Unlike large employer group plans,  employees on small group plans (fewer than 20) are required to enroll in Medicare Part B when they turn 65. Part B helps cover the cost of doctor visits, outpatient care, some preventative services, home health care and durable medical equipment. Once you enroll in Part B you have 6 months to purchase a Medicare Supplement without going through medical underwriting (being required to answer medical questions). If you have concerns about being declined or charged a higher premium due to your health status you should purchase your own plan before the end of this six month window.