Official X12 description
“The diagnosis is inconsistent with the procedure.”
Source: X12 Claim Adjustment Reason Codes. The X12 External Code Lists are the single authoritative source for every CARC descriptor — always verify against the current release before building a claim-scrub rule.
What CARC 11 actually means
CARC 11 means the payer's medical-necessity edit does not connect the ICD-10 diagnosis you submitted to the CPT/HCPCS procedure you billed. Either the diagnosis does not appear on the payer's covered diagnosis list for this procedure (a Local Coverage Determination or Medical Policy), the diagnosis was truncated or coded at the wrong specificity, or the diagnosis linkage on the 837 was wrong. This usually clears with a corrected claim once the right diagnosis is linked; a true appeal is only warranted when the clinical record supports a covered diagnosis that was not originally coded.
Common root causes
- Diagnosis not on the payer's LCD / commercial coverage policy for the procedure.
- ICD-10 coded at insufficient specificity (e.g., an unspecified code where the payer requires a specific laterality or acuity).
- Diagnosis pointer on the 837P line pointed to the wrong ICD from the claim header.
- Documentation supports a different, covered diagnosis that was not captured at coding.
Prevention checklist
- Front-end medical-necessity scrubbing against LCDs and published commercial policies at charge entry.
- Specialty-specific ICD-10 specificity training; audit unspecified code usage monthly.
- Bidirectional sync with the EHR so the ordering diagnosis reliably follows the charge.
- Maintain a payer-by-payer covered-diagnosis matrix for high-volume procedures.
Appeal strategy — step by step
Most CARC 11 denials clear faster with the right remediation than with a formal appeal. Work the steps in order and escalate only when a lower-effort path has been ruled out.
- 1If a correctly coded, covered diagnosis exists in the chart but was not on the original claim, submit a corrected claim rather than an appeal.
- 2If the originally billed diagnosis is supported by the record and the payer's policy excludes it, appeal with the clinical note, a citation to the relevant LCD or medical-policy section, and any peer-reviewed literature supporting the clinical indication.
- 3For Medicare LCD denials, verify the Article A-code and Group 1 ICD list for the date of service (LCDs are retroactive to DOS, not billing date).
Sample appeal-letter language for CARC 11
Edit the bracketed fields before sending. This template is a starting point; a payer-specific appeal form may still be required — check the provider portal first.
Payer-specific notes
Payer-specific behavior for CARC 11 publishes here as the QuickIntell anonymized denial ETL ingests sufficient volume. In the meantime, consult the payer directory for the relevant provider manual and appeal form.
How common is CARC 11?
Out of 306 seeded CARCs, ranked by combined US monthly search volume for "CARC 11", "CO-11 denial", and "denial code 11".
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM prevents CARC 11
QuickRCM catches the root causes above before the 837 leaves the clearinghouse:
- Claim-scrub rules fire on every root cause listed above — the scrub references the same X12 CAS segment logic that drives the denial, so what the payer checks, QuickRCM checks first.
- When a denial lands, QuickRCM routes it to the correct worker with the documentation bundle already attached (op note, LCD citation, modifier rationale, EOB, primary 835).
- Appeal templates tuned to each CARC (including this one) pull the supporting facts from the claim and fill the bracketed fields automatically.
CAQH CORE code combinations for CARC 11
Under the CAQH CORE Payment and Remittance Uniform Use rule, health plans may pair CARC 11 only with the remark codes and group codes below for the defined business scenario 3 (Billed service not covered by the health plan). A combination outside this list on an 835 is itself a payer compliance issue worth raising.
