Claim adjustment reason code
Denial code CO-109 meaning
CARC 109, usually seen as CO-109: This payer or contractor does not cover the claim. It should go to another payer or contractor.
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- Reason code
- CARC 109
- Short name
- Wrong payer
- Plain meaning
- This payer or contractor does not cover the claim. It should go to another payer or contractor.
- Group codes
- CO-109: 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 is in a Medicare Advantage plan, not Original Medicare.
- The claim went to the wrong Medicare contractor, such as a DME claim sent to a Part B contractor.
- The patient's coverage changed.
What to check before resubmitting
- Run an eligibility check for the date of service.
- Send the claim to the payer or contractor shown.
Related reason codes
Related pages
Questions
What does denial code CO-109 mean?
This payer or contractor does not cover the claim. It should go to another payer or contractor. This is Rivvi's plain-English summary of CARC 109. X12's exact wording is on x12.org.
How do I fix CO-109?
Run an eligibility check for the date of service. Send the claim to the payer or contractor shown.
Can I bill the patient for CO-109?
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 109?
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.