CO-251: Incomplete or Deficient Attachment/Documentation Received
CO-251 means your documentation is incomplete. Identify what is missing from the RARC codes, gather the complete records, and resubmit.
What Does CO-251 Mean?
When paired with Group Code CO, the incomplete documentation is the provider's responsibility to correct. The payer requires the complete information before processing the claim. The provider cannot transfer this cost to the patient.
CARC 251 means the payer received the correct type of document with your claim, but the document is incomplete, deficient, or unusable. Unlike CARC 250 (wrong document entirely), the issue with CARC 251 is that the right document was sent but it lacks necessary content.
Common deficiencies include missing pages from medical records, absent physician signatures, incomplete operative notes, illegible scanned documents, partial records that omit required sections, and documents missing mandatory dates or required fields. The payer cannot process the claim because the submitted documentation does not contain enough information to make a coverage or payment determination.
The accompanying RARC codes identify what specific information is still needed. Addressing the deficiency and resubmitting is typically faster than filing an appeal.
Common Causes
| Cause | Frequency |
|---|---|
| Submitted documentation is incomplete The correct type of document was submitted but it is missing pages, sections, or required information | Most Common |
| Medical records lack required clinical detail The medical records submitted do not contain sufficient clinical detail to support the claim (e.g., missing physician signature, incomplete operative notes) | Most Common |
| Attachment is illegible or poor quality The scanned or faxed document is unreadable due to poor image quality, making the information unusable | Common |
| Partial records submitted Only a portion of the requested medical records were included in the submission | Common |
| Required fields or signatures missing from documentation The document submitted lacks required signatures, dates, or mandatory fields needed for claim processing | Common |
How to Resolve
- Identify missing information from RARC codes Review the remark codes to determine what specific information the payer still needs.
- Obtain the complete documentation Locate the full version of the document with all required pages, signatures, and clinical details.
- Verify completeness and legibility Confirm all required elements are present and the document is scannable and readable.
- Resubmit the claim Send the claim with the complete, legible documentation.
- Request addendum if information was not documented If the required information was never documented, have the physician addend the medical record, then resubmit.
- Track resubmission Monitor the resubmitted claim to ensure it processes with the complete documentation.
The documentation submitted was incomplete or deficient. Locate and submit the complete documentation with all required information, then resubmit the claim. An appeal is not appropriate — provide the complete documentation.
Common RARC Pairings
The RARC code tells you exactly what triggered the CO-251:
| RARC | Description |
|---|---|
| MA130 | Your claim contains incomplete and/or invalid information, and no appeal rights are afforded. Submit the complete documentation and resubmit the claim → |
| N479 | Missing/incomplete/invalid information. Identify the specific deficiency and submit complete documentation → |
How to Prevent CO-251
- Review all attachments for completeness before submission — check for all pages, signatures, and required fields
- Use high-quality scanning settings to ensure legibility of faxed or scanned documents
- Implement a checklist for each attachment type to verify all required elements are present
- Train staff on documentation requirements for different claim types and payers
- Consider electronic health record integration for direct electronic attachment submission
- Perform a pre-submission quality review of all attachments
Also Filed As
The same CARC 251 may appear with different Group Codes:
Related Denial Codes
Sources
- https://x12.org/codes/claim-adjustment-reason-codes
- https://portal.ct.gov/-/media/ohs/health-it-advisory-council/apcd-advisory-group/data-submission-guide-workgroup/meeting-materials/6-30-22/carc-codes_final.pdf
- https://www.aapc.com/resources/claim-adjustment-reason-codes
- Codes maintained by X12. Visit x12.org for official definitions.