CO-22 Denial Code: Care May Be Covered by Another Payer (Coordination of Benefits)

What Does CO-22 Mean?

CO-22 means the payer believes another insurance is primary for this patient, and you billed the wrong payer first — or the patient's coordination of benefits (COB) information on file is outdated. The claim will not pay until the primary/secondary order is straightened out.

Code group: CO (Contractual Obligation) · Appealable: Yes — once COB is corrected with the payer, request reprocessing rather than resubmitting fresh (protects timely filing).

Why CO-22 Happens

The patient has two coverages (common: employer plan + spouse's plan, or Medicare + employer coverage) and the payer's COB file says the other one is primary.
The patient's COB information is stale — they retired, changed jobs, or divorced, and never updated either insurer. The payer denies everything until the patient confirms COB.
Medicare Secondary Payer (MSP) situations: working aged, auto accident/liability, workers' compensation — Medicare denies as secondary when its records show other coverage.
An old policy that terminated still shows as active primary in the payer's system.

How to Fix a CO-22 Denial — Step by Step

Verify with the patient which coverages exist and which is primary. For dependents and dual coverage, the 'birthday rule' typically decides for children; the subscriber's own plan is primary for adults.

Have the patient call the denying payer to update COB — payers usually will not accept COB updates from the provider alone, and this single phone call resolves most CO-22 denials.

Bill the correct primary payer. Once it pays, submit to the secondary with the primary EOB attached.

If the denying payer is actually primary (their file is wrong), have the patient correct COB, then request reprocessing of the original claim — get a reference number.

Watch timely filing on the true primary — COB confusion does not extend most filing deadlines, though many payers accept proof of the original denial as grounds for an exception.

CO-22 Appeal Letter Template

Adapt this wording to your claim — replace the bracketed fields and attach the documentation it references:

Our claim was denied under CO-22 indicating other primary coverage. The patient has confirmed with your enrollment department on [date, reference #] that [Payer] is the primary payer for the date of service. We request reprocessing of claim [number] as primary. The patient's COB update is on file with your plan.

How to Prevent CO-22

Ask about other coverage at every check-in, not just new-patient visits.
Run eligibility checks that return COB data before the visit.
For Medicare patients, complete the MSP questionnaire at required intervals.

Related Denial Codes

CO-109 — Wrong payer/contractor CO-29 — Timely filing CO-16 — Missing information

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Reviewed by the LegitMedBilling denial management team. This guide is general billing information, not legal or payer-specific advice — always verify against your payer contract and current policy.

Frequently Asked Questions

The patient swears they only have one insurance. Now what?

The denying payer's COB file still shows other coverage — often a terminated plan. The patient must call the payer and confirm they have no other active coverage; the payer then updates COB and can reprocess the claim. Providers usually cannot make this update on the patient's behalf.

Which insurance is primary when a patient has two plans?

For the patient's own coverage: their employer plan is primary over a spouse's plan. For children: the birthday rule — the parent whose birthday falls earlier in the calendar year holds the primary plan. Medicare primacy depends on employer size and the reason for entitlement.

Does CO-22 mean the claim is denied forever?

No — it is a payable claim stuck behind a paperwork problem. Once COB is updated, ask for reprocessing of the existing claim. These denials have one of the highest recovery rates of any denial type when worked promptly.