Question: I-ve never really understood E codes and when I should use them. Would you explain what they are exactly and why I need to add them to my claims? Minnesota Subscriber Answer: E codes describe external causes of injuries or accidents. They range from the common (E880.9, Fall on or from other stairs or steps) to the obscure (E847, Accidents involving cable cars not running on rails). Basically, E codes can help you explain to payers how an injury happened. Pointer: E codes do not change your reimbursement amount because they are really for informational purposes only. You should never report E codes in lieu of a diagnostic code to describe an injury, but E codes help the carrier understand how the patient was injured. They also support the work-related nature of certain injuries to differentiate workers' compensation (WC) care from non-WC care. Although the E codes aren't payment codes, they explain the "environmental events, circumstances and conditions" that caused the injury, states the ICD-9 manual. Therefore, you should never report an E code as your primary diagnosis, but instead list it after the main diagnosis. The answers to the Reader Questions and You Be the Billing Expert were reviewed by Barbara J. Cobuzzi, MBA, CPC-OTO, CPC-H, CPC-P, CPC-I, CHCC, president of CRN Healthcare Solutions in Tinton Falls, N.J. and senior coder and auditor for The Coding Network.