CO 116 denial code

Claim adjustment reason code 116. Often reported as CO 116.

Advance notice did not meet requirements

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 116 means

The payer did not accept the patient's signed liability notice because it was not completed as required.

Providers use advance notices to tell patients a service may not be covered, so the patient can agree to pay. This code means the notice on file did not meet the payer's requirements, so the payer will not let the provider shift the cost to the patient on that basis.

Common problems are missing information, a generic notice, or timing after the service started. The group code usually points to provider liability.

Group codes seen with 116

On a remittance, 116 comes after a group code. These are the ones it is most often reported with:

• CO 116 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• The notice did not name the specific service and reason for expected non-payment.
• The patient signed the notice after the service was provided.
• The notice used an outdated or unapproved form.
• The notice was given routinely to every patient instead of for a specific reason.

What to do next

1. Review the signed notice against the payer's form and content requirements.
2. Appeal with the notice if it was valid and correctly completed.
3. Train front desk and clinical staff on when and how to issue liability notices.

Related codes

• 96 (reason code) Service not covered by the plan
• 50 (reason code) Not medically necessary per the payer
• 204 (reason code) Not covered under the patient's plan