What is Annual Enrollment Period (AEP)?

The window each year, October 15 through December 7, when anyone with Medicare can switch Medicare Advantage plans, change Part D drug plans, or move between Original Medicare and Medicare Advantage. Changes take effect January 1.

What is Annual Notice of Change (ANOC)?

A notice your Medicare Advantage or Part D plan sends every September, explaining what's changing about your specific plan for the coming year — premium, deductible, copays, network, or formulary.

The maximum amount CMS will pay a Medicare Advantage plan in a given county, used to help determine plan bids, extra benefits, and rebates in that area.

What is Benefit Period?

How Medicare Part A measures a hospital or skilled nursing facility stay for cost-sharing purposes. A benefit period begins the day you're admitted and ends after you've been out of the hospital and any skilled nursing facility for 60 consecutive days — you can have more than one benefit period, and pay the Part A deductible again, within a single year.

What is Chronic Condition Special Needs Plan (C-SNP)?

A type of Medicare Advantage Special Needs Plan designed for people with specific, severe chronic conditions, such as diabetes or heart failure, offering care coordination and benefits tailored to that condition.

Medicare Glossary

Medicare Terms, in Plain English

Medicare is full of acronyms and jargon that don't mean much until someone explains them — below are 55 of the terms you'll run into most often, defined in plain language, no insurance-speak required.

Written by Kayla Price, Licensed Medicare Agent (NPN 18530055)

