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CO-D12 Denial Code (Deactivated): Purchased Test Details

CO-D12 meant the claim did not identify who performed a purchased diagnostic test or the amount the billing provider was charged for it. X12 deactivated it and pointed to CARC 17, since retired; today it is typically CARC 16 with remark M133.

X12 deactivated CARCD12 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-D12 (CARC D12)
Status: Deactivated StoppedOctober 16, 2003 (in use since January 1, 1995).
Code set: Claim Adjustment Reason Codes (CARC)
Group codes: CO (Contractual Obligation): The billing provider had to report the purchased-test details; the patient was not billed.
Official description: Claim/service denied. Claim does not identify who performed the purchased diagnostic test or the amount you were charged for the test.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What CO-D12 meant

When a practice buys a diagnostic test from an outside supplier and bills for it, many payers pay no more than the practice’s cost. CARC D12 was the denial for claims that left out who performed the purchased test or how much the practice was charged, so the payer could not apply that limit.

What replaced it

X12’s note says to use code 17, which the CO-17 page covers, but that code has also been retired. Today these claims are typically denied with CO-16 plus remark M133, or N283 when the purchased service provider identifier is missing or invalid.

If you still see CO-D12

It is historical, but purchased-test rules still apply. For a current denial of this kind, get the supplier’s invoice and identifiers, mark the claim as including purchased services, and report the supplier and the net cost in the required fields before resubmitting.

CO-17Deactivated (Requested information was not provided or was insufficient/incomplete.): Named replacement at the time, itself later deactivated.
CO-16 (Claim/service lacks information or has submission/billing error(s).): Active code for missing information, paired with a remark code.
M133 (Claim did not identify who performed the purchased diagnostic test or the amount you were charged for the test.): Remark code: claim did not identify who performed the purchased test or the amount charged.
N283 (Missing/incomplete/invalid purchased service provider identifier.): Remark code for a missing or invalid purchased service provider identifier.

CO-D12 FAQ

What is a purchased diagnostic test?

A test performed by an outside supplier that the billing provider buys and then bills the payer for. Payers often limit payment to what the billing provider paid, so they need the performer and the cost.

What claim fields are involved?

Claim formats include an indicator for purchased services, the purchased service provider, and the amount charged. The payer's companion guide explains which are required.

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