DENIAL CODE · CO-109

CO-109: Not Covered by This Payer

CO-109 means the claim went to the wrong payer — often a Medicare Advantage or managed plan when the claim was sent to traditional Medicare, or the wrong entity entirely.

Official (X12/WPC): "Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor."

Why payers issue CO-109

  • The patient is enrolled in a Medicare Advantage or managed plan, not the payer billed
  • Eligibility wasn't verified to the current plan
  • The wrong payer ID routed the claim
  • Coverage moved and the old payer was billed

Is it recoverable? Recoverable by identifying and rebilling the correct payer — verify the active plan for the date of service.

Common questions

What does CO-109 mean?

CO-109 means the claim went to the wrong payer — often a Medicare Advantage or managed plan when the claim was sent to traditional Medicare, or the wrong entity entirely. Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor.

How do I appeal or fix a CO-109 denial?

Recoverable by identifying and rebilling the correct payer — verify the active plan for the date of service. Common causes: the patient is enrolled in a Medicare Advantage or managed plan, not the payer billed; eligibility wasn't verified to the current plan; the wrong payer ID routed the claim; coverage moved and the old payer was billed.

Is a CO-109 denial worth appealing?

Recoverable by identifying and rebilling the correct payer — verify the active plan for the date of service. 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-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-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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