OA-189: Unlisted/NOC Code Used When Specific Code Exists

What Does OA-189 Mean?

OA-189 is uncommon and appears when the coding specificity issue requires further investigation or does not clearly fit under the provider's contractual obligation. This may occur when the payer acknowledges that the code selection is ambiguous and needs additional review.

CARC 189 appears on your remittance when the payer determines that a specific procedure code exists for the service you billed, but your claim used an unlisted or NOC code instead. Payers require the most specific code available because unlisted codes make it difficult to verify medical necessity, apply fee schedule rates, and process claims through automated adjudication systems.

The most common cause is coding staff defaulting to an unlisted code when they are unsure which specific code applies to the procedure. This happens frequently with new or uncommon procedures where the coder may not be aware that a specific code was added in a recent CPT or HCPCS update. Inadequate clinical documentation is the second most frequent trigger — when the operative report or procedure notes lack sufficient detail, coders cannot confidently select a specific code and fall back to the unlisted option.

Coding specificity matters because payers price unlisted codes differently (often requiring manual review and pricing), and the unlisted code pathway introduces delays and reduces the likelihood of full reimbursement. In most cases, CARC 189 is a straightforward fix — find the right code and resubmit. However, if the procedure genuinely has no specific CPT/HCPCS code, you will need to appeal with a detailed description of the procedure and a justification for why the unlisted code is appropriate.

How to Resolve

Search for the correct specific procedure code, verify it against the clinical documentation, and resubmit the claim with the specific code.

1. Contact the payer Request specifics on which code the payer believes should have been used, and whether they can provide guidance on the correct code for the procedure performed.
2. Resubmit with payer guidance Use the payer's recommended code and resubmit the claim. Document the payer's guidance for future reference.

How to Prevent OA-189

• When uncertain about code selection, contact the payer before submitting the claim to confirm the expected code
• Document payer preferences on code selection for ambiguous procedures

Also Filed As

The same CARC 189 may appear with different Group Codes:

Related Denial Codes