What is modifier 26 use for in medical coding?

Modifier 26 is appended to the primary procedure code of a claim form when the professional service is performed in addition to the primary procedure on the same day, by the same physician.

26 Professional service performed by the same physician on the same day as, but independent and unrelated to, the primary service or procedure.

For example, if a patient comes to the office for an initial consultation and then the physician decides to perform a biopsy on the same day, the physician would use modifier 26 on the biopsy procedure code.