Denial codes / CO-252
Denial code 252CO-252: Attachment required
An attachment or other documentation is required.
What to doFix and resend
Often recoverableYes, when worked
The letters in front matter. CO means the office can't bill the patient for the amount; PR means the patient may owe it. The same number can appear with either, so read both parts.
Why dental offices see it
- No x-ray, photo, perio chart or narrative was sent with a procedure that needs one (crowns, SRP, buildups, extractions, implants).
- The attachment was sent but not linked to the claim.
What to do
- Send the requested x-ray, photo, perio charting or narrative through the attachment service or portal.
- Reference the claim number and resubmit.
- Add an attachment rule for this insurer and procedure.
Stop it next time
Attach documentation up front for procedures that commonly need it. Each insurer's list differs; keep yours.
How many CO-252 claims are in your report? The free check counts them, ranks them by dollars and deadline and drafts the letter. It runs in your browser; nothing is uploaded.
Plain-English paraphrase; the official code list is maintained by X12. Insurer rules vary; check the insurer's provider manual. Not legal advice.