Claim adjustment reason code
Denial code CO-B1 meaning
CARC B1, usually seen as CO-B1: The visits are not covered.
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- Reason code
- CARC B1
- Short name
- Non-covered visits
- Plain meaning
- The visits are not covered.
- Group codes
- CO-B1: Contractual obligation. The provider absorbs the amount under its contract or the payer's rules. Do not bill the patient for it. PR-B1: Patient responsibility. The patient, or a secondary payer, may owe the amount.
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 plan limits or excludes this type of visit.
What to check before resubmitting
- Check the plan's visit benefits.
Related reason codes
Related pages
Questions
What does denial code CO-B1 mean?
The visits are not covered. This is Rivvi's plain-English summary of CARC B1. X12's exact wording is on x12.org.
How do I fix CO-B1?
Check the plan's visit benefits.
Can I bill the patient for CO-B1?
When it comes with group code PR, the patient or a secondary payer may owe the amount. When it comes with CO, the provider writes it off.
Which group codes come with CARC B1?
Most often CO (contractual obligation) or PR (patient responsibility). 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.