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Annual Enrollment Period (AEP): The window each year, October 15 through December 7, when anyone with Medicare can switch Medicare Advantage plans, change Part D drug plans, or move between Original Medicare and Medicare Advantage. Changes take effect January 1.
Annual Notice of Change (ANOC): A notice your Medicare Advantage or Part D plan sends every September, explaining what's changing about your specific plan for the coming year — premium, deductible, copays, network, or formulary.
Benchmark: The maximum amount CMS will pay a Medicare Advantage plan in a given county, used to help determine plan bids, extra benefits, and rebates in that area.
Benefit Period: How Medicare Part A measures a hospital or skilled nursing facility stay for cost-sharing purposes. A benefit period begins the day you're admitted and ends after you've been out of the hospital and any skilled nursing facility for 60 consecutive days — you can have more than one benefit period, and pay the Part A deductible again, within a single year.
Chronic Condition Special Needs Plan (C-SNP): A type of Medicare Advantage Special Needs Plan designed for people with specific, severe chronic conditions, such as diabetes or heart failure, offering care coordination and benefits tailored to that condition.
CMS (Centers for Medicare & Medicaid Services): The federal agency within the U.S. Department of Health and Human Services that administers Medicare, Medicaid, and the ACA Marketplace, and sets the rules private insurers must follow to sell Medicare plans.
Coinsurance: The percentage of a Medicare-approved cost you're responsible for after meeting your deductible — for example, the standard 20% Part B coinsurance for most outpatient services. Different from a copayment, which is a flat dollar amount.
Coordination of Benefits: The process that determines which of your insurance plans pays first (primary) and which pays second (secondary) when you have more than one type of coverage, such as Medicare and an employer plan. See Medicare Secondary Payer for the specific rules governing this with Medicare.
Copayment (Copay): A flat dollar amount you pay for a covered service, such as $20 for a doctor visit — different from coinsurance, which is a percentage of the cost rather than a fixed amount.
Cost-Sharing: The general term for the portion of healthcare costs you pay yourself, including premiums, deductibles, copayments, and coinsurance — as opposed to what your plan pays.
Creditable Coverage: Health or drug coverage considered at least as good as Medicare's. Having creditable coverage (such as through a current employer) lets you delay Medicare enrollment without facing a late enrollment penalty later.
Dual-Eligible: Someone who qualifies for both Medicare and Medicaid at the same time. Medicaid can help cover Medicare premiums and cost-sharing, and often covers services Medicare doesn't, like long-term custodial care.
Durable Medical Equipment (DME): Medically necessary equipment for home use, like wheelchairs, walkers, and hospital beds, generally covered under Part B when prescribed by a doctor.
Enrollment Period: The general term for any of Medicare's defined windows — Initial, General, Special, or Annual — during which you can enroll in or change coverage. See each specific period for its own rules and timing.
Evidence of Coverage (EOC): A detailed annual document your Medicare Advantage or Part D plan provides, explaining exactly what the plan covers, what it costs, and your rights as a member — more comprehensive than the summary you typically see when comparing plans.
Extra Help: A federal program that helps people with limited income and resources pay for Medicare Part D prescription drug costs, including premiums, deductibles, and copays.
Formulary: The list of prescription drugs a specific Part D or Medicare Advantage plan covers, organized into cost tiers. Two plans can cover the same drug at very different costs depending on its tier.
General Enrollment Period (GEP): A window running January 1 through March 31 for people who missed their Initial Enrollment Period and don't qualify for a Special Enrollment Period. Coverage typically starts the month after you enroll, and a late-enrollment penalty may apply.
Guaranteed Issue Rights: Federal protections that require a Medigap insurer to sell you a policy regardless of health history, without charging more due to past or present health problems, in specific situations — such as during your Medigap Open Enrollment Period or after losing certain other coverage.
Guaranteed Renewable: A feature of Medigap policies meaning the insurer cannot cancel your policy as long as you pay your premium on time, regardless of your health or how many claims you've filed.
Hospice Care: End-of-life comfort care for people with a terminal diagnosis and a life expectancy of 6 months or less, covered under Medicare Part A, focused on comfort rather than curative treatment.
Initial Coverage Election Period (ICEP): The window, generally aligned with your Initial Enrollment Period, during which you can first enroll in a Medicare Advantage plan when you become eligible for Medicare.
Initial Enrollment Period (IEP): The 7-month window to first sign up for Medicare, centered on your 65th birthday — 3 months before, the month of, and 3 months after.
IRMAA (Income-Related Monthly Adjustment Amount): An extra amount added to your Part B and Part D premiums if your income, based on your tax return from two years prior, is above a certain threshold.
Late Enrollment Penalty: A permanent premium increase applied to Part B or Part D if you enroll late without qualifying employer coverage or another valid exception. The penalty is added to your premium for as long as you have that coverage.
Lifetime Reserve Days: 60 additional hospital days Medicare Part A provides beyond the standard 90 days covered in a benefit period, usable only once over your lifetime, with a daily coinsurance cost.
Medicare: The federal health insurance program run by the Centers for Medicare & Medicaid Services (CMS), primarily covering people age 65 and older and certain younger people with qualifying disabilities.
