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N477 Remark Code: Dental Models Not Received

N477 means the payer needed dental models (study casts or an accepted digital equivalent) to review the service and did not receive them. The claim or line is usually held or denied until the models are submitted.

Quick facts

Code
N477 (RARC N477)
Status
Active In use since July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The service was denied or held because the required models were not on file. The office should supply them rather than bill the patient.
Official description
Missing Dental Models.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N477 means

Dental models are three-dimensional records of a patient’s teeth and bite, traditionally stone casts poured from impressions and increasingly digital scans. A dental consultant uses them to judge things a written narrative or a single X-ray cannot show well, such as crowding, occlusion, and how a planned prosthesis will fit.

When N477 appears on a remittance or dental EOB, the plan is saying the consultant needed those models and they were not part of the submission. It usually accompanies CARC 252 (attachment required) or CARC 16 (information missing). The service has not been judged on its merits yet; it simply could not be reviewed.

Common causes

  • The plan’s policy requires models for this type of treatment, but the office sent only the claim and radiographs.
  • The claim indicated attachments would follow, but the package was never mailed or uploaded.
  • Models were sent separately without the patient name, member ID, or claim number, so the plan could not match them.
  • Models were sent to the wrong address, portal, or department.

How to fix it

  1. Read the payer’s attachment instructions for the procedure. Note whether it wants physical casts, digital files, or either.
  2. Label everything clearly with the patient, subscriber ID, dates of service, and the claim or reference number from the remittance.
  3. Submit the models by the method the plan specifies, along with any narrative the consultant will need.
  4. If the claim was denied outright, send a corrected claim or reconsideration request as the plan directs, rather than a brand new duplicate claim.
  5. Track receipt. Ask the plan to confirm the models were logged against the claim before its attachment window closes.

How to prevent it

Keep a short list of which procedures each dental plan reviews with models, and flag those cases at treatment planning. Taking the impressions or scans at the records appointment is far easier than recalling a patient later. For general attachment workflows, see how CARC and RARC codes work together.

Codes that may appear with N477

  • CO-252 (An attachment/other documentation is required to adjudicate this claim/service.): An attachment is required to adjudicate the service; N477 identifies that attachment as dental models.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacked information needed for processing, and the missing piece is the set of models.
  • CO-163 (Attachment/other documentation referenced on the claim was not received.): The claim indicated models would follow, but the payer never received them.
  • N478 (Incomplete/invalid Dental Models.): Models were received but were incomplete or could not be used.
  • N481 (Missing Models.): The general version of this remark: missing models without the dental qualifier.
  • N40 (Missing radiology film(s)/image(s).): Missing radiographs or images, another common dental attachment request.
  • N37 (Missing/incomplete/invalid tooth number/letter.): Missing or invalid tooth number or letter on the claim itself.

N477 FAQ

Which dental services usually need models?

Payers most often ask for models when reviewing orthodontic treatment, major prosthetic work, or other cases where the bite and arch relationships matter. Requirements differ by plan, so check the plan's attachment guidelines.

Can I send digital scans instead of physical casts?

Some dental plans accept digital model images or scans through their attachment portal, while others still want physical models. Confirm the accepted format before sending anything.

Should I refile the whole claim?

Not always. Many payers let you send the models referencing the original claim number. If the claim was closed as denied, follow the payer's instructions for a corrected claim or reconsideration.