Medicare Glossary

Plain-English definitions for the terms you will see on this site and in plan materials.

AEP

Annual Enrollment Period, October 15 through December 7, when you can generally change Medicare Advantage or Part D coverage for January 1.

Formulary

The list of drugs a Part D or Medicare Advantage plan covers, often grouped in cost tiers.

IRMAA

Income-Related Monthly Adjustment Amount — an extra amount higher-income people may pay for Part B and Part D.

Medigap

Medicare Supplement insurance that helps pay certain Original Medicare cost-sharing amounts.

MOOP

Maximum out-of-pocket — the most you should pay in a year for covered in-network Part A and B services in a Medicare Advantage plan.

SEP

Special Enrollment Period triggered by a qualifying event.

SOA

Scope of Appointment — a required documentation step before a Medicare Advantage or Part D sales appointment covering specific products.

Important: We are not affiliated with or endorsed by the U.S. Government or the federal Medicare program. This page is general education. Availability, eligibility, costs, and benefits can vary by plan and area.

AEP: Annual Enrollment Period (Oct 15–Dec 7).
Assignment: A doctor who accepts the Medicare-approved amount as full payment.
Creditable coverage: Drug coverage that is at least as good as Medicare’s standard Part D, on average.
D-SNP: Dual Special Needs Plan for people with Medicare and Medicaid.
Formulary: A plan’s list of covered drugs.
IEP: Initial Enrollment Period around your 65th birthday.
IRMAA: Income-related extra premium for Part B and Part D.
Medigap: Medicare Supplement insurance.
MOOP: Medicare Advantage in-network maximum out-of-pocket for Parts A and B.
PDP: Standalone Part D prescription drug plan.
SEP: Special Enrollment Period.
SOA: Scope of Appointment documentation for certain Medicare sales meetings.