Notes on payer behavior

CO-22 denial code: another payer may be responsible

Clearia · September 2026 · denial codes, read properly

Denial code CO-22 is the payer saying: "This care may be covered by another payer per coordination of benefits." What that means for your practice, and whether it's worth chasing, below.

What the payer is asserting

CO-22 is not a judgment about the care or the coding. It's the payer saying "not me first." Their records show the patient has other coverage, or a questionnaire on file says the visit may relate to an accident or a job, and they won't pay until the primary payer has. Nothing has been decided about the money. The claim is parked.

Where it comes from

• Two commercial plans. A spouse's plan and the patient's own. The birthday rule or the employee-versus-dependent rule decides which is primary, and the patient often doesn't know.
• Medicare with a working-aged patient. An employer group plan of 20 or more employees is primary to Medicare. Medicare denies with 22 when its records show active employer coverage.
• An injury. Anything that could be a car accident or a work injury triggers a COB questionnaire. In an orthopedic practice, that's a large share of new patients. If the questionnaire goes unanswered, the claim sits.
• Stale records. The other coverage ended years ago and the payer's file was never updated. The patient has one plan, and it's denying anyway.

Is it recoverable?

Yes, in nearly every case, because the money was never denied on the merits. The risk is time. Each step (patient questionnaire, primary payer's determination, resubmission to the secondary) has its own clock, and a CO-22 that nobody works becomes a CO-29 timely-filing denial at the secondary a few months later.

The fix

1. Verify coverage with the patient, the same week. Which plans, which is primary, is there an accident or injury involved. Most payers accept the update by phone or portal.
2. If there is a primary, bill it, get its remittance, then bill the secondary with the primary's EOB attached. Florida gives you a statutory floor on fully insured plans: 90 days after the primary's determination to file with the secondary, regardless of the contract's usual window. The CO-29 note covers that exception.
3. If there is no other coverage, have the patient (or your office, on the patient's behalf) update the payer's COB file, then resubmit. Keep the confirmation number.
4. If it's an accident or work injury, route it properly: auto PIP or the workers' comp carrier is primary, and the commercial payer's denial was correct. Florida workers' comp has its own rules and rates.

The pattern to watch

CO-22 volume from one payer that isn't matched by real secondary coverage means that payer's COB file is stale for your patients, or its questionnaire is going to an address the patient doesn't check. Both are fixable in one call with a provider representative, and both stop a slow leak.