Medicare 101
The ABCs of Medicare: Your Complete 101 Guide
Understanding how Medicare works doesn't have to be complicated. Here is a clear breakdown of Parts A, B, C, and D, supplement options, and eligibility guidelines.
What Is Medicare?
Medicare is the federal health insurance program for people age 65 or older, certain younger people with disabilities, and people with End-Stage Renal Disease (ESRD). It is administered by the Centers for Medicare & Medicaid Services (CMS) and is divided into distinct parts, each covering different types of care.
Understanding how each part works — and how they fit together — is the first step toward choosing coverage that protects your health and your finances.
Explaining the Four Parts of Medicare
Medicare is divided into four parts, each covering a different category of care.
Part A
Hospital Insurance
What it Covers
Inpatient hospital stays, skilled nursing facility care, hospice care, and limited home health services.
Cost
Most beneficiaries receive Premium-Free Part A if they or their spouse paid Medicare taxes for at least 10 years (40 quarters). Deductibles and copays apply per benefit period.
Part B
Medical Insurance
What it Covers
Doctor visits, outpatient medical services, preventive care, lab tests, durable medical equipment (DME), and mental health services.
Cost
Requires a standard monthly premium. After meeting the annual deductible, Original Medicare typically pays 80% of approved amounts, leaving you responsible for the remaining 20%.
Part C
Medicare Advantage
What it Covers
An all-in-one private insurance alternative to Original Medicare. Bundles Part A and Part B, usually includes Part D prescription drug coverage, and often adds extra benefits like dental, vision, hearing, and wellness programs.
Cost & Structure
Plans use local networks (HMOs or PPOs) and have set copays, coinsurance, and out-of-pocket maximum caps.
Part D
Prescription Drug Coverage
What it Covers
Standalone prescription drug coverage provided through private insurance companies approved by Medicare.
Cost & Structure
Each plan has a specific formulary (tier list of covered drugs). Benefits include annual out-of-pocket spending limits to keep drug costs manageable.
Medicare Supplement Plans (Medigap)
How It Works
Optional coverage sold by private carriers designed to work alongside Original Medicare (Parts A and B).
Key Feature
Helps pay remaining out-of-pocket gaps such as the 20% Part B coinsurance, copayments, and hospital deductibles.
Flexibility
Allows you to visit any doctor or hospital nationwide that accepts Original Medicare without network limitations or referral requirements.
Eligibility Rules
You qualify for Medicare if you meet any of the following criteria:
Age 65+
You are a U.S. citizen or legal permanent resident (living in the U.S. continuously for at least 5 years) turning 65.
Disability (Under 65)
You have received Social Security Disability Insurance (SSDI) benefits for at least 24 consecutive months.
Qualifying Medical Conditions
You have been diagnosed with End-Stage Renal Disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS / Lou Gehrig's disease).
Essential Enrollment Deadlines
Missing an enrollment window can result in permanent late enrollment penalties and gaps in coverage. Here are the most important periods to know.
Initial Enrollment Period (IEP)
7 monthsA 7-month window starting 3 months before the month you turn 65, including your birth month, and ending 3 months after.
Annual Enrollment Period (AEP)
Oct 15 – Dec 7Every year from October 15 to December 7, allowing you to join, switch, or drop Medicare Advantage or Part D plans.
Late Enrollment Penalties
PermanentEnrolling late for Part B or Part D without creditable coverage may lead to lifelong monthly premium penalties.
Not Sure Where to Start?
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