Claim adjustment reason code
Denial code CO-45 meaning
CARC 45, usually seen as CO-45: The billed charge is higher than the fee schedule or contracted rate, and the difference is written off.
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- Reason code
- CARC 45
- Short name
- Charge over the allowed amount
- Plain meaning
- The billed charge is higher than the fee schedule or contracted rate, and the difference is written off.
- Group codes
- CO-45: Contractual obligation. The provider absorbs the amount under its contract or the payer's rules. Do not bill the patient for it. PR-45: 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
- Your charge is above the payer's allowed amount, which is normal for a contracted provider.
What to check before resubmitting
- With CO, write off the difference. Do not bill the patient for it.
- Check that the allowed amount matches your contract. If not, ask the payer to reprocess.
Related reason codes
Related pages
Questions
What does denial code CO-45 mean?
The billed charge is higher than the fee schedule or contracted rate, and the difference is written off. This is Rivvi's plain-English summary of CARC 45. X12's exact wording is on x12.org.
How do I fix CO-45?
With CO, write off the difference. Do not bill the patient for it. Check that the allowed amount matches your contract. If not, ask the payer to reprocess.
Can I bill the patient for CO-45?
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 45?
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.