To enroll in Medigap Plan N, enrollees must be enrolled in both Medicare Part A and Part B and live within their plans network. The best time to enroll in Medigap Plan N is during Medicare’s Open Enrollment Period, which will start the first day of the month that you are both over 65 and enrolled in Medicare Part B.
The open enrollment period will last for six months. During open enrollment, enrollees are guaranteed issue right to enroll in any plan of your choice, regardless of your health condition. Insurance companies may not use underwriting during six month period, but if you miss this period, then you might be subjected to medical underwriting and denied coverage.