What is the denial code for other insurance primary?

CO-22. The payer believes another insurer is primary under coordination of benefits rules and wants that insurer to adjudicate first. Bill the primary payer, then send this payer the claim with the primary's remittance attached - the resulting adjustment typically posts as OA-23.

What is the denial code for billing the wrong payer?

Usually CO-109: the payer does not administer the patient's benefits for this service. Common causes are a Medicare claim sent to the wrong Medicare Administrative Contractor, a Medicaid managed care member billed to the state fee-for-service program, or a carved-out benefit such as behavioral health billed to the medical plan.

Coordination of benefits denial codes

These codes all say the money should come from somewhere else - or already partly has. CO-22 means this payer believes another insurer is primary and should adjudicate first. OA-23 is what a secondary payer posts after the primary has paid, adjusting for what the primary already allowed or paid. CO-109 means this payer does not administer the patient's benefits for the service at all, CO-19 that the injury belongs to a workers' compensation carrier, and CO-24 that a capitated group or managed care plan - often a Medicare Advantage plan - holds the risk for this member.

Also described as: other insurance is primary; COB; billed the wrong payer; workers' compensation; Medicare Advantage plan on file; secondary claim adjustment.

The 5 codes and what separates them

CO-22 - Care may be covered by another payer per coordination of benefits
The payer believes another insurer is primary for this patient and wants that insurer to adjudicate first.
Who pays: Another payer
OA-23 - Impact of prior payer's adjudication
This payer reduced its payment to account for what the primary payer already allowed or paid. Expected on secondary claims.
Who pays: Neither - adjustment
CO-109 - Claim not covered by this payer or contractor
This payer or contractor does not handle the patient's benefits for this service - the claim went to the wrong entity.
Who pays: Another payer
CO-19 - The claim belongs to a work-related injury carrier
The plan has determined the treatment relates to a work injury, which belongs to the workers' compensation carrier.
Who pays: Workers' comp carrier
CO-24 - Charges are covered under a capitation or managed care arrangement
The member's benefits for this service run through a capitated group or managed care plan, so this payer is not the one that pays.
Who pays: Another payer

How to tell which one you have

If the remittance shows another carrier's payment already factored in, it is OA-23 and there is usually nothing to fix. For CO-22, find out which plan the payer has on file as primary - the patient often has to update their coordination of benefits record with the payer before anything reprocesses. CO-109 and CO-24 mean the claim belongs with a different entity; for CO-24 that is usually the patient's Medicare Advantage plan or capitated medical group. CO-19 needs either the workers' compensation claim details or documentation that the condition is not work related.

Frequently asked questions

What is the denial code for other insurance primary?: CO-22. The payer believes another insurer is primary under coordination of benefits rules and wants that insurer to adjudicate first. Bill the primary payer, then send this payer the claim with the primary's remittance attached - the resulting adjustment typically posts as OA-23.
What is the denial code for billing the wrong payer?: Usually CO-109: the payer does not administer the patient's benefits for this service. Common causes are a Medicare claim sent to the wrong Medicare Administrative Contractor, a Medicaid managed care member billed to the state fee-for-service program, or a carved-out benefit such as behavioral health billed to the medical plan.

Other denial reasons

Out of network No prior authorization Not medically necessary Service not covered Bundled or not paid separately Coding mismatch or invalid code Patient not eligible or coverage ended Missing information, duplicate, or late filing Provider not eligible or not credentialed Benefit or unit limit reached Deductible, coinsurance, or copay Paid less than billed

Every denial code in one table

Last reviewed October 3, 2026.

These are original plain-English summaries written for reference, not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.