Denial Code Decoder
CO-167 — Diagnosis not covered
The diagnosis on the claim is not one the payer covers for this service. As with medical necessity, the care may be fine and the coding wrong — the documented condition may simply have been reported with a code outside the payer's covered list.
Billable to the patient? Generally not without a valid advance notice of non-coverage — review liability before moving any balance.
Where this denial is born
- Front desk
- Coding
- Claim build
- Submission
- Adjudication
This denial is usually created at the highlighted stage — that is where prevention lives.
Answer the questions — follow the path
The same questions an experienced biller asks, in order. Your answers draw the route to the right action.
Does the documentation support a covered, more specific diagnosis?
The full decision tree
Does the documentation support a covered, more specific diagnosis?
- Yes →
Correct the diagnosis and resubmit. Report the documented condition at its most specific covered code — never code FOR coverage, code what the record supports — and resubmit as a replacement.
- No →
Do you believe the policy is being misapplied?
Compare the denial against the payer's published coverage policy for the service.
- Yes →
Appeal citing the coverage policy. Quote the payer's own policy language and attach the clinical record showing the covered indication.
- No →
Resolve liability. With a valid advance notice the balance may go to the patient; without one, write off and add the service to the pre-service policy-check list.
- Yes →
Prevention
For services with narrow covered-diagnosis lists, verify the documented diagnosis against the payer policy before the claim goes out.
Related reading
The code list, and when it was last checked
X12 maintains the Claim Adjustment Reason Codes list, where this code is listed as 167. The list carries the number alone: the CO in front of it is the adjustment group the payer chose for this line, which decides who owes the balance, and the same code can arrive under a different group from a different payer. It has been on the list since June 30, 2005, and X12 last revised its entry on July 1, 2017.
Checked against the list revision dated November 1, 2025 on August 7, 2026, where it reads as an active code.
Sources
The paragraphs behind the guidance above. A page that tells you what to do about money should show you what the instruction rests on.
Drowning in CO-167 denials?
Our denial team works them for you — root cause to recovery.
Ready to improve your revenue cycle?
Tell us about your practice and we’ll tell you where we would start.