Yes -- doctor bills are probably the biggest chunk of outpatient expenses that are covered by Part B. The category includes any service by a doctor wherever it's provided -- hospital, doctor's office, clinic. It also covers any other work performed by the doctor's staff, as well as any drugs administered in the office.

The two basic coverage rules are that care must be medically necessary, and it must be performed by a doctor who accepts Medicare payment. This means that before participants see any new doctor, they must make sure that the doctor accepts Medicare.

With many limitations, Part B also covers some care by a chiropractor. This is only for short-term manipulation of out-of-place vertebrae -- neck and back -- by a Medicare-certified chiropractor. Before seeing a chiropractor, have the chiropractor's office check directly with Medicare to ensure coverage.