I receive many questions on the use of modifier 59 for outpatient therapy services. A few common questions I receive are “What is the definition of modifier 59?, When can I use modifier 59?” and my favorite “I have been told by my billing people that I can only use modifier 59 if I see the patient for 2 visits on the same day, not during a single visit, is that true?” I am going to answer the above 3 questions plus provide you with a document from the Centers for Medicare and Medicaid Services (CMS) that will support my answers and you can share with those back in your practice and organization.

The definition of modifier 59 is as follows: