Can I Sign Up For Medicare Part B Late? 
You can sign up for Medicare Part B late , but there may be penalties . If you do not enroll in Medicare Part B when you first become eligible , you can enroll during the open enrollment period from January 1 and March 31 each year . If you sign up during this period , your plan will become effective July 1 . You will be charged an additional 10 % on your premium for every 12 months you went without coverage . However , if you did n't enroll because you were covered by a different insurance plan , you can sign up during the eight months following the end of that plan without a penalty . 