CO-6 Denial Code: Procedure/Revenue Code Inconsistent With Patient Age

What does denial code CO-6 mean?

CO-6 means the procedure or revenue code you billed is inconsistent with the patient's age. The payer's front-end edits compare the date of birth on the claim against the age range built into the code, and the line failed that check. Nothing about benefits or medical necessity has been decided; the claim tripped a demographic logic edit.

Here is a real-world example. A pediatric practice bills 99392 (preventive visit, age 1 through 4) at $165.00 for a child whose registration record shows DOB 03/12/2015 instead of 03/12/2021. The ERA shows: billed $165.00, allowed $0.00, CO-6 $165.00, paid $0.00. The child is actually three; the typo made the payer think she was ten.

Why did the claim get a CO-6?

• Wrong date of birth keyed at registration or pulled from an outdated record. This is the number one cause, and the front desk usually never sees the fallout.
• Age-specific CPT selected incorrectly, such as an adult preventive code (99386) for a 17-year-old, or a pediatric critical care code for an adult.
• Vaccine product and admin code mismatch, like billing the pediatric formulation NDC for an adult patient.
• Payer age policy stricter than CPT. Some Medicaid programs age-restrict codes (fluoride varnish, EPSDT screens) beyond the CPT description, so a code that is technically valid still denies.

How do you fix and resubmit a CO-6 denial?

1. Verify the patient's DOB against the insurance card, the eligibility response, and your registration screen. If they disagree, that is your answer.
2. If the DOB was wrong, correct it in the system first, then resubmit. Fixing only the claim leaves the next visit to deny the same way.
3. If the DOB is right, the code is wrong. Select the age-appropriate CPT and rebill as a corrected claim.
4. If both look right, check the payer's own age policy; if you disagree with their edit, that is the one scenario worth appealing.

Use the denial code lookup to read any remark codes on the line; they often say whether the payer flagged the procedure code or the revenue code.

How do you prevent CO-6 denials?

Run real-time eligibility at every visit and reconcile the DOB in the 271 response against your registration record; a mismatch there predicts the denial before you ever bill. Add age-range edits for preventive, vaccine, and newborn codes to your claim scrubber, and template your age-banded preventive codes so the system picks the band from the DOB instead of trusting a human to. Practices that scrub demographics up front routinely keep this denial near zero and protect their clean-claim rate.

Can you appeal a CO-6 denial?

Usually there is nothing to appeal; you correct and resubmit. Appeal only when the DOB and the code are both correct and the payer's age edit is wrong or stricter than its published policy. In that case send a reconsideration citing the CPT code description and the payer's own medical policy, and generate the letter with the appeal letter generator. Check your window with the appeal deadline calculator; most commercial payers give 90 to 180 days.