Claim adjustment reason code
Denial code CO-151 meaning
CARC 151, usually seen as CO-151: The payer decided the information sent does not support this many services or this frequency.
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- Reason code
- CARC 151
- Short name
- Number or frequency of services not supported
- Plain meaning
- The payer decided the information sent does not support this many services or this frequency.
- Group codes
- CO-151: 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
- Units or visits exceed the payer's frequency limit or MUE.
- Repeat services were billed without a reason.
What to check before resubmitting
- Check the CMS medically unlikely edit (MUE) for the code.
- Appeal with documentation, or rebill the supported units.
Remark codes that often come with it
Related reason codes
Related pages
Questions
What does denial code CO-151 mean?
The payer decided the information sent does not support this many services or this frequency. This is Rivvi's plain-English summary of CARC 151. X12's exact wording is on x12.org.
How do I fix CO-151?
Check the CMS medically unlikely edit (MUE) for the code. Appeal with documentation, or rebill the supported units.
Can I bill the patient for CO-151?
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 151?
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.