An Add-on Code (AOC) is a Healthcare Common Procedure Coding System (HCPCS) / Current Procedural Terminology (CPT) code that describes a service that is performed in conjunction with the primary service by the same practitioner. An AOC is rarely eligible for payment if it’s the only procedure reported by a practitioner.
Add-on codes may be identified in three ways:
CMS divided the AOCs into three types to distinguish the payment policy for each type:
A Type 1 AOC has a limited number of identifiable primary procedure codes. The Change Request (CR) lists the Type 1 AOCs with their acceptable primary procedure codes. A Type 1 AOC, with one exception, is eligible for payment if one of the listed primary procedure codes is also eligible for payment to the same practitioner for the same patient on the same date of service. Claims processing contractors must adopt edits to assure that Type 1 AOCs are never paid unless a listed primary procedure code is also paid.
A Type 2 AOC does not have a specific list of primary procedure codes. The CR lists the Type 2 AOCs without any primary procedure codes. Claims processing contractors are encouraged to develop their own lists of primary procedure codes for this type of AOC. Like the Type 1 AOCs, a Type 2 AOC is eligible for payment if an acceptable primary procedure code as determined by the claims processing contractor is also eligible for payment to the same practitioner for the same patient on the same date of service.
A Type 3 AOC has some, but not all, specific primary procedure codes identified in the CPT Manual. The CR lists the Type 3 AOCs with the primary procedure codes that are specifically identifiable. However, claims processing contractors are advised that these lists are not exclusive and there are other acceptable primary procedure codes for AOCs in this Type. Claims processing contractors are encouraged to develop their own lists of additional primary procedure codes for this group of AOCs. Like the Type 1 AOCs, a Type 3 AOC is eligible for payment if an acceptable primary procedure code as determined by the claims processing contractor is also eligible for payment to the same practitioner for the same patient on the same date of service.
CMS will update the complete list of AOC edits on an annual basis on or by Jan. 1 based on changes to the CPT Manual or HCPCS Level II Manual. CMS may post quarterly updates on April 1, July 1, and Oct. 1 of each year. If CMS provides quarterly updates, they are complete files of AOC edits. If there are no changes in the AOC edits, then there is no quarterly update.
