How Much Does Medicare B Cost Per Month? 
Medicare Part B premiums are based on your income . For most people , your Part B premium is $ 104.90 per month for 2013 , but high income earners could pay as much as $ 335.70 per month . If you do n't sign up for Part B when you are eligible , you may have to pay a late enrollment penalty . Your Part B will have a $ 147 annually deductible and a 20 % co-insurance . The important item to remember is that 20 % co-insurance has no limit . 