A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
A
Accept Assignment
When a doctor or provider agrees to accept the Medicare-approved amount as full payment for a service. If your provider accepts assignment, you typically pay only your standard coinsurance (often 20%).
Advance Beneficiary Notice (ABN)
A notice some providers may ask you to sign when they believe Medicare may not pay for an item or service. By signing, you agree to pay if Medicare denies the claim. Learn more under Medicare basics.
Allowed Amount (Medicare-Approved Amount)
The maximum fee Medicare sets for a covered service. Providers who accept assignment agree to this amount as payment in full.
Annual Enrollment Period (AEP)
The yearly window from October 15 to December 7 to join, switch, or drop a Medicare Advantage plan or a Part D prescription drug plan. Changes take effect January 1.
Annual Notice of Change (ANOC)
A letter from your current Medicare Advantage or Part D plan, sent by September 30, summarizing next year’s changes to benefits, costs, and rules so you can decide whether to stay or switch during the AEP.
Annual Wellness Visit (AWV)
A yearly visit covered by Part B (after you’ve had Part B for 12 months) to create or update a personalized prevention plan. Includes a health risk assessment, medication review, and screenings as appropriate. See What is Medicare?
Appeal
The formal process to ask Medicare or your plan to review and change a coverage, payment, or drug tiering decision you disagree with. You have rights and timelines for each appeal level.
Assignment (Medicare Assignment)
Medicare’s payment agreement for covered services. If a provider accepts assignment, they take the Medicare-approved amount as full payment. If they don’t, you may owe excess charges in some cases.
B
Balance Billing (Excess Charges)
When a provider who does not accept assignment bills you above the Medicare-approved amount. See also Medicare excess charges.
Beneficiary
Anyone who receives Medicare benefits — that’s you, if you’re enrolled in Medicare.
Benefit Period (Part A)
Begins the day you’re admitted as an inpatient and ends after 60 consecutive days without inpatient or skilled nursing facility care. A new benefit period means a new Part A deductible.
Brand-Name Drug
A prescription drug sold under a trademarked brand; may have a lower-cost generic equivalent.
C
Catastrophic Coverage (Part D)
The final Part D stage where your out-of-pocket drug costs are greatly reduced (often $0) for the rest of the plan year.
Centers for Medicare & Medicaid Services (CMS)
The federal agency that runs Medicare and partners with states to administer Medicaid.
COBRA
A law that lets you continue employer coverage for a limited time after certain qualifying events.
Coinsurance
Your share of costs as a percentage (e.g., Medicare pays 80%, you pay 20%).
Coordinated Care (Managed Care)
In Medicare Advantage, networks of doctors/hospitals work together to deliver cost-effective care.
Copayment (Copay)
A fixed dollar amount you pay for a covered service or drug.
Cost-Sharing
What you pay out of pocket: deductibles, copays, and coinsurance.
Creditable Drug Coverage
Non-Medicare coverage (like employer or VA) that’s at least as good as standard Part D.
Custodial Care
Help with daily activities (bathing, dressing). Not generally covered by Medicare.
D
Deductible
A set amount you pay before Medicare or your plan starts to pay.
Dual Eligible
Someone who has both Medicare and Medicaid. See Medicare Savings Program.
E
End-Stage Renal Disease (ESRD)
Permanent kidney failure requiring dialysis or transplant; qualifies you for Medicare at any age.
Excess Charges
Amounts a non-participating provider may bill above the Medicare-approved amount. Related: Balance billing.
Extra Help (Part D Low-Income Subsidy)
A program that helps qualified people pay Part D premiums and drug costs.
F
Formulary
A plan’s list of covered drugs, organized into tiers.
G
General Enrollment Period (GEP)
If you didn’t enroll in Part A and/or Part B when first eligible, you can sign up Jan 1–Mar 31. Coverage typically starts soon after you enroll; late penalties may apply.
Generic Drug
Same active ingredients and effectiveness as a brand-name drug, usually at lower cost.
Guaranteed Renewable (Medigap)
Medigap plans renew yearly if you pay your premium on time and didn’t misrepresent facts on your application.
H
Health Maintenance Organization (HMO)
A Medicare Advantage plan type that generally requires use of network providers (except emergencies/urgent care).
Home Health Care
Part-time skilled services (nursing or therapy) for homebound beneficiaries under Original Medicare.
Hospice Care
Comfort-focused care for terminal illness under Part A, including support for caregivers.
I
Initial Enrollment Period (IEP)
Your first chance to enroll in Medicare — a 7-month window around your 65th birthday (or disability eligibility).
Inpatient Care
Care you get after formal hospital admission. Ask if you’re “admitted” or “under observation,” as coverage differs.
J
J-Codes
HCPCS billing codes often used for injectable drugs and certain Part B medications administered in a clinical setting.
K
Medigap Plan K
A standardized Medigap plan that covers a percentage of certain cost-sharing with an annual out-of-pocket limit. Learn more on our Plan K page.
L
Lifetime Reserve Days (Part A)
Up to 60 additional hospital days you can use after day 90 in a benefit period. They don’t renew once used.
Long-Term Care
Ongoing help with daily activities (not typically covered by Medicare). See also custodial care.
M
Medicaid
State-run program (with federal rules/funding) that helps people with limited income; may cover premiums and cost-sharing for Medicare beneficiaries.