| RARC | Remark description | Group code | Scenario |
|---|---|---|---|
| (no RARC) | CARC used without a remark code | CO, PI or PR | 3 |
| M25 | The information furnished does not substantiate the need for this level of service. If you believe the service should have been fully covered as billed, or if you did not know and could not reasonably have been expected to know that we would not pay for this level of service, or if you notified the patient in writing in advance that we would not pay for this level of service and he/she agreed in writing to pay, ask us to review your claim within 120 days of the date of this notice. If you do not request an appeal, we will, upon application from the patient, reimburse him/her for the amount you have collected from him/her in excess of any deductible and coinsurance amounts. We will recover the reimbursement from you as an overpayment. | CO, PI or PR | 3 |
| M51 | Missing/ incomplete/ invalid procedure code(s). | CO, PI or PR | 3 |
| M64 | Missing/ incomplete/ invalid other diagnosis. | CO, PI or PR | 3 |
| M76 | Missing/incomplete/invalid diagnosis or condition. | CO, PI or PR | 3 |
| MA63 | Missing/incomplete/invalid principal diagnosis. | CO, PI or PR | 3 |
| MA130 | Your claim contains incomplete and/or invalid information, and no appeal rights are afforded because the claim is unprocessable. Please submit a new claim with the complete/correct information. | CO, PI or PR | 3 |
| N115 | This decision was based on a Local Coverage Determination (LCD). An LCD provides a guide to assist in determining whether a particular item or service is covered. A copy of this policy is available at www.cms.gov/mcd, or if you do not have web access, you may contact the contractor to request a copy of the LCD. | CO, PI or PR | 3 |
| N386 | This decision was based on a National Coverage Determination (NCD). An NCD provides a coverage determination as to whether a particular item or service is covered. A copy of this policy is available at www.cms.gov/mcd/search.asp. If you do not have web access, you may contact the contractor to request a copy of the NCD. | CO, PI or PR | 3 |
| N657 | This should be billed with the appropriate code for these services. | CO, PI or PR | 3 |
Frequently asked questions — CARC 11
What does CARC 11 mean?
CARC 11 is an X12 Claim Adjustment Reason Code. The official definition is: "The diagnosis is inconsistent with the procedure." In plain English, the payer is telling you cARC 11 means the payer's medical-necessity edit does not connect the ICD-10 diagnosis you submitted to the CPT/HCPCS procedure you billed. Either the diagnosis does not appear on the payer's covered diagnosis list for this procedure (a Local Coverage Determination or Medical Policy), the diagnosis was truncated or coded at the wrong specificity, or the diagnosis linkage on the 837 was wrong. This usually clears with a corrected claim once the right diagnosis is linked; a true appeal is only warranted when the clinical record supports a covered diagnosis that was not originally coded.
How do I resolve a CARC 11 (CO-11) denial?
Start with the most common root cause: Diagnosis not on the payer's LCD / commercial coverage policy for the procedure. First step: If a correctly coded, covered diagnosis exists in the chart but was not on the original claim, submit a corrected claim rather than an appeal. See the full remediation and appeal checklist on this page before filing a formal appeal.
Is CARC 11 patient responsibility?
No — CARC 11 is typically carried under CO (Contractual Obligation) or OA (Other Adjustment), which means it is the provider's responsibility, not the patient's. Do not bill the patient unless the 835 CAS group code is PR.
What does CARC 11 look like on an EOB or 835 remittance?
On the 835 ERA, CARC 11 appears in Loop 2110 CAS segment as "CAS*CO*11*{amount}". On a paper EOB the same code prints in the Adjustment/Denial Reason column with the X12 description: "The diagnosis is inconsistent with the procedure." — usually paired with one or more RARC remark codes in the same remittance line for additional context.
Which RARC is paired with CARC 11?
CARC 11 is commonly observed with RARC N115, N130. The RARC narrows the reason — for example, pointing at a missing modifier, an LCD citation, or a specific policy. Fix the underlying CARC first; the RARC usually clears with the corrected claim.
Disclaimer
This page is operational reference for medical-billing professionals. It is not legal, clinical, or contractual advice. X12 code descriptors are maintained by the X12 External Code Lists; always verify against the current X12 release and the payer's own published policy before submitting or appealing a claim.