DENIAL CODE · CO-181

CO-181: Procedure Code Invalid on Date of Service

CO-181 means the CPT/HCPCS code billed wasn't valid on the date of service — usually a code that was deleted, replaced, or not yet active for that year.

Official (X12/WPC): "Procedure code was invalid on the date of service."

Why payers issue CO-181

  • The code was retired or replaced in the annual CPT/HCPCS update
  • A new-year code was billed for a prior-year date (or vice versa)
  • A typo produced an invalid code
  • The code wasn't effective yet on the date of service

Is it recoverable? Recoverable — map to the correct effective-dated code for that date of service and resubmit as a corrected claim.

How to appeal a Missing or Invalid Information denial →

Common questions

What does CO-181 mean?

CO-181 means the CPT/HCPCS code billed wasn't valid on the date of service — usually a code that was deleted, replaced, or not yet active for that year. Procedure code was invalid on the date of service.

How do I appeal or fix a CO-181 denial?

Recoverable — map to the correct effective-dated code for that date of service and resubmit as a corrected claim. Common causes: the code was retired or replaced in the annual CPT/HCPCS update; a new-year code was billed for a prior-year date (or vice versa); a typo produced an invalid code; the code wasn't effective yet on the date of service.

Is a CO-181 denial worth appealing?

Recoverable — map to the correct effective-dated code for that date of service and resubmit as a corrected claim. 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-54 · Assistant Surgeon Not Covered →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-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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