The main responsibilities and duties include interpreting the medical record for office visits or procedures and choosing the correct code for payment from the insurance company involved. In some practices, the coding is done by the clinicians and the coder just audits. The main responsibility is that all claims leaving the office should be free of abuse, fraud, or incorrect information.
Do mistakes happen? Yes, of course. However, none of these types of mistakes should be intentional and the coder should see all things leaving the office.
The next most important duty is the education of the clinical and front desk staff so that everyone understands how important their job is in the whole claim cycle.