The Plain-English
Medicare Glossary

The federal health insurance program for people 65 and older, plus people under 65 with certain disabilities or End-Stage Renal Disease. It's run by the Centers for Medicare & Medicaid Services (CMS), not by an insurance company.

The federal agency that runs Medicare and Medicaid. They make the rules, set the payment rates, and review the insurance products that carriers sell as Medicare Advantage and Part D plans.

Part A and Part B together — the government's version of Medicare, without any extra insurance company in the middle. It covers a lot but not everything, and there's no annual out-of-pocket maximum, which is why most people add either a Medicare Supplement or switch to a Medicare Advantage plan.

You're Medicare-eligible if you're 65 or older, or if you're under 65 and have received Social Security Disability payments for 24 months or have End-Stage Renal Disease or ALS.

Covers inpatient hospital stays, skilled nursing facility stays, hospice care, and some home health. Most people pay $0 premium for Part A because they (or a spouse) paid Medicare taxes while working.

Covers doctor visits, outpatient care, preventive services, lab work, durable medical equipment (wheelchairs, CPAP machines), and most of what isn't hospitalization. Part B has a monthly premium that all Medicare-eligible individuals pay. The premium is deducted from your Social Security check before you receive any funds — so you don't have to send a payment to Medicare each month. The Part B premium goes up each year. For 2026, the base premium is $202.90, but it can go up based on your annual income.

An all-in-one plan sold by private insurance companies that replaces Original Medicare. It includes Parts A and B, usually Part D (prescription drugs), and often extras like dental, vision, hearing, OTC credits, and a gym benefit. You still have Medicare — you're just receiving it through a private plan that CMS pays to manage your care.

The part of Medicare that pays for your medications. Part D comes either built into a Medicare Advantage plan or as a separate "standalone" plan that pairs with Original Medicare.

A Part C plan. One card, one phone number, often $0 premium, with built-in extras. You may have to use the insurance company's contracted providers (in-network) to get the most out of your policy and may need prior authorization for certain procedures.

A separate policy, sold by private carriers, that pays what Traditional Medicare doesn't pay. The benefits vary quite a bit — from covering just a little of what Traditional Medicare doesn't pay, all the way to covering everything Traditional Medicare doesn't. Check with your Golden Guardian agent to see which plan is right for you. Does not include prescription drugs — you'll need a standalone Part D plan alongside it.

A plan type that requires you to stay in a defined network of doctors and hospitals, and usually requires a primary care physician (PCP) who coordinates your care.

A plan type that lets you see in-network doctors at the lowest cost, and out-of-network doctors for a higher cost.

A Medicare Advantage plan designed for people with a specific condition (chronic SNP), people who qualify for both Medicare and Medicaid (dual SNP), or people living in a nursing facility (institutional SNP). Benefits are tailored to that group.

A prescription drug plan you buy separately when you have Original Medicare or a Medicare Supplement. Doesn't cover doctor visits or hospital stays — just your medications.

The monthly amount you pay just to have the coverage — whether you use it or not. Like a gym membership: it's a flat monthly bill.

A dollar amount you have to pay first each year before the plan starts paying its share. Once you've met the deductible, the plan picks up its portion.

A fixed dollar amount you pay for a specific service — for example, $10 for a primary care visit or $45 for a specialist.

A percentage of the bill you pay for a covered service — for example, 20% of the approved (contracted) amount for an MRI. Unlike a copay, it's tied to the size of the bill.

The most you'll pay for covered medical services in one calendar year. Once you hit it, the plan covers 100% of in-network medical costs for the rest of the year. Medicare Advantage plans are required to have a MOOP; Original Medicare doesn't.

The dollar amount Medicare or your plan has decided is fair for a given service. Your cost share is usually calculated off the allowed amount, not the provider's sticker price.

A blanket term for every dollar the plan passes on to you — deductibles, copays, and coinsurance added together.

The list of doctors, hospitals, clinics, labs, and pharmacies that have a contract with your plan. In-network means lower cost. Out-of-network means higher cost, and sometimes no coverage at all.

In-network is "contracted with your plan." Out-of-network is "not contracted with your plan." On a Medicare Advantage HMO, out-of-network care may not be covered except in an emergency.

