What modifier is used for 99391?

The modifier commonly used for CPT code 99391, which refers to a preventive medicine evaluation and management visit for a new patient, is often modifier 25. This modifier indicates that a significant, separately identifiable evaluation and management service was performed on the same day as another service. However, the specific modifier to use can vary based on the context of the visit and the services provided, so it's essential to consult payer guidelines for accurate billing.