DENIAL CODE · CO-54

CO-54: Assistant Surgeon Not Covered

CO-54 means the payer denied the assistant surgeon (or additional physician) as not covered for this procedure. Whether it sticks depends on whether the procedure allows an assistant under the payer's own rules.

Official (X12/WPC): "Multiple physicians/assistants are not covered in this case."

Why payers issue CO-54

The procedure isn't on the payer's assistant-surgeon-eligible list
The assistant modifier (80/81/82/AS) was missing or wrong
Documentation didn't establish the assistant's medical necessity
The payer's edit is stricter than CMS's assistant-at-surgery indicators

Is it recoverable? Recoverable when CMS or the payer's own indicators allow an assistant for that CPT — the appeal cites the eligibility indicator and documents the assistant's role.

Recover a Modifier Payment Reductions (Bilateral, Assistant, Co-Surgeon) underpayment →

Common questions

What does CO-54 mean?

How do I appeal or fix a CO-54 denial?

Recoverable when CMS or the payer's own indicators allow an assistant for that CPT — the appeal cites the eligibility indicator and documents the assistant's role. Common causes: the procedure isn't on the payer's assistant-surgeon-eligible list; the assistant modifier (80/81/82/AS) was missing or wrong; documentation didn't establish the assistant's medical necessity; the payer's edit is stricter than CMS's assistant-at-surgery indicators.

Is a CO-54 denial worth appealing?

Recoverable when CMS or the payer's own indicators allow an assistant for that CPT — the appeal cites the eligibility indicator and documents the assistant's role. You only pay on what's actually recovered, so there's no cost to working the ones that are winnable.

Other denial codes

CO-197 · Precertification / Authorization Absent →CO-50 · Not Medically Necessary →CO-16 · Missing or Invalid Information →CO-45 · Charge Exceeds Fee Schedule →CO-97 · Bundled into Another Service →CO-29 · Timely Filing Expired →CO-96 · Non-Covered Charge →OA-18 · Duplicate Claim →OA-22 · Coordination of Benefits →CO-11 · Diagnosis Inconsistent with Procedure →CO-151 · Too Many Services (Frequency/MUE) →CO-B7 · Provider Not Eligible →CO-27 · Coverage Terminated →CO-204 · Not Covered Under Current Plan →CO-109 · Not Covered by This Payer →CO-119 · Benefit Maximum Reached →CO-4 · Modifier Inconsistent or Missing →CO-15 · Authorization Number Missing or Invalid →OA-23 · Prior Payer Adjudication Impact →CO-24 · Charges Covered Under Capitation →CO-26 · Expenses Incurred Prior to Coverage →CO-55 · Experimental / Investigational →CO-58 · Inappropriate Place of Service →CO-59 · Multiple/Concurrent Procedure Reduction →CO-107 · Related/Qualifying Claim Not Identified →CO-167 · Diagnosis Not Covered →CO-170 · Denied for This Provider Type →CO-181 · Procedure Code Invalid on Date of Service →CO-182 · Procedure Modifier Invalid on Date of Service →CO-183 · Referring Provider Not Eligible to Refer →CO-185 · Rendering Provider Not Eligible →CO-198 · Precertification / Authorization Exceeded →CO-226 · Requested Provider Information Not Provided →CO-231 · Mutually Exclusive Procedures →CO-234 · Procedure Not Paid Separately →CO-236 · Procedure/Modifier Combination Not Compatible →CO-242 · Out-of-Network / Non-Network Provider →CO-252 · Documentation Required to Adjudicate →CO-253 · Sequestration Reduction →CO-256 · Not Payable Per Managed-Care Contract →CO-288 · Referral Absent →CO-B15 · Qualifying Service Not Received →CO-B16 · New Patient Qualifications Not Met →CO-A1 · Claim/Service Denied (Remark Required) →

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