CO-159: Service Provided as Result of Terrorism

What Does CO-159 Mean?

CO-159 is the standard pairing for this code and represents a contractual denial. The payer is telling you that the service cannot be reimbursed under the commercial plan because it is classified as terrorism-related. Under CO, this amount is a provider write-off — you cannot bill the patient for it. The path forward is either to correct the coding (if the terrorism classification was an error) or to submit the claim to the appropriate federal program that covers terrorism-related medical expenses.

When CARC 159 appears on a remittance, the payer is telling you that the billed service or procedure was provided in connection with an act of terrorism and therefore falls outside the scope of the patient's commercial health plan coverage. The payer has determined — based on the claim data, diagnosis codes, or external cause codes — that the care was rendered as a direct result of a terrorism incident, and standard plan benefits do not apply.

This code is uncommon in everyday billing. It typically surfaces in the aftermath of a federally declared terrorism event when providers are treating patients injured in the incident. The denial is not necessarily a rejection of the medical necessity of the service — it is a coverage determination indicating that a different funding source (usually a federal program) should bear the cost. Programs such as FEMA disaster relief, the Public Readiness and Emergency Preparedness (PREP) Act, or state-level victim compensation funds may be the appropriate payer.

The most actionable scenario for billing staff involves a coding error: if a claim was inadvertently coded with ICD-10 external cause codes from the Y38 terrorism series when the service was actually unrelated to any terrorism event, the payer may automatically apply CARC 159. In this case, correcting the external cause codes and resubmitting with clear clinical documentation is the path to resolution. Note that some state Medicaid programs (e.g., Massachusetts) explicitly reject encounters submitted with CARC 159, so be aware of payer-specific handling rules.

Common Causes

How to Resolve

Determine whether the service was genuinely terrorism-related or miscoded, then either redirect the claim to the correct federal program or correct the coding and resubmit.

1. Audit the external cause codes Review the claim for any Y38-series ICD-10 codes or other terrorism-related identifiers. Determine whether they were applied correctly based on the clinical scenario.
2. Correct and resubmit if miscoded If the terrorism association was a coding error, correct the external cause codes and resubmit the claim with documentation supporting the accurate circumstances of the injury or illness.
3. Identify the correct federal program for genuine terrorism claims For services that were genuinely terrorism-related, research the applicable federal program (FEMA, PREP Act, state victim compensation) and submit the claim through the correct channel.
4. Appeal with documentation if resubmission fails If the payer still denies after correction, escalate to a formal appeal with comprehensive documentation proving the service was not related to terrorism.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-159:

How to Prevent CO-159

• Review all ICD-10 external cause codes on claims before submission to catch accidental terrorism-series codes
• Train coding staff on the Y38 terrorism series codes and when they should and should not be applied
• Ensure clinical documentation clearly states the cause and circumstances of every injury or illness
• Maintain awareness of federally declared terrorism events and route those claims to federal programs proactively

General Prevention

• Implement thorough patient intake screening to accurately document the circumstances of the injury or illness, distinguishing terrorism-related from non-terrorism-related events
• Train coding staff on proper use of ICD-10 external cause codes related to terrorism (Y38 series) to avoid incorrect associations
• Ensure clinical documentation clearly states the cause and circumstances of the injury or illness to prevent payer misclassification
• Review claims for terrorism-related codes before submission to catch accidental associations
• Maintain awareness of federally declared terrorism events in your service area and route those claims to the appropriate government programs proactively

Also Filed As

The same CARC 159 may appear with different Group Codes:

Related Denial Codes