Claim adjustment reason code
Denial code CO-39 meaning
CARC 39, usually seen as CO-39: The payer denied the service when the authorization was requested.
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- Reason code
- CARC 39
- Short name
- Authorization was denied
- Plain meaning
- The payer denied the service when the authorization was requested.
- Group codes
- CO-39: 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 prior authorization request was reviewed and not approved.
What to check before resubmitting
- Read the authorization denial letter.
- Appeal the authorization decision with the documentation, or have the patient sign a waiver where allowed.
Remark codes that often come with it
Related reason codes
Related pages
Questions
What does denial code CO-39 mean?
The payer denied the service when the authorization was requested. This is Rivvi's plain-English summary of CARC 39. X12's exact wording is on x12.org.
How do I fix CO-39?
Read the authorization denial letter. Appeal the authorization decision with the documentation, or have the patient sign a waiver where allowed.
Can I bill the patient for CO-39?
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 39?
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.