Part One: A Quick Primer on How Medicare Is Structured
Before we get into the gaps, it helps to understand what Medicare actually consists of. Many retirees are surprised to learn that Medicare is not a single program — it is a collection of parts, each covering a different category of care.
| Medicare Part | What It Covers | Monthly Premium | Key Gap |
| Part A | Hospital stays, skilled nursing, hospice, and some home health | Usually $0 (if you worked 10+ years) | Custodial nursing home care after 100 days |
| Part B | Doctor visits, outpatient care, preventive services, and medical equipment | $185.00/month in 2026 | Dental, vision, hearing — not covered |
| Part C (Medicare Advantage) | Bundles A + B + often D, may add dental/vision/hearing | Varies by plan ($0 to $100+) | Network restrictions, prior authorization |
| Part D | Prescription drug coverage (through private plans) | Varies by plan (avg. ~$46/month) | Coverage gap (donut hole) still exists for some drugs |
If you have Original Medicare (Parts A and B only), you are exposed to nearly all of the gaps described below. Parts C and D—and supplemental insurance products like Medigap—exist specifically to address those exposures.
