Claim adjustment reason code
Denial code CO-B20 meaning
CARC B20, usually seen as CO-B20: The service was partly or fully furnished by another provider.
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- Reason code
- CARC B20
- Short name
- Furnished by another provider
- Plain meaning
- The service was partly or fully furnished by another provider.
- Group codes
- CO-B20: 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
- Another provider already billed the service.
What to check before resubmitting
- Check who furnished the service.
Related reason codes
Related pages
Questions
What does denial code CO-B20 mean?
The service was partly or fully furnished by another provider. This is Rivvi's plain-English summary of CARC B20. X12's exact wording is on x12.org.
How do I fix CO-B20?
Check who furnished the service.
Can I bill the patient for CO-B20?
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 B20?
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.