Medicare can sometimes feel like learning a new language. Understanding the words and phrases used in letters, TV ads, and plan brochures helps you make confident choices. Here’s an easy-to-follow guide to help you know the most common Medicare terms – and a few that even seasoned members sometimes confuse.
Basic Terms
Medicare
The federal health insurance program for people age 65 and older, and for some younger people with disabilities or certain medical conditions.
Original Medicare
The government’s standard coverage is made up of Part A (hospital insurance) and Part B (medical insurance). You can add Part D (prescription coverage) and/or a Medigap plan for extra protection.
Medicare Advantage (Part C)
Private plans approved by Medicare that bundle hospital, medical, and often drug coverage together. Many also include dental, vision, hearing, or fitness benefits.
Medigap (Supplemental Insurance)
Private insurance that helps pay for costs Original Medicare doesn’t cover, such as copayments and deductibles. These plans are labeled with letters (Plan G, Plan N, etc.).
Costs and Payments
Premium
The amount you pay each month for your coverage.
Deductible
The amount you pay each year before your plan begins to share the cost.
Copayment (Copay)
A fixed dollar amount you pay for a service, like $20 for a doctor’s visit.
Coinsurance
A percentage of the cost you pay after meeting your deductible – for example, 20% of the bill.
Out-of-Pocket Maximum
The most you’ll pay for covered services in a year. After you reach it, your plan pays 100% of approved costs.
Balance Billing
When a provider bills you for the difference between their charge and what Medicare approves, it can be confusing. This can happen if you use non-participating doctors.
Late Enrollment Penalty
An extra cost is added to your monthly premium if you don’t sign up for Part B or Part D when first eligible and don’t qualify for special enrollment.
Enrollment and Plan Changes
Initial Enrollment Period (IEP)
The seven-month window around your 65th birthday to sign up for Medicare.
General Enrollment Period (GEP)
From January 1 to March 31 each year, this applies to those who missed initial enrollment.
Annual Election Period (AEP)
From October 15 to December 7 each year, you can join, switch, or drop Medicare Advantage or Part D plans.
Special Enrollment Period (SEP)
A time outside the regular windows when you can enroll or make changes due to certain life events, such as losing other coverage or moving to a new area.
Guaranteed Issue Rights
Protections allowing you to buy a Medigap policy without being denied or charged more due to health history, usually after losing other coverage.
Coverage and Services
In-Network Provider
Doctors, hospitals, or pharmacies that contract with your plan and offer lower costs.
Out-of-Network Provider
Medical professionals not contracted with your plan may cost more or be uncovered.
Formulary
The list of drugs covered by a Medicare drug or Advantage plan, organized by “tiers” that affect cost.
Prior Authorization
When your plan requires approval for a service or prescription before it’s covered.
Referral
A written order from your primary care doctor allowing you to see a specialist.
Preventive Services
Screenings, vaccines, and checkups aimed at preventing illness or detecting problems early – often covered at no cost.
Durable Medical Equipment (DME)
Reusable medical items like wheelchairs, oxygen equipment, and blood-sugar monitors.
Skilled Nursing Facility (SNF)
A facility providing round-the-clock medical or rehabilitation care after a hospital stay. Medicare Part A covers a limited stay if requirements are met.
Home Health Care
Medically necessary services are provided at home under a doctor’s supervision.
Hospice Care
End-of-life comfort care for those with a terminal illness is covered under Part A.
Prescription Coverage Terms
Part D
Medicare’s prescription drug coverage is offered through private insurers.
Coverage Gap (Donut Hole)
A temporary limit on what your plan pays for medications after you and your plan have spent a certain amount. After reaching “catastrophic coverage,” your cost drops significantly.
Catastrophic Coverage
The final phase of Part D coverage is where your costs are significantly reduced for the rest of the year.
Tier Levels
Groups of drugs organized by cost. Tier 1 drugs are usually generic and the lowest cost; Tier 4 or 5 are specialty medications and the most expensive.
Network Pharmacy
A pharmacy contracted with your plan. Using one helps you pay less.
Mail-Order Pharmacy
A service that delivers medications to your home, often at a lower cost for a 90-day supply.
Documents and Communication
Explanation of Benefits (EOB)
A summary from your plan showing what was billed, what Medicare paid, and what you owe. It’s not a bill, but it helps you track spending.
Medicare Summary Notice (MSN)
A quarterly statement is sent to people with Original Medicare summarizing services and costs.
Advance Beneficiary Notice (ABN)
A notice from a provider that Medicare may not pay for a service, giving you the option to decline it or agree to pay out-of-pocket.
Fraud and Protection
Medicare Number
Your unique ID used for billing and coverage — never share it except with trusted providers.
Medicare Fraud
When someone bills for services you didn’t receive or uses your number illegally. Report suspected fraud at 1-800-MEDICARE.
Coordination of Benefits (COB)
Determines which insurance pays first when you have multiple coverages (for example, employer insurance and Medicare).
Helpful Tip
Keep a notebook or folder of your plan documents, prescription list, and doctor information. Understanding these terms helps you compare plans and avoid surprises in medical bills.