Individuals who are 65 or older are eligible for Medicare. Medicare requires enrollment at particular triggering events and at specific times throughout the year. If you are receiving retirement benefits under the social security program, you will be automatically enrolled in Medicare Part B at age 65. If you are covered under a larger group health plan (20 or more employees), you can opt out of Part B and Part D coverage without a penalty.
A specific triggering event (e.g., when you lose group employer coverage) requires that you enroll during the special enrollment period. Enrolling within eight months of a triggering event will help avoid Part B penalties but may not prevent coverage gaps. You should start the enrollment process at least three months before a triggering event occurs to avoid gaps in coverage or the risk of missing a penalty deadline.