CO-155: Patient Refused the Service/Procedure

What Does CO-155 Mean?

CO-155 is uncommon but may appear when a service was partially set up or prepared before the patient refused, and the payer denies the portion that was not completed. Under CO, the provider cannot bill the patient for the denied amount. The write-off covers the preparation costs that cannot be recovered.

CARC 155 appears on your remittance when the payer has denied the claim because the patient refused to receive the service or procedure that was billed. This is a fundamentally different type of denial — it is not about coverage, coding, or medical necessity. It is about whether the service was actually rendered.

The most common reason you see CARC 155 is a billing workflow breakdown: the service was scheduled and queued for billing, but the patient declined it before or during the encounter, and the claim was submitted anyway. This happens when clinical staff does not communicate the refusal to billing, or when automated billing systems generate claims for scheduled services without verifying they were completed. The second scenario is that the payer has information (from the patient or another source) indicating the patient refused the service, even though the provider's records show it was delivered.

This denial almost always appears with the OA group code, designating it as a general adjustment outside standard contractual or patient responsibility frameworks. If the patient genuinely refused the service, there is nothing to appeal — you cannot bill for a service that was not rendered. The correct action is to write off the claim and update the patient's records. If the service was actually performed despite the payer's assertion, you need to resubmit with clinical documentation proving the service was rendered, including treatment notes, patient signatures, and any consent forms.

How to Resolve

Confirm whether the service was rendered or refused, then either write off the claim or resubmit with proof the service was actually performed.

1. Review what was prepared vs. delivered Determine what portion of the service was completed before the patient refused and whether any completed component can be separately billed.
2. Write off the unrecoverable amount Write off the denied amount for the portion of the service that was not completed due to the patient's refusal.

How to Prevent CO-155

• Confirm patient consent and willingness to proceed before beginning service setup or preparation
• For expensive procedures, verify patient commitment at multiple checkpoints before incurring non-recoverable costs

Also Filed As

The same CARC 155 may appear with different Group Codes:

Related Denial Codes