CO-22 — Coordination of Benefits (COB) — Another Payer May Be Primary (CO-22)
CARC 22 means the payer believes another plan may be primary for this care, or the claim did not carry the prior payer's information. This is a payer-order and COB-data finding. It is a different finding from CARC 23, which reports the impact of a prior payer's adjudication.
Guided troubleshooter available for this denial
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In plain language
The payer believes another insurance plan should pay first (or already has), and either the claim didn't include that other payer's information/EOB, or the payer sequence on file is out of date.
Start here
Confirm the correct payer sequence with the patient and any available COB data.
Who resolves it
Billing/Follow-Up
Who prevents it
Registration/Patient Access — COB questionnaire completed and verified at every visit, not only at initial registration.
How to resolve this denial, step by step
- 1
Confirm the correct payer sequence with the patient and any available COB data.
- 2
Obtain the primary payer's EOB/remittance for the same date of service.
- 3
Submit/resubmit to the secondary payer with the primary EOB attached or COB loop populated.
- 4
If the payer's own COB records are wrong, contact the payer's COB unit or have the patient update it directly (commercial payers) or the state Medicaid COB unit.
- 5
Document COB status update.
- 6
Escalate if COB dispute persists across multiple claims.
Then choose the correct disposition
COB correction
most common; typically a corrected claim once the missing EOB/payer sequence is added.
Payer follow-up
needed when the payer's own COB file is outdated.
Formal appeal
only if the payer refuses to reprocess despite correct/updated COB documentation.
Stop and escalate when
- Payer and patient disagree on payer sequence; primary payer denies coverage entirely (may shift liability); repeated COB denials despite correct submission (potential payer processing error).
What Needs to Be Corrected
- Claim correction: Attach/enter the primary payer's EOB or 835 COB loop data and resubmit to the secondary payer.
- Upstream correction: Registration must update the COB questionnaire and payer sequence; if the payer's own COB file is wrong, the patient or provider must contact the payer to update it.
Do Not Do This
- Do not bill the patient for the balance while COB is unresolved.
- Do not submit the secondary claim without the primary EOB unless the payer's policy explicitly allows electronic COB without attachment.
- Do not treat CARC 22 as prior-payer impact (CARC 23) or as a provider-level recoupment — those are separate findings.
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