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CO-D6 Denial Code (Deactivated): Medical Record Not Included

CO-D6 meant the claim was denied because it did not include the patient's medical record for the service. X12 deactivated it and directs payers to CARC 16 with remark codes, such as M127.

X12 deactivated CARCD6 on October 16, 2003. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Code: CO-D6 (CARC D6)
Status: Deactivated StoppedOctober 16, 2003 (in use since January 1, 1995).
Code set: Claim Adjustment Reason Codes (CARC)
Group codes: CO (Contractual Obligation): Supplying records was the provider's job, so the denial was not billed to the patient.
Official description: Claim/service denied. Claim did not include patient's medical record for the service.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What CO-D6 meant

CARC D6 was a documentation denial. The service billed was one the payer would not decide without seeing the patient’s medical record, and the record did not come with the claim. Rather than hold the claim, the payer denied it.

What replaced it

X12’s note says to use code 16 and remark codes. Today, a missing record typically appears as CO-16 with remark M127. Many payers also use CO-252, which says an attachment or other documentation is required to adjudicate the claim.

If you still see CO-D6

Old remittances are the likely source. To handle a missing-records denial now, identify exactly what the payer needs, often the visit note, operative report, or test results, and send it through the payer’s attachment channel with the claim number. Track which services trigger record requests so you can attach documentation up front on future claims.

CO-16 (Claim/service lacks information or has submission/billing error(s).): Named replacement: claim lacks information, explained by a remark code.
M127 (Missing patient medical record for this service.): Remark code for a missing patient medical record for this service.
CO-252 (An attachment/other documentation is required to adjudicate this claim/service.): An attachment or other documentation is required to adjudicate the claim.

CO-D6 FAQ

Why would a claim need the medical record attached?

Some services are reviewed before payment, such as unlisted procedures, unusual quantities, or services with coverage criteria. The payer needs the record to decide.

How do I send records for a claim now?

Use the payer's attachment process, such as an electronic attachment, portal upload, or fax with a cover sheet, and reference the claim number or attachment control number.

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