What does denial code CO-96 mean?

CO-96 means the charge is not covered and the contractual group code assigns the balance to the provider. The service was not a benefit under the plan, and your agreement makes that write-off yours rather than the patient's.

What is the difference between CO-96 and PR-96?

The reason is identical; the group code is not. CO-96 makes the non-covered balance a provider write-off, while PR-96 transfers it to the patient. Whether the payer applies CO or PR usually turns on whether a valid advance notice of non-coverage was obtained before the service.

Can an ABN turn a CO-96 into a billable balance?

A valid advance notice signed before the service can, because it is what establishes the patient accepted responsibility for a service they were told would not be covered. Ask the payer to reprocess with the signed notice attached; a notice obtained after the fact does not qualify.

CO-96: Non-covered charge the provider absorbs

CO-96 and PR-96 carry the same reason - the service is not a covered benefit - and differ in the only respect that changes what you do next: the group code. CO assigns the balance to the provider, PR assigns it to the patient. A biller who reads the number and ignores the letter will bill patients for balances that are contractually written off, which is the most consequential mistake this code invites. The group code is the payer's statement about liability, and it is not advisory.

What it means: The service is not covered, and the contractual group code assigns the resulting balance to the provider rather than to the patient.
Who pays the balance: Contractual - unlike PR-96, the group code here says you absorb it, and billing the patient without valid advance notice is a contract violation.
Group code CO: Contractual Obligation - the provider absorbs the balance and cannot bill the patient

Why CO-96 happens

The service is excluded from the plan and the provider's contract makes non-covered services a provider write-off absent valid advance notice.
A required advance notice of non-coverage was never obtained, so the payer applied the contractual group rather than the patient one.
The service is bundled into a covered benefit under the contract even though it is separately listed as non-covered.
A statutory exclusion applies that the provider agreement specifically bars from patient billing.
The remark codes identify a plan exclusion the contract treats as the provider's risk.

How to fix a CO-96 denial

1
Read the group code before anything else
CO and PR on the same reason number lead to opposite actions. Confirm which one posted before the balance moves anywhere, because the correction after a wrongly issued patient statement costs far more than the check.
2
Check whether a valid advance notice exists
If the patient signed a proper notice of non-coverage before the service and it meets the payer's requirements, ask the payer to reprocess with the patient-responsibility group code and attach the signed notice.
3
Confirm the service was genuinely non-covered
Read the remark codes against the plan documents. A service denied as non-covered that is in fact a benefit is an appeal, not a write-off, and the remark code is what distinguishes the two.
4
Write it off when the contract requires it
Where the agreement makes non-covered services the provider's responsibility and no valid notice was obtained, the balance is not collectible from the patient and holding it in A/R only distorts the aging.

Preventing CO-96 denials

Identify non-covered services before delivery and complete the payer's advance notice form, which is what moves the liability legitimately.
Train posting staff to key on the group code rather than the reason number when routing balances.
Audit patient statements for CO-group balances, since these are the write-offs most likely to reach a patient by mistake.

CO-96 frequently asked questions

What does denial code CO-96 mean?: CO-96 means the charge is not covered and the contractual group code assigns the balance to the provider. The service was not a benefit under the plan, and your agreement makes that write-off yours rather than the patient's.
What is the difference between CO-96 and PR-96?: The reason is identical; the group code is not. CO-96 makes the non-covered balance a provider write-off, while PR-96 transfers it to the patient. Whether the payer applies CO or PR usually turns on whether a valid advance notice of non-coverage was obtained before the service.
Can an ABN turn a CO-96 into a billable balance?: A valid advance notice signed before the service can, because it is what establishes the patient accepted responsibility for a service they were told would not be covered. Ask the payer to reprocess with the signed notice attached; a notice obtained after the fact does not qualify.

Related denial codes

PR-96 CO-50 PR-204 CO-55

Last reviewed August 5, 2026.

Denial code explanations are original plain-English summaries written for reference and are not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.