Late Enrollment Penalty
This is a sum of money added to your monthly premium for a Prescription Drug Plan or for Medicare Part B if you don’t join as soon as you become eligible. This penalty is payable for the entire time you have Medicare, though there are a few exceptions. The penalty is 10% for every full 12-month period you did not sign up for Medicare when you were eligible. So if you waited 18 months, this is counted as one full 12-month period, which means you would be hit with a 10% penalty.
Susan did not enroll in a Medicare plan when she became eligible. She did not qualify for a late enrollment exception and is now paying a monthly premium penalty.