The correct answer is: Modifier Code 25
CPT code modifiers are used to adjust care descriptions and to provide extra details about the procedure or service provided by a physician in order to help better describe of a procedure without changing its definition. Modifiers are required to clarify how things should be paid.
Modifier Code 25 is used to identify separately identifiable evaluation and management services (well child check) performed by the same physician on the same day as a procedural service (immunization).