On an insurance claim, there are the diagnosis codes (these are the diagnosis codes for the patient) in BOX 21 and there are the diagnosis pointers (where you point to diagnosis codes (from Box 21). The diagnosis pointers (known as treatment diagnosis in Therabill) are entered on the service lines (Box 24 on the CMS-1500) for each service in Box 24E.
You can only point to up to four diagnosis (diagnosis pointers or treatment diagnosis) for a service line on the claim. This rejection is an indication that you have pointed to more than four diagnosis codes.
How to fix
Open up the edit session form for the session(s) on this claim. Underneath the service code section, make sure only (up to) four diagnosis codes are checked. These are the treatment diagnosis (you can only select up to four). Remember to save.
There were less than four treatment diagnosis on the edit session form
This can happen if, at the time you created the session, you had more than four diagnosis associated with the patient. When this happens, you may have created the session and the session was pointing to more than four. Changing the diagnosis codes of the patient (i.e. removing some) does not update the sessions. Therefore, if this is the case, all you have to do is save the session. Saving the session will update the treatment diagnosis pointers.