How Much Is Medicare Part B Premium For 2013? 
Most people will pay $ 104.90 per month for their Part B premium in 2013 . This may be higher for people with high incomes . However , if you do n't sign up for Part B when you 're first eligible , you may have to pay a late enrollment penalty for as long as you have Medicare . Your monthly premium for Part B may go up 10 % for each full 12-month period that you could have had Part B , but did n't sign up for it . 