What are CPT add-on codes used for?

CPT add-on codes serve a specific purpose in medical billing and coding. These codes are intended for procedures that are always performed in conjunction with a primary procedure. The nature of add-on codes is that they cannot stand alone; they are supplementary to a primary code and are used to describe additional procedures performed at the same time.

For instance, if a physician is performing a complex surgery and also conducts another procedure that enhances or is an integral part of that surgical process, the add-on code would clearly indicate the nature of this additional procedure. This helps in accurate billing and ensures that the healthcare provider is appropriately reimbursed for all services rendered during the operative session.

In contrast to the correct answer, the other choices do not align with the definition and purpose of add-on codes. Procedures that are independent of any primary service would not require an add-on code, as these are typically billed separately. The requirement for separate documentation generally applies to various medical services but is not exclusive to add-on codes. Lastly, having multiple code options refers to the variety of choices available for coding a service but does not directly pertain to the function of add-on codes.