Anesthesia modifier with example – Modifier description


Modifiers are two-digit indicators used to modify payment of a procedure code, assist in determining appropriate coverage or otherwise identify the detail on the claim. Every anesthesia procedure billed to Medicare must include one of the following anesthesia modifiers: AA, QY, QK, AD, QX or QZ. The other modifiers listed below may be used to identify specific situations in addition to the required modifiers

An anesthesiologist is personally performing the anesthesia service to the patient and he administered Monitored Anesthesia Care (MAC). The modifiers billed to Medicare would be AA and QS consecutively.

(Do not use the following modifiers if the provider of service is a CRNA or AA.)

Modifier Description

AA Anesthesia services personally performed by the anesthesiologist
QY Medical direction of one CRNA by an anesthesiologist
QK Medical direction of two, three or four concurrent anesthesia procedures
AD Supervision, more than four procedures

(Do not use the following modifiers if the provider of service is an Anesthesiologist.)

Modifier Description
QX Anesthesia, CRNA medically directed
QZ Anesthesia, CRNA not medically directed


Modifier Description

QS Monitored Anesthesia Care (MAC) services (can be billed by a CRNA, AA or physician)
G8 Monitored Anesthesia Care (MAC) for deep complex, complicated or markedly invasive surgical procedure

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