Glossary
Medicare insurance words, in plain English
Agents, ads and mailers use a lot of shorthand. Here's what the words mean, one or two sentences each, so you can follow the conversation and ask better questions.
Last reviewed October 26, 2026. General information, not advice about any plan.
Kinds of coverage
- Original Medicare
- Part A and Part B, run by the federal government. You can see any doctor or hospital in the U.S. that accepts Medicare.
- Part A
- Hospital insurance: inpatient stays, skilled nursing care after a hospital stay, hospice and some home health care.
- Part B
- Medical insurance: doctor visits, outpatient care, lab tests, preventive care and medical equipment. Most people pay a monthly premium.
- Part C (Medicare Advantage)
- A private plan that replaces Original Medicare's way of paying for Part A and Part B, usually with a network of doctors. Many include drug coverage and extra benefits.
- Part D
- Prescription drug coverage from a private plan, either on its own alongside Original Medicare or built into a Medicare Advantage plan.
- Medicare Supplement (Medigap)
- Private insurance that works with Original Medicare to pay some of your share of costs. In most states, plans have letters, such as Plan G, and each letter has the same basic benefits at every company. Massachusetts, Minnesota and Wisconsin differ.
- Extra Help
- A federal program that lowers Part D drug costs for people with limited income and resources.
- Medicare Savings Programs
- State programs that help pay Medicare premiums, and sometimes other costs, for people with limited income.
Enrollment periods
- Initial Enrollment Period
- Seven months around your 65th birthday: the 3 months before your birthday month, that month, and the 3 months after.
- Annual Enrollment Period
- October 15 to December 7 each year. You can join, switch or drop Medicare Advantage and Part D plans, with changes starting January 1.
- Medicare Advantage Open Enrollment
- January 1 to March 31. If you're in a Medicare Advantage plan, you can make one change: to another Medicare Advantage plan, or back to Original Medicare.
- Medigap Open Enrollment
- Six months starting the month you're 65 or older and have Part B. Companies can't turn you down or charge more for health reasons during this time.
- Special Enrollment Period
- A chance to change coverage outside the usual dates because something happened, such as moving or losing other coverage.
Your own dates depend on your situation. Medicare.gov, 1-800-MEDICARE or a licensed agent can tell you which apply.
Words about agents
- Licensed agent, broker or producer
- Someone licensed by your state to sell insurance. "Producer" is the legal term many states use.
- NPN (National Producer Number)
- A unique number each licensed agent gets once and keeps in every state. Use it to look them up.
- Line of authority
- The kinds of insurance a license covers. Medicare plans need a health line, often called "Accident & Health."
- Resident and nonresident license
- A resident license is from the agent's home state; a nonresident license lets them work in another state. Both are valid.
- Appointment
- An insurance company's approval for an agent to sell its plans.
- Captive and independent agent
- Industry terms, not official Medicare categories. Generally, a captive agent sells for one insurance company and an independent agent for several.
- Agent of record
- The agent an insurance company has on file for your policy.
- Scope of Appointment
- A short form confirming which kinds of plans you want to discuss before a sales meeting about Medicare Advantage or drug plans. It isn't an enrollment, and it's good for 12 months.
- TPMO
- Third-party marketing organization: an agent, broker or company that sells Medicare plans for insurers. If they sell for more than one company, they must tell you how many companies and plans they represent before discussing benefits.
- FMO
- Field marketing organization: a company agents contract through to work with insurers.
- SHIP
- Your state's State Health Insurance Assistance Program: free, unbiased Medicare counseling. They don't sell plans.
- Senior Medicare Patrol (SMP)
- A free national program that helps people spot and report Medicare fraud and errors. Call 1-877-808-2468.
Want to check an agent? Here's how to look up a license in your state.
Keep reading
- Medicare agent vs. broker: what's the difference?Agent, broker, producer: what the words mean, the one difference that really matters (how many companies they work with), and how to tell before you meet.
- What to bring to your first meeting with a Medicare agentA one-page checklist: the cards, doctor list and prescriptions an agent needs to compare plans for you, plus what you should never hand over.
- How to check an insurance agent's licenseLook up any agent with your state's insurance department, in about two minutes.
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