For Part A coverage , you don't usually pay a monthly premium if you or your spouse paid Medicare taxed while working for a certain amount of time. This is a premium-free Part A . If you are not eligible, then you will need to buy Part A. In most cases, if you choose to buy Part A, you must also have part B and pay monthly premiums for both. But you can still buy Part B even if you choose not to take Part A. People who have to buy Part A will pay up $458 every month in 2020. PART A LATE ENROLLMENT PENALTY If you aren't eligible for premium-free Part A and you don't buy it when you're first eligible, your monthly premium may go up to 10%. You'll have to pay higher premiums for twice the several years you could have had Part A but didn't sign up. For example, You were eligible for Part A for 2 years but didn't sign up, you'll have to pay a 10% higher premiums for 4 years. Standard Part B premium amount in 2020 is $144.60. Mo...