If you are a veteran then you don’t have take Medicare. If you are on Social Security you will be automatically enrolled in Medicare Part A when you turn 65.
Veterans have to option of declining Part B since they can choose to participate in the VA system to get their health coverage.
A word of caution. Make sure of your eligibility before deciding to stay in the VA system. Also, if you later choose to pick up Part B for whatever reason you may subject to late enrollment penalties. For every twelve months you should have have had it you’ll pay a 10 percent penalty.