initial open enrollment period
Usually the best time to enroll in Original Medicare is during the Medicare Initial Enrollment Period. During this time, beneficiaries may opt to enroll in Original Medicare, Medicare Advantage (Part C), or Medicare Part D prescription drug coverage. The Initial Enrollment Period (IEP) differs for each beneficiary. Generally, this seven month period: Begins three months before the beneficiaryâs month of eligibility. Includes the eligibility month. Lasts for three months following the eligibility month.