RARC N350: Missing Description for Unlisted or NOC Code

What Does RARC N350 Mean?

RARC N350 appears when a claim is submitted with a procedure code that by definition requires a supplemental description, and that description is missing. Unlisted procedure codes (those ending in 99 in CPT, such as 27299 or 64999) and Not Otherwise Classified (NOC) HCPCS codes are placeholder codes used when no specific code exists for the service performed. Because these codes are intentionally vague, payers require a written narrative describing exactly what was done.

Without this description, the payer has no way to determine what service was actually provided, whether it is covered, or how much to reimburse. Unlike specific CPT codes where the code itself defines the service, unlisted and NOC codes are essentially blank labels that the provider must fill in with details. The narrative is what the payer's medical reviewers use to make a coverage and pricing determination.

N350 is preventable if your billing workflow includes a checkpoint for unlisted codes. Whenever an unlisted or NOC code appears on a claim, the submission should be flagged to ensure a description — and typically supporting documentation like an operative report — is attached before the claim goes out.

What to Do

Prepare a detailed narrative description of the service performed. The description should include what the procedure or service was, the clinical indication, the technique or approach used, and the time spent if relevant. Many payers also want a comparison to the closest existing CPT or HCPCS code, along with an explanation of why that specific code does not accurately describe the service.

Attach the narrative along with any supporting clinical documentation (operative reports, clinical notes, photographs if applicable) and resubmit the claim. For electronic submissions, use the appropriate attachment method supported by the payer — this may be the PWK segment in the 837 transaction, a payer-specific portal upload, or a fax to the claims processing department with the claim number referenced.

Common Scenarios

• A surgeon bills CPT 27299 (unlisted procedure, pelvis or hip) for a novel surgical technique but submits the claim without any operative report or description attached
• A HCPCS NOC code is used for a specialty drug, but the claim does not include the drug name, dosage, NDC number, or route of administration
• A provider bills an unlisted evaluation code and assumes the diagnosis codes alone will suffice, but the payer requires a written explanation of the service
• An electronic claim for an unlisted procedure is submitted without the PWK attachment segment, and the payer has no way to retrieve the supporting description

Commonly Paired With

RARC N350 commonly appears alongside these CARC denial codes: