What is CO 6 Mean?
Claim Adjustment Code (CARC) 6, also known as CO 6, means that the procedure or revenue code billed does not match the patient’s age.
In simple terms, the insurance payer has determined that the service billed is not appropriate for the patient’s age group based on medical coding and payer policy guidelines.
For example, a CPT code for a pediatric vaccination cannot be billed for an adult patient, and vice versa.
Common Reasons for CO 6 Denials
Below are some Common reasons for CO 6 denial.
1. Age Mismatch with Procedure/Revenue Code
Certain CPT or HCPCS codes are designed for specific age groups — for example, pediatric, adolescent, adult, or geriatric patients.
If a code meant for one age range is billed for a patient outside that range, the payer system automatically flags and denies the claim.
Example: Billing a pediatric vaccination code for a 30-year-old patient.
2. Incorrect Date of Birth (DOB)
Sometimes the issue lies not with the code, but with the patient’s demographic data. A simple data entry error during registration or claim creation can make the patient appear older or younger than they really are — resulting in an age conflict.
Example: Entering 2012 instead of 2002 as the birth year.
3. Coding Error
Coders may inadvertently select the wrong CPT or revenue code that doesn’t align with the patient’s age bracket. This is especially common when multiple codes exist for the same service but with different age restrictions.
Example: Choosing CPT 99386 (ages 40-64) instead of 99385 (ages 18-39).
4. Missing or Insufficient Documentation
If the claim lacks supporting documentation explaining why an age-restricted service was performed, the payer may deny it.
Example: A child receiving a diagnostic test typically done for adults without clinical justification in the notes.
5. Payer-Specific Policy Restrictions
Every payer has its own coverage rules and edits related to patient age.
Some insurers apply stricter age validation rules for preventive exams, screenings, and immunizations. Even if the code is technically valid, the payer may deny it based on internal policy criteria.
Example: A screening procedure allowed only for patients 50+ years being billed for a 45-year-old.
On-Call Scenario: CO 6 – Procedure or revenue code billed does not match the patient’s age
Call Flow
Start the Call – Gather Denial Information
“Hello, I’m calling regarding a denied claim. Could you please confirm the denial date for this claim?”
Verify Claim History
“Check if payment was received previously for the same CPT code under the same insurance?”
If YES (Same CPT Paid Previously)
“Since we’ve received payment for the same CPT code earlier, could you please reprocess the claim?”
“What is the turnaround time (TAT) for reprocessing?”
“May I have the claim number and call reference number for my records?”
If NO (No Previous Payment for Same CPT)
“What is the time limit to submit a corrected claim for this denial?”
- If the claim is still within the time limit:
“Thank you. Could you please confirm the fax number or mailing address where we can send the corrected claim?”
- If the time limit has expired:
“In that case, may I know the appeal address or fax number to send an appeal?”
“Also, how much time do we have to file the appeal?”
“Finally, may I have the claim number and call reference number for documentation?”
Important Notes & Actions
1. Assign the Denial to the Coding Team
When this denial occurs, the first step is to assign it to the coding team for review.
Their responsibility is to:
Verify whether the billed CPT code matches the patient’s age criteria.
Provide the correct CPT code if an incorrect one was used.
Sometimes, the insurance representative may mention the age range applicable to the billed CPT during the call. Always document that information in your notes before forwarding the claim to the coding team — it helps coders make quicker, more accurate corrections.
2. Submitting the Corrected Claim
Once the coding team provides the correct CPT:
Update the claim with the corrected CPT code.
Submit the corrected claim to the insurance company, provided the timely filing limit for corrected claims has not been exceeded.
If the client instructs to proceed even after the time limit is crossed, follow their internal policy accordingly and note the decision for compliance records.
3. When the CPT Code Is Already Correct
If the coding team confirms that the original CPT code is correct, then the next step is to send an appeal to the insurance payer.
Before sending the appeal:
Check the appeal filing limit, which is calculated from the denial date (not the original submission date).
If the time limit has not expired, proceed with the appeal.
If the appeal time limit is already crossed, write off the claim unless the client requests that an appeal still be submitted.
Click here for more AR Scenarios and Denials.
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