When is the open enrollment period for Medicare?

Medicare's initial enrollment period is a seven-month window that begins three months before an individual's birth month and ends three months afterward. For example, someone born in June can sign up from March 1 to Sept. 30. Individuals also can enroll Jan. 1 through March 31, according to Medicare.

Individuals who miss the enrollment period that's tied to their birthday may pay a penalty for signing up during the general enrollment period of January through March, advises Medicare. Coverage begins July 1 for individuals who choose the general enrollment period. Medicare has separate enrollment periods for employees who are covered by an employer's group health policy.