Denial Codes

The CO-1 denial code ties reason code 1 (deductible) to the Contractual Obligation group. Learn why a deductible normally belongs to PR-1, when CO-1 signals an error, and how to verify it.

The CO-109 denial code means the claim is not covered by this payer and must go to the correct one. Learn how to find the right payer, rebill, and prevent CO-109.

The CO-11 denial code means the diagnosis is inconsistent with the procedure. Learn why the ICD-10 to CPT linkage fails, how coverage policy drives it, and how to correct and appeal it.

The CO-119 denial code means the benefit maximum for the period has been reached and the excess is a contractual write-off. Learn how the KX threshold drives it and when to appeal.

The CO-12 denial code means the diagnosis is inconsistent with the provider type. Learn how specialty and taxonomy edits trigger it, how it differs from CO-8, and how to resolve it.

The CO-140 denial code means the patient's health ID number and name do not match the payer's records. Learn what data errors trigger it and how to fix and prevent it.

The CO-15 denial code means the authorization number is missing, invalid, or does not apply to the billed service. Learn what triggers it and how to fix and prevent it.

The CO-151 denial code means the payer says the information submitted does not support this many services. Learn why units and frequency get cut, and how to appeal a CO-151 adjustment.

The CO-16 denial code means your claim lacks information or has a billing error. Learn how to read the remark code, fix the missing data, and resubmit to get paid.

The CO-18 denial code flags an exact duplicate claim under the Contractual Obligation group. Learn why it appears instead of OA-18, how to spot false duplicates, and how to resolve it.

The CO-182 denial code means the procedure modifier was invalid on the date of service. Learn how retired or wrong modifiers trigger it and how to correct and refile the claim.

The CO-197 denial code means precertification or authorization was absent. Learn when retro-authorization is possible, how to appeal, and how to prevent CO-197.

The CO-2 denial code ties reason code 2 (coinsurance) to the Contractual Obligation group. Learn why coinsurance normally belongs to PR-2, when CO-2 signals an error, and how to check it.

The CO-204 denial code means a service isn't covered under the plan and the cost is a provider write-off. Learn how it differs from PR-204, what triggers it, and how to recover it.

The CO-22 denial code means the care may be covered by another payer under coordination of benefits. Learn how to fix the COB order and rebill to the right payer.

The CO-222 denial code means the claim exceeds the contracted maximum hours, days, or units for the provider this period. Learn why it happens and how to fix and appeal it.

The CO-23 denial code carries a prior payer's adjudication onto a secondary claim. Learn what it means, why the CO vs OA group matters, and how to verify or appeal it.

The CO-234 denial code means the procedure is not paid separately. Learn why a service gets bundled, when a modifier can unbundle it, and how to respond to a CO-234 adjustment.

The CO-24 denial code means charges are covered under a capitation agreement or managed care plan. Learn why capitated claims land here, who to bill instead, and how to correct it.

The CO-252 denial code means additional documentation is required to adjudicate the claim. Learn which records to send, how to read the remark code, and how to respond.

The CO-253 denial code is the Medicare sequestration adjustment — a 2% reduction in federal payment. Learn why it appears, that it is not a true denial, and how to handle it.

The CO-26 denial code means expenses were incurred before the patient's coverage began. Learn what effective-date issues trigger it, how it differs from CO-27, and how to resolve it.

The CO-27 denial code means expenses were incurred after the patient's coverage terminated. Learn why active-on-the-date coverage fails, who pays, and how to verify and resubmit.

The CO-272 denial code means the service did not meet the payer's coverage or program guidelines. Learn why it happens, how to find the cited policy, and how to appeal it.

The CO-29 denial code means the time limit for filing the claim has expired. Learn the timely filing rules, how to appeal with proof, and how to prevent CO-29 denials.

The CO-3 denial code ties reason code 3 (copayment) to the Contractual Obligation group. Learn why a copay normally belongs to PR-3, when CO-3 signals an error, and how to confirm it.

The CO-4 denial code means the procedure code is inconsistent with the modifier used, or a required modifier is missing. Learn how to correct the modifier and rebill.

The CO-40 denial code means charges do not meet the qualifications for emergent or urgent care. Learn what triggers it, how documentation drives the appeal, and how to resolve it.

The CO-45 denial code means your charge exceeds the payer's allowed amount. Learn why it happens, whether you can bill the patient, and how to appeal underpayments.

The CO-49 denial code means the service is a non-covered routine or preventive exam or screening. Learn what triggers it, the preventive-coverage exceptions, and how to resolve it.

The CO-5 denial code means the procedure code or bill type is inconsistent with the place of service. Learn why it happens, how it differs from CO-58, and how to fix it.

The CO-50 denial code means the payer deems the service not medically necessary. Learn why it happens, how LCD/NCD and diagnosis coding drive it, and how to build a strong appeal.

The CO-55 denial code means the payer deems a procedure, treatment, or drug experimental or investigational. Learn what drives it, the evidence an appeal needs, and how to fix it.

The CO-58 denial code means the payer judged the service rendered in an inappropriate or invalid place of service. Learn why it happens, how it differs from CO-5, and how to fix it.

The CO-59 denial code means a claim was processed under multiple or concurrent procedure rules, often an MPPR reduction. Learn why it happens, how MPPR works, and when to appeal.

The CO-8 denial code means the procedure billed is inconsistent with the provider's type, specialty, or taxonomy. Learn the common causes, the credentialing link, and how to fix it.

The CO-9 denial code means the diagnosis is inconsistent with the patient's age. Learn what age-edit triggers it, how it differs from other diagnosis mismatches, and how to fix it.

The CO-96 denial code means non-covered charges under the contract. Learn how to read the remark code, when CO-96 is appealable, and why you can't bill the patient.

The CO-97 denial code means the service is bundled into another payment already made. Learn when bundling is correct, when a modifier unbundles it, and how to appeal.

The OA-18 denial code flags a claim or service as an exact duplicate of one already submitted. Learn what triggers it, how to tell a true duplicate from a false one, and how to resolve it.

The OA-23 denial code shows the impact of a prior payer's adjudication on a secondary claim. Learn what it means, why it's not a true denial, and how to verify it.

The PR-1 denial code means the amount was applied to the patient's deductible. Learn why it is patient responsibility, how it differs from a true denial, and how to handle it cleanly.

The PR-119 denial code means the benefit maximum for the time period or occurrence has been reached. Learn what caps trigger it, why it becomes patient responsibility, and how to respond.

The PR-2 denial code is the coinsurance amount the patient owes after the plan pays. Learn why it is not a true denial, how it differs from a deductible, and how to handle it.

The PR-204 denial code means the service isn't covered under the patient's current benefit plan and is patient responsibility. Learn when to bill the patient or appeal.

The PR-3 denial code means the amount is the patient's copayment. Learn why it is patient responsibility, how it differs from a deductible, and how to collect it cleanly.

The PR-31 denial code means the patient cannot be identified as the payer's insured. Learn why eligibility checks fail, how to verify and correct member data, and how to resubmit.

The PR-49 denial code means a service is non-covered as a routine or preventive exam or screening. Learn why it happens, when it is a coding fix, and when to appeal or bill the patient.

The PR-96 denial code means non-covered charges that are patient responsibility. Learn when you can bill the patient, the notice rules, and how to handle PR-96.