CO 96 denial code

What CO-96 means

CO-96 means the payer classified the charge as non-covered: the item or service is outside the benefit package as billed. This is different from a medical necessity denial. The payer is not weighing clinical evidence; it is saying the charge falls into a category it does not pay for, or was billed in a way that lands it in one.

The CO group code means contractual obligation, so the denied amount is a provider write-off and the patient cannot be billed for it. Whether the group code is CO or PR (patient responsibility) is the entire financial question with code 96, and for Medicare it usually turns on liability notices: a beneficiary who signed a valid ABN before the service, with the claim billed using the proper liability modifier, can be held responsible, and the denial comes back PR instead of CO.

Like CO-16, reason code 96 is required to arrive with at least one remark code explaining the adjustment. The remark code is where the actionable information lives.

Common causes

• Statutory exclusions. Services Medicare never covers regardless of necessity. Remark code N425 flags this bucket.
• Category mismatches. The item does not meet the criteria for the code or benefit category under which it was billed (remark code N180); often fixable, because the real problem is coding, not coverage.
• Missing liability or attestation modifiers. Claims for likely-non-covered services billed without GA (ABN on file), GY (statutorily excluded), or GZ (no ABN obtained) leave the payer to assign liability by default.
• Benefit-specific exclusions on commercial plans: the service exists in some plans’ benefit sets but not this patient’s.
• Coverage that lives elsewhere: the charge is non-covered by this payer because another arrangement holds the benefit (compare CO-24).

How to fix and resubmit

1. Read the paired remark code. N425 (never covered) and N180 (doesn’t meet the billed category) lead to completely different next steps. Your MAC publishes resolution guidance by reason-plus-remark pairing.
2. If the claim was billed incorrectly (wrong code for what was actually provided or a required modifier omitted), correct it. For Medicare, Noridian’s guidance for these denials is to request a reopening for simple billing errors, such as an inadvertently omitted modifier.
3. If the denial turned on liability modifiers (KX, GA, GZ, GY) and you have supporting documentation, file a redetermination with the records attached. For Medicare Part B that request is due within 120 days of the remittance date.
4. If the service is genuinely excluded and no ABN was obtained, write it off. Do not bill the patient; without an advance notice, the CO group code stands and patient billing is improper.
5. If a valid ABN exists but the claim went out without the GA modifier, request a reopening to add it so liability shifts to the patient correctly.

How to prevent it

Know your exclusions before the visit: keep a list of the statutorily excluded and payer-excluded services your practice commonly provides, and verify benefits for anything questionable. Make ABNs routine for Medicare services with doubtful coverage, and pair them with the correct liability modifier at charge entry: an ABN that never reaches the claim is worthless. Check that items are billed under the right benefit category, since category-mismatch denials (N180) are self-inflicted. The denial codes index covers the neighboring coverage denials, especially CO-50.