If you’re a federal retiree, do not need to take Medicare part B at 65. But if you later, decide that you do want Medicare part B you will be able to enroll in it but you will get a 10% per year late penalty for every year past age 65 that you did not have Medicare part B being on your federal retirement Blue Cross health plan is not credible coverage for part B but it is for part D. | The Medicare Family