1. Time in which individuals may apply for life insurance or health insurance. 2. Time in which individuals may choose either to re-enroll in an existing managed care plan or change to a competitor’s plan. See also open enrollment period, federal open enrollment , and group enrollment period . 3. Specified time when an individual can sign up for Medicare benefits. The period for general enrollment is January 1 through March 31 of each year for Medicare supplementary insurance. 4. Certain period of time when an individual can join a Medicare health plan if it is open and accepting new Medicare members. If a health plan chooses to be open, it must allow all eligible people with Medicare to join.