Medicare Advantage: See Medicare Part C. A private plan approved by Medicare that replaces Original Medicare, typically using a provider network (HMO or PPO) and often bundling drug coverage and extra benefits.
Medicare Advantage Open Enrollment Period (MA OEP): A window running January 1 through March 31 that lets people already enrolled in a Medicare Advantage plan make one additional plan switch, or return to Original Medicare.
Medicare Number: The unique identifier on your red, white, and blue Medicare card, used to verify your identity and coverage — different from your Social Security number, which it no longer matches for privacy reasons.
Medicare Part A: Hospital insurance. Covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health care. Most people pay no premium for Part A if they or a spouse paid Medicare taxes for at least 10 years.
Medicare Part B: Medical insurance. Covers doctor visits, outpatient care, preventive services, and durable medical equipment. Most people pay a standard monthly premium ($202.90 in 2026) plus an annual deductible ($283 in 2026).
Medicare Part C: Also called Medicare Advantage — a private-insurance alternative to Original Medicare that bundles Part A, Part B, and usually Part D into one plan, often with extra benefits like dental and vision.
Medicare Part D: Prescription drug coverage, sold as a standalone plan or bundled into a Medicare Advantage plan. As of 2026, Part D has a $2,100 annual out-of-pocket cap on covered drugs.
Medicare Savings Program (MSP): A state-run program that can help pay Medicare premiums, deductibles, copays, and coinsurance for people with limited income and resources.
Medicare Secondary Payer: Federal rules that determine when Medicare pays second, after another insurer (such as an employer group health plan), rather than paying first. Getting the payment order wrong can result in denied claims or unexpected bills.
Medicare Supplement: See Medigap.
Medigap: Also called Medicare Supplement insurance — a policy sold by private insurers that works alongside Original Medicare to cover its cost-sharing gaps (coinsurance, copays, and in some plans, deductibles). Cannot be used with Medicare Advantage.
Medigap Open Enrollment Period: A one-time, 6-month window starting the month you're both 65+ and enrolled in Part B, during which Medigap insurers must generally sell you any policy they offer regardless of health history.
Network: The group of doctors, hospitals, and other providers that a Medicare Advantage plan has contracted with. Using an in-network provider typically costs less than going out-of-network, and some plan types (HMOs) may not cover out-of-network care except in emergencies.
Open Enrollment Period (OEP): See Medicare Advantage Open Enrollment Period (MA OEP) — the January 1 through March 31 window for people already in a Medicare Advantage plan to make one plan switch or return to Original Medicare.
Original Medicare: The traditional federal Medicare program made up of Part A (hospital insurance) and Part B (medical insurance), run directly by the federal government with no networks — any provider that accepts Medicare, anywhere in the country, will treat you.
Out-of-Pocket Maximum (OOPM): The most you'll pay in a plan year for covered services under a Medicare Advantage plan before the plan pays 100% of covered costs. Original Medicare alone has no out-of-pocket maximum, which is part of why many people pair it with Medigap or a Medicare Advantage plan.
PACE (Program of All-Inclusive Care for the Elderly): A Medicare and Medicaid program providing comprehensive medical and social services to help frail, older adults continue living in their community rather than a nursing home.
Premium: The amount you pay, usually monthly, to have insurance coverage — separate from what you pay when you actually use care (deductibles, copays, coinsurance).
Prior Authorization: A requirement that your plan approve certain services or medications before you receive them, confirming the care is medically necessary before the plan agrees to pay.
Provider: A person or organization, such as a doctor, hospital, or clinic, that delivers healthcare services and bills Medicare or your plan for that care.
Qualified Medicare Beneficiary (QMB): A Medicare Savings Program for people with limited income that helps pay Part A and Part B premiums, deductibles, coinsurance, and copayments.
SHIP / SHIIP (State Health Insurance Assistance Program): A free, unbiased counseling service, funded by the federal government and run at the state level, that helps people with Medicare questions and plan comparisons at no cost.
Skilled Nursing Facility (SNF) Care: Short-term nursing and rehabilitation care following a qualifying hospital stay, covered under Part A for a limited number of days per benefit period, with coinsurance after the first 20 days.
Special Enrollment Period (SEP): A window outside the standard enrollment periods that opens when you have a qualifying life event — such as moving, losing employer coverage, or losing Medicaid — allowing you to enroll in or change Medicare coverage.
Special Needs Plan (SNP): A type of Medicare Advantage plan designed for people with specific needs — dual-eligible beneficiaries (Medicare + Medicaid), those in institutional care, or those with certain chronic conditions. Often includes extra tailored benefits.
Star Rating: A 1-to-5 star quality score CMS assigns to Medicare Advantage and Part D plans each year, based on member satisfaction, care quality, and plan performance — a useful factor when comparing plans, alongside cost and network.
Step Therapy: A plan rule requiring you to try a lower-cost drug first before the plan will cover a more expensive alternative for the same condition, unless the lower-cost option isn't appropriate for you.
TrOOP (True Out-of-Pocket Costs): The costs that count toward your Part D out-of-pocket total — what you (or others on your behalf) actually pay for covered drugs. Once TrOOP reaches the annual cap, the Part D out-of-pocket maximum kicks in.

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