Additional Documentation Required to Adjudicate Claim

What it means

The payer is saying they can't process this claim or service line as submitted because they need more supporting documentation. This code is almost always paired with a remark code that spells out exactly what's missing, so the real instructions live in that remark code.

Common causes

Claim was submitted without a required attachment (e.g., operative report, medical records, invoice, certificate of medical necessity)
Documentation was sent but didn't reach the payer or wasn't linked to the correct claim
Service requires prior authorization documentation that wasn't included
Unlisted or 'by report' procedure code billed without supporting notes
Coordination of benefits (COB) documentation (e.g., EOB from primary payer) was not attached
Specialty-specific documentation requirements (e.g., DME proof of delivery, implant invoices) not met

How to fix it

Check the accompanying remark code(s) on the remittance advice — they identify the specific document(s) needed
Pull the requested documentation (op notes, progress notes, invoices, prior auth letters, etc.) from the patient's chart
Confirm the payer's preferred submission method (fax, payer portal, mail) and any attachment control number requirements
Resubmit the claim or send documentation as a corrected claim or claim attachment per payer guidelines, not just as a standalone fax
Verify the documentation clearly matches the date of service and claim number to avoid mismatched records
Track the resubmission to confirm the payer received and processed the attachment within their timely filing window

Appeal / resubmit

Before appealing, confirm exactly what the paired remark code is asking for — appeals without the specific missing documentation are likely to be denied again. Include a cover letter referencing the original claim number, date of service, and the remark code, and attach the requested records directly rather than a general response. Keep a copy of the fax confirmation, portal submission receipt, or certified mail tracking as proof of timely response in case of a timely-filing dispute.

Frequently asked

Why did I get CARC 252 instead of a specific denial reason?

CARC 252 is a general 'documentation needed' code. It's always paired with a remark code (like an N-code) that tells you precisely what documentation is missing, so you need to look at both codes together.

Can I just resend the claim without the documentation?

No. Resubmitting without the requested attachment typically results in the same denial. The payer is waiting on specific records before they'll adjudicate the claim.

What if I already sent the documentation with the original claim?

Check whether it was submitted in a format the payer could process (some payers require electronic attachments via a portal or specific fax cover sheet) and confirm it was linked to the correct claim number.

Is there a deadline to send the missing documentation?

Yes, most payers apply their standard timely filing or appeal window to documentation requests, so send the materials as soon as possible and keep proof of submission.

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This content is for informational purposes only and does not constitute billing or legal advice. Always verify requirements with the specific payer and consult qualified billing or legal professionals as needed.