Medical Savings Account (MSA)
A Medicare Advantage plan combining a high deductible with an account you can use for medical costs.
Medically Necessary
Services/supplies needed to diagnose or treat a condition according to accepted medical standards.
Medicare
Federal health insurance for people 65+, certain younger people with disabilities, and those with ESRD or ALS. Start here: What is Medicare?
Medicare Advantage (Part C)
Private plans that bundle Part A and Part B, often with Part D and extra benefits. See Medicare Advantage.
Medicare-Approved Amount
The maximum amount Medicare pays for a covered service. See Accept assignment.
Medicare Assignment
When a provider agrees to accept the Medicare-approved amount as full payment.
Medicare Annual Enrollment Period (AEP)
Medicare Prescription Payment Plan
Lets Part D members spread certain out-of-pocket drug costs across the calendar year.
Medicare Savings Program
State programs that help eligible people pay Part A/Part B premiums and sometimes cost-sharing.
Medicare Supplement Insurance (Medigap)
Standardized plans from private insurers that help pay out-of-pocket costs of Original Medicare. Explore Medigap benefits and compare plans.
Medigap Open Enrollment Period
A 6-month window starting when you’re 65+ and enrolled in Part B. You can buy any Medigap plan sold in your area, regardless of health history.
N
Network
The doctors, hospitals, and pharmacies that contract with your Medicare Advantage or Part D plan.
O
Out-of-Pocket Costs
What you pay directly for care: deductibles, copays, and coinsurance.
Out-of-Pocket Limit
The maximum you’ll pay for covered services in a plan year (applies to Medicare Advantage, not Original Medicare).
Outpatient Care
Care you receive without being formally admitted to a hospital.
P
Part A
Hospital insurance — inpatient hospital, skilled nursing facility (after a qualifying stay), hospice, and some home health. See Medicare.
Part B
Medical insurance — doctor visits, outpatient care, preventive services, and durable medical equipment.
Part C (Medicare Advantage)
See Medicare Advantage.
Part D
Prescription drug coverage offered by private plans. Learn more: Part D basics.
Point-of-Service (POS) Plan
An HMO-type plan that lets you go out of network for some services, usually at higher cost.
Pre-Existing Condition (Medigap context)
A condition you had before coverage starts. Outside certain protections (like Medigap Open Enrollment or Guaranteed Issue rights), Medigap underwriting or waiting periods may apply.
Preferred Provider Organization (PPO)
A Medicare Advantage plan that covers in-network and out-of-network care (you’ll usually pay more out of network).
Premium
The amount you pay (often monthly) to keep your coverage.
Prescription Drug Plan (PDP)
A standalone Part D plan that helps pay for prescription drugs.
Preventive Care
Services that help prevent or detect illness early (e.g., flu shots, screenings). Many are covered by Part B.
Prior Authorization
Plan approval required before certain drugs or services will be covered.
Private Fee-For-Service (PFFS)
A Medicare Advantage plan where you can see any Medicare-eligible provider who agrees to the plan’s terms.
PACE
Program of All-Inclusive Care for the Elderly — helps people 55+ remain in their community with comprehensive services.
Provider
A person or organization that furnishes medical services (doctor, hospital, lab, pharmacy).
Q
Qualifying Disability
A disability that meets Social Security/RRB rules and may qualify you for Medicare before age 65.
R
Retiree Health Coverage
Group coverage offered to retired employees; may coordinate with Medicare.
S
Service Area
The geographic area where a plan operates and offers coverage.
Skilled Nursing Facility (SNF) Care
Daily skilled care (e.g., nursing, therapy) after a qualifying inpatient hospital stay, covered by Part A with limits.
Special Enrollment Period (SEP)
A time you can enroll or make changes due to certain life events (e.g., losing employer coverage) without penalties.
Special Needs Plan (SNP)
A Medicare Advantage plan tailored for specific groups (e.g., chronic conditions, institutionalized, or dual eligible).
Step Therapy
A Part D rule requiring you to try a lower-cost drug before “stepping up” to a more expensive one.
T
Tiered Formulary
Part D drugs are grouped into tiers with different cost-sharing (generics usually lowest, specialty drugs highest).
Telehealth
Virtual visits covered under Part B in many situations; availability may vary by plan and location.
U
Underwriting (Medigap)
A health review some insurers use when you apply for Medigap outside Open Enrollment or without Guaranteed Issue rights.
Urgent Care
Care for non-emergency conditions that need prompt attention. Covered by Original Medicare and most plans.
V
Vaccines
Shots to prevent disease. Some are covered by Part B (e.g., flu), others by Part D; check your plan’s formulary.
W
Waiting Period (Medigap)
Some Medigap policies may delay coverage for a pre-existing condition for up to 6 months, unless protected by Guaranteed Issue or you have prior creditable coverage.
Wellness Visit
X
X-Ray (Diagnostic Imaging)
A Part B-covered diagnostic test when medically necessary; coinsurance and deductible may apply.
Y
Yearly Deductible
An annual amount (such as the Part B deductible) you must pay before coverage begins for certain services.
Z
ZIP Code Rating (Geographic Rating)
How insurers may vary Medigap premiums based on where you live; prices differ by state and county.