Diagnosis does not match the patient's age
An ICD-10 code on the claim is defined for a different age group (newborn, pediatric, maternity, adult).
CO = Contractual Obligation. The provider owes the difference. The patient cannot be billed for this amount. The same reason code can appear with a different group code; the group decides who may be billed.
Usual causes
- Wrong diagnosis code picked from a lookup.
- Wrong date of birth on the claim.
The fix
Check the date of birth and the diagnosis. Correct whichever is wrong and send a corrected claim.
Appeal or corrected claim?
Corrected claim.
Deadline to watch
Timely filing limit.
Exact limits are in your payer contract or provider manual. When in doubt, send the correction or appeal this week.
CO-9 in short
What does CO-9 mean?
An ICD-10 code on the claim is defined for a different age group (newborn, pediatric, maternity, adult). The official X12 text reads: "The diagnosis is inconsistent with the patient's age. Usage: Refer to the 835 Healthcare Policy Identification Segment (loop 2110 Service Payment Information REF), if present."
What usually causes a CO-9 denial?
Wrong diagnosis code picked from a lookup. Wrong date of birth on the claim.
How do I fix CO-9?
Check the date of birth and the diagnosis. Correct whichever is wrong and send a corrected claim.
Should I appeal CO-9 or send a corrected claim?
Corrected claim. Corrected claim.
What deadline applies to CO-9?
Timely filing limit.