Medicare Glossary

Annual Enrollment Period (AEP)

The period each year from October 15 through December 7 when Medicare beneficiaries can change their Medicare Advantage or Part D drug plans. Changes take effect January 1 of the following year.

Also known as: Fall Open Enrollment

Annual Notice of Change (ANOC)

A document that Medicare Advantage and Part D plans must send to enrollees by September 30 each year. It outlines any changes to the plan's costs, coverage, or service area that will take effect January 1.

Also known as: ANOC

COBRA Continuation Coverage

A federal law allowing you to temporarily keep employer group health coverage after leaving a job, usually at your own full cost. COBRA is not considered creditable coverage for delaying Medicare enrollment, so missing your Medicare window while on COBRA can trigger a penalty.

Also known as: COBRA

Creditable Coverage

Health or prescription drug coverage that is at least as good as Medicare's standard coverage. If you have creditable coverage when you turn 65, you may be able to delay enrolling in Medicare without facing a late enrollment penalty.

Disenrollment

The process of leaving a Medicare Advantage or Part D plan. You can only disenroll during specific enrollment periods, such as the Annual Enrollment Period or a Special Enrollment Period. When you disenroll from a Medicare Advantage plan, you return to Original Medicare.

Employer Group Health Plan (EGHP)

Health coverage offered through an employer, either your own or a spouse's, that may let you delay Medicare enrollment without a late penalty if the coverage is creditable and the employer has 20 or more employees.

Also known as: EGHP, Group Health Plan

Evidence of Coverage (EOC)

A detailed description of what your Medicare Advantage or Part D plan covers, how much it costs, and how the plan works. Plans must send you an EOC each year by October 15.

Also known as: EOC

Health Savings Account (HSA)

A tax-advantaged savings account paired with a high-deductible health plan, used to pay for qualified medical expenses. Once you enroll in any part of Medicare, you can no longer contribute new funds to an HSA, though you can still use existing funds.

Also known as: HSA

Initial Enrollment Period (IEP)

The 7-month window around your 65th birthday during which you can first sign up for Medicare. It includes the 3 months before your birthday month, your birthday month, and the 3 months after. Enrolling during the first 3 months gets you the earliest coverage start.

Also known as: IEP

Open Enrollment Period (OEP)

For Medicare Advantage, the period from January 1–March 31 each year when enrolled MA beneficiaries can switch to a different MA plan or return to Original Medicare (with Part D if desired). Changes take effect the first of the following month.

Also known as: OEP, Medicare Advantage OEP

Rollover

The ability to carry unused Health Savings Account (HSA) or Health Reimbursement Account (HRA) funds from one year to the next. Note: Once you enroll in any part of Medicare, you can no longer contribute to an HSA.

Special Enrollment Period (SEP)

A window outside the standard enrollment periods during which you can join, switch, or drop a Medicare plan. SEPs are triggered by qualifying life events such as losing employer coverage, moving, gaining Medicaid eligibility, or your plan leaving the area.

Also known as: SEP

Summary of Benefits

A standardized document that Medicare Advantage and Part D plans must provide that summarizes the plan's costs, covered benefits, and important rules. It is a shorter, easier-to-read version of the Evidence of Coverage.

ZIP Code Enrollment

The process of using your ZIP code to find Medicare Advantage or Part D plans available in your area. Plan availability, provider networks, and premiums can vary significantly based on your geographic location.