The People)
Part D — Prescription Drugs
Standalone prescription drug coverage added on top of Original Medicare.
Part C — Medicare Advantage
Private plans that bundle Part A + Part B (and often Part D) into one plan.
When You Go to the Hospital
The key question is: How are you classified? This classification dramatically affects your costs and future coverage.
✅ Admitted (Inpatient)
Doctor decides you need inpatient care. Covered under Part A for the hospital stay and Part B for doctors/services.⚠️ Not Admitted (Observation / Outpatient)
You are treated but not admitted as inpatient. Everything billed under Part B only — you pay 20% of all approved services (no Part A).What You Pay Without Medigap
Part A Costs
- Deductible per benefit period (~$1,632 in 2024)
- Coinsurance after deductible
- Amounts vary based on length of stay
Part B Costs
- Monthly Part B premium
- Annual deductible (~$240 in 2024)
- 20% coinsurance on ALL approved Part B services — no cap
Observation / Outpatient Costs (No Medigap)
- Monthly Part B premium + annual deductible
- 20% coinsurance on ALL approved services — no cap
- Can be very expensive, especially for long observation stays
Do You Have a Medigap (Medicare Supplement) Plan?
Medigap is purchased in addition to Original Medicare to fill the coverage gaps — deductibles, coinsurance, and copays.
▶ For Inpatient Admission:
✅ With Medigap — Medigap Pays the Gaps
- Part A deductible
- Part A & B coinsurance / copays
- Blood (Part A deductible)
- Hospice coinsurance/copays
- Foreign travel emergency (Plans C, D, F, G, M, N only)
Your out-of-pocket = little or nothing for covered services
❌ Without Medigap — You Pay the Gaps
- Part A deductible
- Part A & B coinsurance
- Blood deductible
- Hospice coinsurance / copays
- Can be thousands of dollars
Your out-of-pocket = potentially very high
▶ For Observation / Outpatient Stay:
✅ With Medigap — Medigap Pays the Gaps
- Part B 20% coinsurance
- Part B deductible
Your out-of-pocket = little or nothing for covered services
❌ Without Medigap — You Pay the Gaps
- 20% of ALL approved Part B services — no cap
- Can be very expensive, especially for long observation stays
Your out-of-pocket = potentially very high
After Hospital Discharge
After Inpatient Stay
To qualify for Skilled Nursing Facility (SNF) care under Part A:- Must have a 3-day inpatient stay (3 midnights)
- SNF care is covered (limited days)
- Home health care may be covered
After Observation Stay
Does NOT qualify for SNF care under Part A (because there was no 3-day inpatient stay).You may be responsible for the full cost of rehab or extended care.
Important Notes
Observation vs Inpatient: Classification can significantly affect your out-of-pocket costs and future coverage. Always ask your care team about your status (inpatient vs observation) and estimated costs.
Part B 20% Coinsurance: Part B has 20% coinsurance with no out-of-pocket maximum. Without Medigap, you are exposed to unlimited financial risk.
"Benefit Period" for Part A: Starts the day you are admitted as an inpatient and ends when you have been out of the hospital for 60 consecutive days.
What Medigap Does NOT Cover: Prescription drugs, long-term care, dental, vision, or hearing aids. These require separate coverage (Part D, etc.).
Key Takeaway
Part A (The Building — Hospital Stay) +
Part B (The People — Doctors & Medical Services) +
Medigap (The Filler — Pays the Gaps)
= Financial Protection & Peace of Mind
This is how Original Medicare and Medigap work together in a hospitalization scenario.
= Financial Protection & Peace of Mind
This is how Original Medicare and Medigap work together in a hospitalization scenario.