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Attachments and requested documentation · Last verified 2026-08-30

CARC 252 denial code on dental claims

Independent publisher · Drafted with AI assistance, verified against primary sources · Credentialed review pending

CARC 252 is the “Attachment required” code on a dental remittance. Correct it and resubmit inside the filing window; this is not an appeal.

Group code: X12 restricts the group code on CARC 252 to CO or PI. In CAQH CORE business scenario 1 — additional information required — a 252 may carry only CO or PI, never PR, so the balance is not the patient's. The hedge that travels with it: a payer whose business requirements are not met by that scenario is not bound to the CORE combinations at all.

Registry entry: X12 Claim Adjustment Reason Code 252 — in the code set since 2012-09-30; description last revised 2013-06-02; active, with no deactivation date. Read on the list published 2025-11-01.

Remark code required:this code's own definition requires one, so a remittance carrying it without a remark code is incomplete.

Verdict

Technical — fix and resubmit

The route here is correcting the identified defect and resubmitting as a corrected claim, inside the timely-filing window, rather than arguing the decision.

Send what was asked for rather than arguing the decision. Work from the payer's own published documentation requirements for the procedure so the resubmission cannot be judged deficient a second time, and watch the response window — leaving the request unanswered turns a 252 into a 226.

The verdict cannot be settled from the CARC alone — the remark code that arrived with it carries the specific reason.

The appealability verdicts on these pages are Dentovio's editorial classification. No standards body or payer publishes an appealability taxonomy: X12 defines what a code means, not what to do about it. Each verdict is built from the code's own mechanics and the payer and federal documents cited on the page, and it is a starting point for triage rather than a prediction of any outcome.

What it means in dental

The payer cannot finish adjudicating without documentation it has not received, and must name what is missing in an accompanying remark code.

This is the attachment code, and the dental specifics live in the remark layer rather than in 252 itself. The perio-charting remark codes N401 and N402 replaced the older N483 and N484, which X12 stopped on 2015-05-01 — do not work from a guide that still cites them. Payers also differ on what must be attached versus retained: New York Medicaid requires radiographs to be submitted with prior-approval requests and for prefabricated crowns, but requires the periodontal detail behind scaling and root planing to be kept in the treatment record rather than sent with the claim.

What to do

  1. 1.Read the remark code: it names the document, and since 2026-07-01 the imaging remarks are specific down to bitewings and pre- and post-operative views
  2. 2.Match the resubmission against the payer's published documentation list for that procedure
  3. 3.Check whether the payer wants the record submitted or retained — for periodontal detail, some require only that you keep it

Remark codes verified with this CARC

X12 defines no CARC-to-RARC pairings. Each combination below is either a payer's own published crosswalk — true for that payer's internal reason code, not as a general rule — a CAQH CORE-required combination, or a remark whose registry meaning describes this adjustment.

N401 · Required combination under the CAQH CORE rule

Periodontal charting was not supplied.

What to do: Attach complete charting for the quadrants billed, with probing depths recorded.

A CORE-required combination for 252 in business scenario 1, under group code CO or PI (v3.10.0, February 2026).

N706 · Required combination under the CAQH CORE rule

Documentation the payer needs is missing.

What to do: Identify what the payer's policy for the procedure requires and send it; the remark itself does not name the document.

A CORE-required combination for 252 (v3.10.0, February 2026). It is not a listed partner for 226.

N928 · Matches on the remark's registry meaning — no source pairs them

A bitewing or periapical image is missing or unusable.

What to do: Send a dated, diagnostic-quality image of the type named, labelled with the patient and the date it was taken.

One of the dental imaging remark codes X12 started on 2026-07-01. No combination list pairs it with a CARC yet, so treat it as the remark that describes this adjustment rather than as a fixed pairing.

N931 · Matches on the remark's registry meaning — no source pairs them

Pre-operative or post-operative bitewing or periapical images are missing or unusable.

What to do: Send the pre-operative image the payer's criteria name; for most restorative reviews that is the diagnostic evidence the decision turns on.

Same 2026-07-01 imaging batch. Any guide written before that date does not have these codes.

Documentation pages for this denial family

The durable fix is submitting what the payer's published criteria ask for the first time:

Read with this code

Sources

Last verified 2026-08-30. Dentovio is an independent publisher — not a payer, the ADA, X12, CAQH CORE, or any government agency. Code meanings and remark-code meanings on this page are Dentovio's own wording, written from the official X12 Claim Adjustment Reason Code and Remittance Advice Remark Code lists and linked back to them; X12 holds the copyright in those lists and its descriptions are not reproduced here. CDT codes are referenced by number only; CDT is the American Dental Association's copyrighted code set and this page does not reproduce ADA descriptors. Appealability verdicts are Dentovio editorial classification, not a standard. Every fact traces to the code steward's registry, a federal rule or manual, a HIPAA operating rule, an association publication, or a named payer's own document — never to a billing blog. This page was drafted with AI assistance and verified against the primary sources linked here. It has not been reviewed by a credentialed dental billing specialist, attorney, or clinician. Educational billing reference only — not billing, legal, or clinical advice. Plan contracts control individual outcomes, and processing policies usually live in the payer's provider manual rather than in the signed agreement. How this data is verified