Top 10 Medical Billing Denial Codes Every Biller Should Know
Medical billing professionals encounter hundreds of denial codes, but a small number account for a large percentage of claim denials. Understanding these common denial codes helps providers resolve billing issues faster, improve reimbursement, and reduce future claim denials.
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5/12/20262 min read
Top 10 Medical Billing Denial Codes Every Biller Should Know
Medical billing professionals encounter hundreds of denial codes, but a small number account for a large percentage of claim denials. Understanding these common denial codes helps providers resolve billing issues faster, improve reimbursement, and reduce future claim denials.
Whether you're new to medical billing or an experienced biller, knowing these denial codes can significantly improve claim management and revenue cycle performance.
Why These Denial Codes Matter
Some denial codes appear far more frequently than others because they involve common billing mistakes such as missing information, eligibility issues, duplicate claims, and patient responsibility.
Learning these denial codes allows billing staff to identify problems quickly and take the appropriate corrective action.
1. CO-16 – Missing or Incomplete Information
One of the most common denial codes in medical billing.
This denial indicates the insurance company needs additional information before the claim can be processed.
Common causes include:
Missing documentation
Incomplete claim fields
Invalid patient information
Learn more: CO-16 Denial Code
2. CO-18 – Duplicate Claim or Service
CO-18 indicates the payer believes the service has already been submitted or processed.
Before resubmitting a claim, providers should verify the original claim status.
Learn more: CO-18 Denial Code
3. CO-22 – Coordination of Benefits Required
CO-22 occurs when the insurance company requires additional coordination of benefits (COB) information before processing payment.
Providers should verify primary and secondary insurance coverage before resubmitting the claim.
Learn more: CO-22 Denial Code
4. PR-1 – Deductible Amount
PR-1 indicates the patient's deductible applies to the billed service.
This amount is generally the patient's financial responsibility.
Learn more: PR-1 Denial Code
5. PR-2 – Coinsurance Amount
PR-2 identifies the portion of the claim that the patient must pay as coinsurance according to their insurance plan.
Learn more: PR-2 Denial Code
6. PR-3 – Copayment Amount
PR-3 indicates the patient is responsible for a required copayment under their health insurance policy.
Learn more: PR-3 Denial Code
7. PR-96 – Non-Covered Charges
PR-96 means the insurance plan does not cover the billed service.
Providers should review the patient's benefits before billing the patient.
Learn more: PR-96 Denial Code
8. OA-23 – Prior Payer Information
OA-23 generally indicates the claim has been adjusted based on another payer's payment or coordination of benefits information.
Providers should review previous payer adjudication before resubmitting claims.
Learn more: OA-23 Denial Code
9. OA-94 – Special Payment Policy
OA-94 indicates the claim was processed under a special Medicare or payer-specific payment policy.
Providers should review the remittance advice for additional details.
Learn more: OA-94 Denial Code
10. CO-123 – Authorization or Benefit Issues
CO-123 generally indicates payment was affected because authorization requirements or plan benefits were not met.
Providers should review the payer's explanation before determining whether a corrected claim or appeal is appropriate.
Learn more: CO-123 Denial Code
How To Reduce Common Denial Codes
Many of these denials can be prevented by:
Verifying insurance eligibility before every visit.
Reviewing patient demographics.
Confirming prior authorization requirements.
Checking claims for missing information.
Reviewing coding accuracy before submission.
Small improvements in claim accuracy can significantly reduce denial rates over time.
Frequently Asked Questions
Which denial code is most common?
CO-16 is one of the most frequently encountered denial codes because missing or incomplete claim information is a common billing issue.
Should every denial be appealed?
No. Some denials require corrected claims rather than formal appeals.
Can providers prevent most denial codes?
Many denial codes can be reduced through proper insurance verification, accurate coding, complete documentation, and careful claim review before submission.
Where can I learn more about a specific denial code?
Each denial code has its own dedicated guide explaining its meaning, common causes, and recommended next steps.
Related Articles
What Is A Claim Adjustment Reason Code (CARC)?
How To Read Medical Billing Denial Codes
Understanding CARC and RARC Codes
How To Reduce Medical Billing Claim Denials
Quick Summary
Although hundreds of medical billing denial codes exist, a small group appears most frequently during claim processing. Understanding common denial codes such as CO-16, CO-18, CO-22, PR-1, PR-2, PR-3, PR-96, OA-23, OA-94, and CO-123 helps healthcare providers resolve claims more efficiently and improve reimbursement outcomes.
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