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CO-38 Denial Code (Deactivated): Not by Network/PCP

CO-38 meant the services were not provided by, or not authorized by, the network or primary care providers the plan required. X12 deactivated it and names CARC 242 and CARC 243 as its replacements.

X12 deactivated CARC38 on January 1, 2013. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Quick facts

Code
CO-38 (CARC 38)
Status
Deactivated StoppedJanuary 1, 2013 (in use since January 1, 1995).
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider absorbed the amount, typically because the network or PCP rules were part of its agreement with the plan.
  • PR (Patient Responsibility): Some plans assigned the cost to the member for going outside the designated network without approval.
Official description
Services not provided or authorized by designated (network/primary care) providers.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-38 meant

CARC 38 was used by managed care plans, such as HMOs, that route members through a designated primary care provider or a closed network. It meant one of two things: the care came from a provider outside that designated group, or the care was delivered without the approval the PCP or network was supposed to give. The single code blurred those two very different fixes.

What replaced it

X12’s notes name two replacement codes, one for each half of the old meaning:

  • CO-242: services not provided by network or primary care providers.
  • CO-243: services not authorized by network or primary care providers.

Related active codes include CO-288 for a missing referral and CO-279 when the plan limits members to preferred network providers.

If you still see CO-38

It was retired more than a decade ago, so current ERAs should use 242 or 243. If one arrives with 38, ask the payer to identify which condition applied.

On the claim, check the patient’s plan type and assigned PCP for the date of service, confirm your participation status, and look for a referral or authorization on file. If you have one, send it with a reconsideration request. If you were out of network and the plan allows it, the member’s out-of-network benefits may apply.

  • CO-242 (Services not provided by network/primary care providers.): Named replacement: services not provided by network or primary care providers.
  • CO-243 (Services not authorized by network/primary care providers.): Named replacement: services not authorized by network or primary care providers.
  • CO-288 (Referral absent): Referral absent, a common cause of the same kind of denial.
  • CO-279 (Services not provided by Preferred network providers.): Services not provided by preferred network providers, for member network limitations.

CO-38 FAQ

Which replacement code applies to my situation?

If the problem is who performed the service, it is CARC 242. If the service was performed by an acceptable provider but lacked the PCP or network approval, it is CARC 243.

Can I appeal an old CO-38?

Only within the payer's appeal window. If you have a referral or authorization dated before the service, include it. After the window closes, the claim is usually written off.