Some of these billing difficulties may be caused by: Mistakes in medical coding Instances where it is judged that your services are not completely covered by Medicare 3. Your assistance has been considered medically unnecessary. 4. You have been overpaid by Medicare. Billing errors can occur for many reasons. Sometimes the problem is with the provider - sometimes called "faulty practices." For example, a doctor might use the wrong diagnosis code or charge too much for his or her service. Other times the error is with Medicare. For example, if a provider bills incorrectly, then files an appeal but fails to respond to the appeals office, he or she will be dropped from the program. Billing errors can also be due to human error. For example, two providers may report the same procedure done on different patients as well as their associated charges. Yet, only one of them would actually receive payment. The other person's bill would contain the billing error. Billing errors can also result from software problems. For example, an electronic health record (EHR) system may fail to include all of the information required by Medicare regulations. This could cause a bill to be submitted incorrectly. Or, a provider may submit a claim using outdated instructions. When this happens, they are relying on pure luck to have their claim processed properly.