When all of your medical bills are added up, you will see that Medicare pays, on average, only about half the total. There are three major reasons why it pays so little.
First, Medicare does not cover a number of major medical expenses, such as glasses, hearing aids, dental work, dentures, and a number of other costly medical services.
Second, Medicare pays only a portion of what it decides is the proper amount -- called the approved charges -- for medical services. When Medicare decides that a particular service is covered, it determines the approved charges for it. Part B medical insurance then usually pays only 80% of those approved charges; you are responsible for the remaining 20%.
Third, the approved amount may seem reasonable to Medicare, but it is often considerably less than what doctors actually charge. If your doctor or other medical provider does not accept assignment of the Medicare charges, you are personally responsible for the difference, up to a certain maximum.
Note that there are now several types of treatments and medical providers for which Medicare Part B pays 100% of the approved charges rather than the usual 80%. These categories of care include home health care, clinical laboratory services, and flu and pneumonia vaccines.
For details, see our article on what Medicare Part B will pay.