What does the term "add-on code" mean in CPT coding?

The term "add-on code" in CPT coding specifically refers to a code that is used to report additional procedures performed simultaneously with a primary procedure. Add-on codes are designated to indicate that a secondary procedure or service is being performed in conjunction with the main procedure, often by the same provider in the same session. This allows for a more comprehensive representation of the services provided and recognizes the complexity and additional work that may be involved in performing the secondary procedure.

When coding, it is important to distinguish these procedures because they help accurately reflect the extent of the medical services rendered to a patient. Add-on codes are not intended to replace primary procedure codes, nor do they refer to unrelated services or modifications of existing codes. Their primary purpose is to enhance the coding of services when multiple related procedures occur in a single encounter.