CO-33 Denial Code Explained

CO-33 is a medical billing denial code that indicates the claim cannot be processed because coordination of benefits information is incomplete or incorrect. This denial commonly occurs when multiple insurance plans are involved.

What Does CO-33 Mean?

The CO-33 denial code means the insurance payer requires updated coordination of benefits information before processing the claim.

This denial is often related to payer sequencing issues, missing insurance details, or outdated eligibility records.

Common Reasons for CO-33

• Missing secondary insurance information

• Incorrect primary payer billing

• Coordination of benefits conflicts

• Outdated patient insurance records

• Duplicate insurance coverage

• Incorrect payer sequencing

How To Fix CO-33

Verify the patient’s insurance coverage and confirm the correct primary and secondary payer order. Update coordination of benefits information and resubmit the claim with accurate payer details.

Providers may also need to obtain updated COB documentation directly from the patient or insurance payer.

Related Denial Codes

You may also encounter:

• CO-22 — Coordination of benefits issue

• CO-23 — Prior payer adjustment information required

• CO-20 — Another payer may be responsible

• CO-27 — Coverage terminated before service date

Quick Summary

CO-33 indicates the payer requires updated coordination of benefits information before the claim can be processed. Most denials are related to payer sequencing or incomplete insurance details.

Medical billing denial codes, insurance prefixes, and claim guidance in one searchable resource hub.

© 2026. All rights reserved.

Quick Links

Denial Codes

BCBS Prefixes

Articles

Resources

About ClariMed

Terms and Conditions

Privacy Policy