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CO-D5 Denial Code (Deactivated): Lab Component Codes

CO-D5 meant a lab claim was denied because it lacked the individual lab codes included in the test. X12 deactivated the code and directs payers to CARC 16 with remark codes, such as M126.

X12 deactivated CARCD5 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-D5 (CARC D5)
Status: Deactivated StoppedOctober 16, 2003 (in use since January 1, 1995).
Code set: Claim Adjustment Reason Codes (CARC)
Group codes: CO (Contractual Obligation): The lab needed to list the component tests; the denial was not a patient balance.
Official description: Claim/service denied. Claim lacks individual lab codes included in the test.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What CO-D5 meant

CARC D5 affected laboratory claims billed for a group of tests. The payer wanted to see which individual tests were included, and the claim did not list them. Without those component codes, the payer denied the line instead of guessing what was done.

What replaced it

The official note says to use code 16 and remark codes. Current remittances pair CO-16 with remark M126 for missing individual lab codes. The opposite problem, where individual tests were billed instead of the panel they form, is identified with remark N642.

If you still see CO-D5

It is only found in older lab remittances. When working a similar denial today, compare what the lab performed with the payer’s rules for panels and custom test groups. Add the component codes in the way the payer requires, whether as separate lines or in a narrative, and resubmit a corrected claim.

CO-16 (Claim/service lacks information or has submission/billing error(s).): Named replacement: claim lacks information, with a remark code.
M126 (Missing/incomplete/invalid individual lab codes included in the test.): Remark code for missing, incomplete, or invalid individual lab codes included in the test.
N642 (Adjusted when billed as individual tests instead of as a panel.): Remark code for tests billed individually that should have been billed as a panel.

CO-D5 FAQ

When does a payer need the individual tests?

When a lab bills a group of tests under a single code, some payers want the component tests listed so they can check what was performed and apply their pricing or coverage rules.

Is this the same as unbundling?

No. Here the payer wanted the components identified. Billing the components separately when a panel code applies is a different issue, flagged by remark N642.

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