A medical biller’s expertise in coding systems is essential for accurate billing and insurance claims processing. By asking this question, interviewers want to assess your knowledge of these coding systems, as well as your ability to explain complex concepts in a clear manner. The International Classification of Diseases (ICD-10) codes are used for diagnosis coding, while Current Procedural Terminology (CPT) codes are used for documenting medical procedures. Showcasing your understanding of these codes is key to demonstrating your competency in medical billing.