HCPCS Modifier AA

Published 07/16/2020

HCPCS Modifier AA — anesthesia Services performed personally by the anesthesiologist.

Guidelines and Instructions
  • This modifier may only be submitted with anesthesia procedure codes (e.g., CPT codes 00100 through 01999)
  • Payment for services that meet the definition of personally performed is based on the base units (as defined by CMS) and time in increments of 15-minute units
In the following situations, the anesthesia service is considered personally performed:
  • The physician personally performed the entire anesthesia service alone
  • The physician is involved with one anesthesia case with a resident, and the physician is a teaching physician
    • For the definition of a teaching physician, refer to the CMS website (PDF, 1.10 MB) Pub. 100-04, Chapter 12, Section 100
  • The physician is involved in the training of physician residents in a single anesthesia case, two concurrent anesthesia cases involving residents or a single anesthesia case involving a resident that is concurrent to another case that meets the requirements for payment at the medically directed rate. The physician meets the teaching physician criteria in IOM Pub. 100-04, Chapter 12, Section 100.1.4
  • The physician is continuously involved in a single case involving a student nurse anesthetist
  • The physician and one Certified Registered Nurse Anesthetist (CRNA) or anesthesiologist's assistant (AA) are involved in one anesthesia case and the services of each are medically necessary
    • Documentation must be submitted by both the physician and the CRNA or AA to support medical necessity and to allow reimbursement at the personally performed rate
    • In these situations, the physician must submit the anesthesia service with HCPCS modifier AA (personally performed)
      • The CRNA must submit the anesthesia service with HCPCS modifier QZ (not medically directed)
      • The AA may only submit anesthesia services with HCPCS modifier QX (medically directed) 

Reference: CMS Pub. 100-04, Chapter 12, Section 50.I Anesthesia Claims Modifiers (PDF, 1.10 MB).

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