A biller will attach this two character descriptor to a code to further explain any changes in the service?

The two-character descriptor attached to a code by a biller is known as a modifier. Modifiers provide additional context about the service performed, indicating any variations or changes such as whether a procedure was altered, repeated, or performed on different body parts. This helps ensure accurate billing and reflects the specific circumstances of the service rendered. Proper use of modifiers can prevent claim denials and ensure appropriate reimbursement.