HCPCS Modifier O

Published 07/16/2020

Physician’s Office (Only for ET3 Model Claims).

Guidelines and Instructions

  • Submit this modifier to indicate the destination of an ambulance transport for an ET3 model ambulance claim when the location is a physician’s office  
  • Additional documentation may be required to support the need for this ambulance trip 


  • CMS Emergency Triage, Treat, and Transport (ET3) Model web page
  • CMS Ambulance website

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