The main doctor who manages your overall care. On an HMO, your PCP is usually the starting point for referrals to specialists.

A formal okay from your PCP to see a specialist. Some plans require referrals; many Medicare Advantage PPOs don't.

The plan's advance approval for a specific service, medication, or device. The doctor's office submits the request and the plan says yes or no (or "yes, with conditions") based on medical necessity.

The plan's decision not to pay for a service. Every denial can be appealed. A denial is not the end of the conversation — it's the start of one.

The formal process to ask the plan to reconsider a denial. There are multiple levels — starting with the plan itself, then moving up to an independent reviewer, then an administrative law judge, and so on. Deadlines are tight (typically 60 days), so if you get a denial letter, don't wait. Call your insurance company to understand their decision on the appeal.

A statement from the plan that tells you what was billed, what the plan paid, what you owe, and what your deductibles and out-of-pocket look like year-to-date. It is not a bill — it's a summary.

The list of medications a plan covers, grouped into "tiers." Tier 1 is usually the cheapest (generics); tier 4 or 5 the most expensive (specialty drugs). Plans can change the formulary between years, which is why reviewing at AEP matters.

A category within the formulary that determines what you pay. The same drug can sit on different tiers at different plans, which is how two plans can cover the same medication and have very different costs.

A generic is the chemical equivalent of a brand-name drug, typically priced much lower. Generics usually sit on the lowest tiers. Brand-name drugs typically sit higher.

A feature of most Part D plans that lets you get a 90-day supply of maintenance medications shipped to your home, usually at a lower copay than a 30-day retail fill.

A plan rule that requires you to try a lower-cost drug first before it will cover the more expensive one. Common for biologics and specialty medications.

The running tally of what you've spent on covered drugs that counts toward the $2,100 annual cap.

A federal program that lowers your Part D premiums, deductibles, and copays if you have a limited income. Most people who qualify don't know they do. Apply at ssa.gov/extrahelp.

The 7-month window around your 65th birthday when you first sign up for Medicare — 3 months before the month you turn 65, the month itself, and 3 months after. Missing it can cost you a permanent penalty.

October 15 through December 7 every year. This is the main window for Medicare Advantage and Part D changes. Any change you make here takes effect January 1.

January 1 through March 31. A once-a-year chance, if you're already in a Medicare Advantage plan, to switch to a different MA plan or go back to Original Medicare. You can only use it once.

A window triggered by a life event — moving out of a plan's service area, losing employer coverage, qualifying for Medicaid, and several other situations — that lets you enroll or switch outside the regular windows.

A permanent surcharge added to your Part B or Part D premium if you didn't enroll when you were first eligible and didn't have other creditable coverage. Stays with you for life.

A separate federal-and-state program for people with limited income and resources. You can have both Medicare and Medicaid at the same time — that's called being "dual-eligible," and it unlocks richer benefits.

Qualifying for both Medicare and Medicaid.

A state-run program that helps pay your Part B premium (and sometimes deductibles and coinsurance) if your income is limited but you don't fully qualify for Medicaid.

See section 6 — the federal subsidy that reduces Part D drug costs for people with limited income.

A free, unbiased counseling service in every state. They don't sell anything. If you ever want a second opinion on something I've told you, call your state's SHIP — I'll give you the number.

A letter from your Medicare Advantage or Part D plan, mailed in September, that tells you everything changing for next year — premiums, copays, formulary, network, extras. This is the single most important piece of mail you'll get all year.

The long, detailed contract from your plan that describes every benefit and rule for the year. These documents can be 100+ pages. They are long, complicated, and not easy to understand. If you have a question about your coverage or something in your EOC, please reach out to your insurance company's customer service department or call your Golden Guardian agent for assistance.

The short, user-friendly version of your plan's benefits. Good for comparison shopping.

A quarterly statement from Original Medicare that lists the services Medicare paid for. Not a bill — a summary. The Medicare Advantage equivalent is the EOB.

A red-white-and-blue booklet that arrives 3 months before your 65th birthday (if you're on Social Security). It includes your Medicare card and a summary of your rights.