What is 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.

What is 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.

What is 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).

What is 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.

What is 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 Glossary

Medicare Terms, in Plain English

Medicare is full of acronyms and jargon that don't mean much until someone explains them — below are 23 of the terms you'll run into most often, defined in plain language, no insurance-speak required.

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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.
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 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.
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.
Medicare Supplement: See Medigap.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Out-of-Pocket Maximum: 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.
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.

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