As soon as you are determined to be eligible for Medicare, you will automatically be enrolled for Hospital insurance coverage (Part A). You pay nothing for this coverage. You will also be automatically enrolled for Medical insurance coverage (Part B). You will have to pay a monthly premium for Part B. If you receive an annuity, the premium will usually be deducted from your monthly annuity rate. If you later choose not to receive Part B coverage, you must notify the Railroad Retirement Board.