What is the age limit for CPT code 99391?

CPT code 99391 (visit complexity requiring medically appropriate history and/or examination and decision-making) does not have an age limit.

However, it is typically used for patients ages 18 and over. For patients under the age of 18, CPT codes 99201-99215 (New Patient Office Visit) or 99211-99215 (Established Patient Office Visit) may be used instead.