Group code
Indicates the category of financial responsibility, such as CO for contractual obligation or PR for patient responsibility.
Interactive reference
Medical billing denial code reference
Search common adjustment-code examples, then verify the complete remittance, related remark codes, payer policy, contract, claim, and documentation before taking action.
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8 matching codes.
CO-97Contractual obligation
What it means
Payment for the service is included in another service or procedure.
What to check next
Review the code pair, edit, modifiers, documentation, and payer policy. Do not add a modifier unless the record and current rules support separate reporting.
Educational reference only. Verify the full remittance, related remark codes, current payer instructions, contract, claim, and documentation. Do not enter patient information.
Read the whole message
A group code, CARC, and RARC answer different questions
CMS explains that line- or claim-level adjustments may use these code sets together. One code alone may not identify the correction or appeal path.
CARC
Explains why the payer adjusted the claim or service line. In CO-97, 97 is the Claim Adjustment Reason Code.
RARC
Adds detail to an adjustment or conveys remittance-processing information. Read every related remark code.
“CO-97” is convenient shorthand for a group code plus a CARC. Always use the combination actually reported. An adjustment is not automatically a billable patient balance, and not every adjustment represents a denied claim.
Crawlable reference
Common adjustment-code examples and review steps
These are plain-language summaries, not replacements for the current X12 descriptions or payer instructions.
CO-16
Contractual obligation · CARC 16Plain-language meaning
Claim or service lacks information needed for adjudication.
What to check next
Read the related remark code, identify the missing or invalid field or attachment, compare it with the source record, and follow the payer's correction or appeal process.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-18
Contractual obligation · CARC 18Plain-language meaning
Duplicate claim or service.
What to check next
Compare the claim number, dates, lines, frequency code, and prior remittance. Correct only if the submission is not a true duplicate and document the reason.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-22
Contractual obligation · CARC 22Plain-language meaning
Care may be covered by another payer under coordination of benefits.
What to check next
Confirm coverage order and coordination-of-benefits status for the date of service, then route or correct the claim using the payer's instructions.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-29
Contractual obligation · CARC 29Plain-language meaning
The payer says the filing time limit expired.
What to check next
Verify the applicable deadline and proof of original or corrected submission. Determine whether a documented payer or eligibility issue supports reconsideration or appeal.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-45
Contractual obligation · CARC 45Plain-language meaning
Charge exceeds the fee schedule or allowed amount.
What to check next
Reconcile the allowed amount, contractual adjustment, units, fee schedule, and contract terms before deciding whether the line is correct or needs review.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-50
Contractual obligation · CARC 50Plain-language meaning
The payer determined the service did not meet its medical-necessity criteria.
What to check next
Review the applicable policy, diagnosis, order, authorization, and documentation. Use the payer's reconsideration or appeal path when the record supports it.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-97
Contractual obligation · CARC 97Plain-language meaning
Payment for the service is included in another service or procedure.
What to check next
Review the code pair, edit, modifiers, documentation, and payer policy. Do not add a modifier unless the record and current rules support separate reporting.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-109
Contractual obligation · CARC 109Plain-language meaning
The claim was sent to a payer or contractor that says it is not responsible.
What to check next
Confirm the member's plan, payer ID, coverage order, claim type, and date-of-service responsibility before routing or correcting the claim.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-151
Contractual obligation · CARC 151Plain-language meaning
The payer says the information does not support the number or frequency of services.
What to check next
Review units, dates, frequency limits, documentation, authorization, and the applicable policy before correcting or appealing.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
CO-197
Contractual obligation · CARC 197Plain-language meaning
Required precertification, authorization, notification, or pretreatment was absent.
What to check next
Confirm whether authorization was required, obtained, matched to the service, and reported correctly. Check the payer's correction, reconsideration, or retro-authorization rules.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
PR-1
Patient responsibility · CARC 1Plain-language meaning
Deductible amount assigned as patient responsibility.
What to check next
Reconcile the remittance with benefits, contract terms, prior payments, and the patient ledger before moving the amount into the patient-balance workflow.
Group code shown: PR. Confirm the actual group code and every associated RARC on the remittance.
PR-2
Patient responsibility · CARC 2Plain-language meaning
Coinsurance amount assigned as patient responsibility.
What to check next
Reconcile the remittance with benefits, allowed amount, contract terms, and prior payments before moving the balance into patient responsibility.
Group code shown: PR. Confirm the actual group code and every associated RARC on the remittance.
PR-204
Patient responsibility · CARC 204Plain-language meaning
The payer says the service is not covered under the patient's current benefit plan.
What to check next
Confirm benefit coverage, exclusions, date-of-service eligibility, notices, authorization, and whether another payer or appeal path applies.
Group code shown: PR. Confirm the actual group code and every associated RARC on the remittance.
CO-167
Contractual obligation · CARC 167Plain-language meaning
The payer says the diagnosis is not covered.
What to check next
Review the payer policy and the diagnosis supported by the documentation. Correct only when the record and current coding rules support a different code.
Group code shown: CO. Confirm the actual group code and every associated RARC on the remittance.
Primary sources and review record
Last content review: August 6, 2026. X12 maintains the CARC and RARC lists; CMS explains how the group code, CARC, and RARC work together on Medicare remittance advice. Code lists and payer requirements can change, so verify the current source before acting.
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