Denial code · group CO
CO-22: Another plan appears to be primary; the payer wants that plan's payment before it pays
Short answer
CO-22 means the payer's records show another plan should pay first, so it will not adjudicate until it sees that plan's payment or a corrected coordination of benefits record. If the other coverage is real, bill it and then send this payer a secondary claim with the primary's adjudication. If it is old or wrong, the member has to update the record with the plan before you resubmit.
Look up other codes in the denial code library.
Last reviewed by the Remitwright billing team. Editorial policy
Group CO means contractual obligation: the balance is written off, not billed to the patient. The number is the reason; the two-letter group says who carries the balance.
Remark codes that usually come with CO-22
- MA04
- The secondary needs to know who the primary was and what it paid, and the claim did not show it
- N4
- The prior insurer's explanation of benefits is missing or incomplete
- MA92
- The claim leaves out the details of the member's other coverage
Common causes
The payer's file shows other coverage
An employer group plan, an auto or liability carrier, or a workers' compensation claim is recorded as primary for this member. Medicare runs a Medicare Secondary Payer program so that it does not pay first when a group health plan, workers' compensation, liability or no-fault insurer should. Commercial plans and Medicaid run similar checks.
Coverage that ended but was never closed
The member left a job or dropped a spouse's plan, nobody told the payer, and the payer's record still shows that plan as primary. Every claim denies CO-22 until the member updates the record.
Dependent children with two parents' plans
Both parents carry family coverage and the claim goes to the plan the family named at check-in. The plan applies its dependent coordination rule and decides the other parent's plan pays first.
A secondary claim without the primary's adjudication
The claim was meant for the secondary but went out without the primary's paid amount, adjustment codes and remittance date in the claim data, or without the EOB attached where the payer requires paper. MA04 or N4 names the gap.
An accident or injury diagnosis
A diagnosis that suggests an injury makes the payer ask whether auto, liability or workers' compensation coverage applies. Until the member or the office answers, the claim sits in CO-22.
How to fix it and resubmit
- 1
Read the eligibility response, not just the denial
Run a fresh 270/271 for the date of service and read the other-payer segments. The payer will often name the plan it believes is primary. Compare that to what the patient told you at intake.
- 2
Bill the real primary first
If the other coverage exists, send an original claim to that plan. When its 835 arrives, build the secondary claim with the primary's paid amount, adjustment codes and dates in the claim data, or the EOB attached for payers that want paper, and resubmit to the payer that denied CO-22.
- 3
Get the member to correct the record
When the other coverage is gone, the payer usually accepts a coordination of benefits update only from the member. Give the patient the payer's phone number and the exact information to update, then confirm with the payer before you resubmit. A termination letter from the old plan speeds this up.
- 4
Answer the accident question
For injury diagnoses, confirm with the patient whether a third party is involved and report it to the payer through its accident or subrogation questionnaire. If none is involved, the payer clears the hold and reprocesses; if one is, bill that carrier.
- 5
Protect the filing window
Document every call and the date the member updated coordination of benefits. If the resubmission arrives after the filing limit, that record supports a timely filing appeal.
How to prevent it
- Eligibility checks that read the other-payer segments of the 271 at every visit, not just active or inactive status
- A coordination of benefits question at check-in once a year and after any change of job, marriage or dependent status, recorded in the practice management system
- Secondary claims held until the primary 835 posts, then built from the primary's adjudication automatically
- Medicare patients asked the secondary payer questions at intake so group health, liability and workers' compensation coverage is found before the claim goes out
A CO-22 on a working Medicare beneficiary
An internal medicine practice bills Medicare for an office visit for a 67-year-old patient who is still working. Medicare denies CO-22 with MA04 because its records show the employer's group health plan as primary. At intake the patient had only shown his Medicare card. The biller confirms the employer plan on the 271, bills it as primary, waits for its 835, and then sends Medicare a secondary claim with the group plan's paid amount and adjustments. Medicare pays its secondary share. The practice adds the secondary payer questions to its intake for every Medicare patient. This is a hypothetical example.
Official text: the X12 claim adjustment reason code list. The meaning above is our paraphrase for billers; the list is the authority.
FAQ
Questions about CO-22
Is CO-22 a denial I can appeal?
The patient says there is no other insurance. What now?
What does Medicare mean by secondary payer?
Can I bill the patient while CO-22 is unresolved?
How long do I have to resubmit after a CO-22?
Next step
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While you wait: see the sample weekly report or read how to work claim denials. You can also download the sample weekly report (PDF).