The most common medical billing denial codes in 2026 include CO-16, CO-22, CO-29, CO-50, CO-96, CO-97, and CO-197. They typically point to problems such as missing claim information, coordination of benefits, timely filing, medical necessity, non-covered services, bundling, and missing prior authorization. The exact action required depends on the payer’s remittance advice and the details of the claim.
What Do These Denial Codes Mean?
Here are the denial codes medical practices are most likely to encounter:
| Code | Common Meaning | Typical Problem |
|---|---|---|
| CO-16 | Missing or invalid information | Required patient, provider, or claim information is missing or incorrect |
| CO-22 | Coordination of benefits | Another insurance may be responsible for primary payment |
| CO-29 | Timely filing | Claim was submitted after the payer’s filing deadline |
| CO-50 | Medical necessity | Payer determines the service is not supported by its medical-necessity requirements |
| CO-96 | Non-covered charge | Service is excluded from the patient’s applicable benefit |
| CO-97 | Included in another service | Payer considers the service included in another billed procedure |
| CO-197 | Prior authorization | Required authorization or precertification was not obtained or was invalid |
| CO-11 | Diagnosis/procedure mismatch | Diagnosis does not support the billed procedure under payer rules |
What Is CO-16 in Medical Billing?
CO-16 means the claim contains missing or invalid information needed for processing. It can involve patient demographics, subscriber information, provider details, or other required claim data.
The billing team should review the payer’s remittance advice to determine exactly what information needs correction before submitting a corrected claim.
What Is CO-29?
CO-29 means the claim was submitted after the payer’s timely filing limit. The practice should verify the payer’s filing deadline and determine whether documentation supports a timely-filing exception or appeal.
This is why claims should be monitored from submission through adjudication rather than simply submitted and forgotten.
What Is CO-50?
CO-50 indicates a medical-necessity issue. The payer has determined that the billed service does not meet the applicable medical-necessity requirements.
Before appealing, review the patient’s documentation, diagnosis coding, procedure coding, and the payer’s medical policy to determine whether the claim is adequately supported.
What Is CO-97?
CO-97 generally means the payer considers the billed service included in another service or procedure. This is commonly associated with bundling or payment-policy rules.
The billing team should review the CPT codes, modifiers, documentation, and payer policy before making a correction.
What Is CO-197?
CO-197 indicates that required prior authorization or precertification was not obtained or was not valid for the billed service.
Common causes include an expired authorization, incorrect procedure, wrong provider or location, or authorization for fewer units than were billed.
Practices can reduce these denials by verifying authorization requirements before treatment and maintaining an authorization record for each applicable service.
What Are CO-22, CO-96, and CO-11?
CO-22: Another payer may be responsible for the claim first, requiring a coordination-of-benefits review.
CO-96: The payer considers the charge non-covered under the applicable benefit. The practice should verify the patient’s actual benefits before determining responsibility.
CO-11: The diagnosis submitted with the procedure does not meet the payer’s requirements for supporting that service. Coding and documentation should be reviewed before correction or appeal.
How Can Medical Practices Prevent These Denials?
Most denial prevention starts before the claim is submitted:
Verify eligibility → Confirm authorization → Review documentation → Code accurately → Scrub the claim → Submit → Track the claim
For example, eligibility verification can help identify inactive coverage or coordination-of-benefits issues before services are provided. Claim review and coding controls can address other preventable errors.
For practices with recurring denial problems, revenue cycle management can connect eligibility, coding, claims, payment posting, and A/R follow-up into one workflow.
Should Every Denial Be Resubmitted?
No. The correct response depends on the denial.
A practice may need to:
- Correct and resubmit the claim
- Submit an appeal
- Provide medical records
- Contact the payer for reprocessing
- Bill the correct primary payer
- Review coding or documentation
- Accept an appropriate contractual adjustment
Automatically resubmitting a denied claim without identifying the cause can create duplicate claims and additional delays.
How Can a Practice Identify Its Most Common Denial Code?
Review denial data by payer, denial code, CPT/HCPCS code, ICD-10 code, provider, location, and date of service.
For example, if CO-197 repeatedly occurs for the same procedure, the underlying problem may be a missing authorization workflow rather than a problem with the billing software.
A medical billing audit can also help identify recurring coding, documentation, eligibility, and claim-processing issues.
What Is the Quickest Way to Understand a Denial?
Start with the ERA or EOB, identify the adjustment reason and any accompanying remark codes, then compare the payer’s explanation with the submitted claim.
Do not rely on the denial code alone. The payer’s full message, claim details, medical documentation, and applicable policy determine what action should be taken.
The Medicator’s provides medical billing services and RCM support for practices dealing with eligibility, claims, denials, and A/R workflows. You can also visit The Medicator’s for additional medical billing resources.
FAQ Quick Answer
What are the most common denial codes in 2026?
CO-16, CO-22, CO-29, CO-50, CO-96, CO-97, CO-197, and CO-11 are common examples involving missing information, coordination of benefits, timely filing, medical necessity, non-covered services, bundling, authorization, and diagnosis-procedure issues.
Which denial code indicates missing information?
CO-16 generally indicates that required claim information is missing or invalid.
Which denial code indicates timely filing?
CO-29 generally indicates that the claim was submitted after the payer’s filing deadline.
Which denial code indicates prior authorization problems?
CO-197 is commonly associated with required prior authorization or precertification not being obtained or not being valid.
Which denial code is associated with medical necessity?
CO-50 is commonly associated with medical-necessity determinations.
Can denial codes change by payer?
The standardized adjustment codes provide a common framework, but payer-specific policies, remark codes, and processing rules can affect how a denial is explained and what corrective action is required.
