Claim adjustment reason code
Denial code CO-243 meaning
CARC 243, usually seen as CO-243: The network or primary care provider did not authorize the service.
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- Reason code
- CARC 243
- Short name
- Not authorized by the network or primary care provider
- Plain meaning
- The network or primary care provider did not authorize the service.
- Group codes
- CO-243: Contractual obligation. The provider absorbs the amount under its contract or the payer's rules. Do not bill the patient for it.
Plain-English summary written by Rivvi. X12 owns the CARC list and its exact wording, which is not reproduced here. Read it on the X12 CARC list (list dated November 1, 2025, checked October 23, 2026). This page does not decide how a claim is paid.
Common causes
- The patient's primary care provider did not refer or approve the service.
What to check before resubmitting
- Get the referral or authorization from the primary care provider.
Related reason codes
Related pages
Questions
What does denial code CO-243 mean?
The network or primary care provider did not authorize the service. This is Rivvi's plain-English summary of CARC 243. X12's exact wording is on x12.org.
How do I fix CO-243?
Get the referral or authorization from the primary care provider.
Can I bill the patient for CO-243?
With group code CO, no. CO means the provider absorbs the amount under its contract or the payer's rules.
Which group codes come with CARC 243?
Most often CO (contractual obligation). The group code, not the reason code, says who owes the amount.
What is the difference between a CARC and a RARC?
A claim adjustment reason code (CARC) says why a claim line was paid differently than billed. A remittance advice remark code (RARC) adds detail, such as which field is missing.