Denial Code CO-6
Home > All Codes > CO Denial Codes > CO-6 Denial Code
Procedure code is inconsistent with the patient's age
The CO-6 denial code indicates that the procedure or service reported on the claim does not meet the payer's age-related requirements for the patient. This can occur when the patient's demographic information is incorrect or when the billed procedure has age-specific coverage or coding requirements.
Providers should verify the patient's date of birth, procedure code, medical documentation, and applicable payer policy before correcting or appealing the claim.
About CO-6
Denial Code
Group Code
Category
Quick Facts
CO (Contractual Obligation)
CO-6 is a Claim Adjustment Reason Code (CARC) used when a procedure or revenue code conflicts with the patient's age. Resolving the adjustment requires determining whether the issue involves patient demographics, procedure coding, or an age-specific coverage requirement.
CO-6
Patient Responsibility
Common Payers
Next Step
Generally No
Medicare, Medicaid, Commercial
Verify Patient Age
Patient Age
What Does CO-6 Mean?
The CO-6 denial code means the payer determined that the procedure or revenue code reported on the claim is inconsistent with the patient's age. CMS identifies CARC 6 specifically as an age-related procedure/revenue-code inconsistency.
Some healthcare services have age requirements established through coverage policies, coding guidelines, preventive-service criteria, or payer-specific rules. A claim can therefore receive CO-6 even when the procedure code itself is valid.
The denial may result from incorrect demographic information, an incorrect procedure code, or a legitimate age restriction. Identifying which issue applies is important before changing the claim.
Common Causes
CO-6 may occur when:
The patient's date of birth is incorrect.
The payer has different demographic information on file.
An incorrect CPT or HCPCS code was submitted.
An age-specific procedure code was used for the wrong age group.
A preventive or screening service has age restrictions.
The patient falls outside the payer's covered age range.
A pediatric service is reported for an adult patient.
The procedure code does not match the patient's documented age.
Identifying whether the problem involves demographics, coding, or coverage is important before making changes to the claim.
How To Fix CO-6
When CO-6 appears on a claim:
Review the EOB or ERA.
Verify the patient's date of birth.
Compare the claim with the payer's eligibility records.
Confirm the procedure or revenue code.
Review the patient's age on the date of service.
Check the medical record for the service performed.
Review age-specific coverage requirements.
Correct demographic or coding errors when identified.
Submit a corrected claim when appropriate.
Appeal when the original claim is accurate and coverage requirements were met.
Do not change the patient's demographic information or procedure code simply to obtain payment. Any correction must accurately reflect the patient and the service provided.
Documentation to Review
Before correcting or appealing CO-6, review:
Patient date of birth.
Eligibility information.
Original claim.
Procedure or revenue code.
Medical record.
EOB or ERA.
Payer coverage requirements.
Age requirements for the service.
These records help determine whether CO-6 resulted from incorrect claim information or a legitimate age-related coverage restriction.
Billing and Claim Considerations
CO-6 requires providers to determine why the age conflict occurred. Correcting the wrong part of the claim can lead to another denial or inaccurate billing.
If the date of birth was entered incorrectly, the demographic information should be corrected and the claim handled according to the payer's corrected-claim procedures. Providers may also need to ensure the payer's eligibility record contains the correct information.
When the patient's age is accurate, review the procedure or revenue code. Some services have age-specific coding or coverage criteria, so a valid code may still be inappropriate for that particular patient or payer policy.
The remittance advice should also be reviewed for additional remark codes. These may provide more specific information about the age restriction or coverage rule that resulted in the adjustment.
CPT/HCPCS Codes to Review
CO-6 is not tied to one specific procedure code, but some services have clear age-related coverage requirements. Relevant examples include:
G0105 — Colorectal Cancer Screening; High-Risk Individual
Review the patient's age and applicable screening eligibility requirements when an age-related adjustment occurs.
71271 — Low-Dose CT for Lung Cancer Screening
Verify that the patient meets the applicable age and other coverage requirements for lung cancer screening.
81528 — Colorectal Cancer Screening Test
Review the patient's age and applicable screening coverage requirements when CO-6 is reported.
These codes do not automatically result in CO-6. They are examples of services where patient age can be relevant to coverage and claim processing.
Modifiers to Review
Modifiers are not a routine fix for CO-6. However, certain Medicare age-related coverage situations can involve liability modifiers that affect how a noncovered service is processed.
Modifier GA — Waiver of Liability Statement Issued
Review when a valid Advance Beneficiary Notice was issued before a Medicare service expected to be denied as not reasonable and necessary.
Modifier GZ — Service Expected to Be Denied
Review when a Medicare service is expected to be denied and no valid Advance Beneficiary Notice is on file.
These modifiers should only be used when their specific requirements are satisfied. They do not make an otherwise age-ineligible service covered.
Common Billing Mistakes
Common mistakes involving CO-6 include:
Entering the patient's date of birth incorrectly.
Failing to compare claim demographics with payer records.
Selecting the wrong age-specific procedure code.
Ignoring age requirements for screening services.
Assuming every CO-6 adjustment is caused by incorrect demographics.
Changing a procedure code without reviewing the documentation.
Adding a modifier solely to bypass the denial.
Resubmitting the unchanged claim.
Appealing without first reviewing the applicable coverage requirements.
Verifying demographics and age requirements before resubmission can prevent repeated CO-6 adjustments.
When Should CO-6 Be Appealed?
A corrected claim is generally appropriate when CO-6 resulted from incorrect demographic or coding information.
An appeal or payer review may be appropriate when:
The patient's date of birth was correct.
The billed procedure accurately represents the service performed.
The patient met the applicable age requirements.
Documentation supports the billed service.
The payer applied the wrong age-related policy.
A payer processing error caused the adjustment.
Before appealing, verify both the patient's age on the date of service and the coverage requirements that applied to the procedure.
Frequently Asked Questions
Does CO-6 always mean the patient's date of birth is incorrect?
No. The patient's date of birth may be correct while the procedure or revenue code conflicts with an age-specific coding or coverage requirement.
Should the procedure code automatically be changed after receiving CO-6?
No. Review the medical record and coding requirements first. The procedure code should only be changed when the original coding was incorrect.
Can screening services receive CO-6?
Yes. Some preventive and screening services have age-related eligibility requirements that can result in an age-related claim adjustment.
Can a corrected claim resolve CO-6?
Yes. A corrected claim may resolve CO-6 when incorrect demographic or coding information caused the adjustment.
What should providers verify before appealing CO-6?
Verify the patient's date of birth, age on the date of service, billed procedure, medical documentation, eligibility, and applicable payer coverage requirements.
Related Denial Codes
CO-7 Denial Code
Procedure or revenue code conflicts with the patient's gender.
CO-8 Denial Code
Procedure code conflicts with the provider type or specialty.
CO-9 Denial Code
Diagnosis conflicts with the patient's age.
CO-10 Denial Code
Diagnosis conflicts with the patient's gender.
Need More Help?
Medical billing denial codes, insurance prefixes, and claim guidance in one searchable resource hub.
© 2026. All rights reserved.
Quick Links
Resources
About DenialCodeLookup
Terms and Conditions
Privacy Policy
