Medicare Parts A and B are sometimes called "Original Medicare." Original Medicare allows you the freedom to see any doctor who accepts Medicare. Most do. It’s not like an HMO, where you can see only doctors in the plan’s network.
Most people get signed up for Medicare Part B automatically. If you do not want it, you must opt out. Otherwise, the money is automatically taken out your Social Security payments. You should get instructions on how to do this when you are first mailed your Medicare packet.
Some people opt out of Medicare Part B because they still have coverage through union or employer health insurance. If you want to opt out, make this decision carefully. If you sign up later for Part B, you might have to pay a late penalty. You might want to talk to the group benefits administrator of your plan before opting out of Part B.
If you have traditional Medicare, make sure your doctor "accepts assignment" before you make an appointment. Medicare decides what it will pay for any particular medical service. This is called the Medicare-approved amount. If your doctor is willing to accept what Medicare pays and won't charge you any more, he or she is said to "accept assignment." But if your health care provider charges more than Medicare pays, you will have to pay the difference.
For more information about Medicare Part B, see the Medicare web site at www.medicare.gov or call 1-800-MEDICARE.