CPT codes 90847 and 90846 are both used for family psychotherapy services provided by mental health professionals, but they differ in whether or not the patient is present during the session.
CPT code 90846 is used for family psychotherapy sessions without the patient present. This code is used when the therapist is working with the family members to address issues that affect the family as a whole, but the identified patient is not present during the session.
CPT code 90847, on the other hand, is used for family psychotherapy sessions with the patient present. This code is used when the therapist is working with the family members to address issues that affect the family as a whole, and the identified patient is present during the session.
In summary, the main difference between CPT codes 90847 and 90846 is whether or not the identified patient is present during the family psychotherapy session. Mental health professionals must use the appropriate code based on whether or not the patient is present to ensure accurate billing and reimbursement.