# CARC 109 Denial Code (Claim Not Covered by Payer / Sent to Wrong Contractor) | ANSI 835 EDI Spec
> Comprehensive healthcare EDI technical reference and denial resolution guide for Claim Adjustment Reason Code 109 (Claim Not Covered by Payer / Sent to Wrong Contractor) under ANSI ASC X12 835 005010X221A1.

- **Canonical URL:** https://stanzaapi.com/tools/x12-parser/carc/carc-109-wrong-payer-contractor
- **Governing Standard:** ANSI ASC X12 Standards (005010) (Accredited Standards Committee X12 / HIPAA 5010)
- **Edge Latency SLA:** <2ms Edge (Cloudflare V8 Isolates)
- **Execution Model:** Pure compute $f(x) = y$, 100% In-Memory (Zero Store, Zero Log)

## Technical Overview & Governing Rules
Claim Adjustment Reason Code (CARC) 109 communicates: "Claim not covered by this payer/contractor. You must send the claim to the correct contractor/payer.".

In ANSI X12 835 Electronic Remittance Advice (ERA) files, CARC 109 is reported in Loop 2110 (Service Payment Information) or Loop 2100 (Claim Payment Information) under the Claim Adjustment (CAS) segment with Group Code 'OA' (Other Adjustment), formatted as: CAS*OA*109*AMOUNT~.

Root Cause: Claim submitted to incorrect insurance entity (e.g. submitting Medicare Part B services to Part A MAC, or Medicaid HMO service to state fee-for-service).

Adjudication & Appeal Strategy: Update Payer ID in electronic billing system and submit fresh 837 to correct carrier.

## Specification Matrix
| Attribute | Value | Technical Guidance |
| --- | --- | --- |
| Reason Code | CARC 109 | Claim Not Covered by Payer / Sent to Wrong Contractor |
| Standard Group Code | OA | Other Adjustment |
| ANSI 835 Segment | CAS*OA*109*AMOUNT~ | Loop 2110 or Loop 2100 |
| Balance Billing Patient | Prohibited. | Compliance with billing regulations |
| Common RARCs | MA04 | Remittance Advice Remark Codes |
| Recommended Action | Update Payer ID in electronic billing system and submit fresh 837 to correct carrier. | Workflow for billing teams |

## Standard JSON Response Model
```json
{
  "transactionType": "835",
  "claimNumber": "CLM-2026-001",
  "adjudication": {
    "billedAmount": 500,
    "paidAmount": 0,
    "adjustments": [
      {
        "groupCode": "OA",
        "groupName": "Other Adjustment",
        "reasonCode": "109",
        "reasonDescription": "Claim Not Covered by Payer / Sent to Wrong Contractor",
        "adjustmentAmount": 500
      }
    ]
  }
}
```

## Frequently Asked Questions & Edge Cases
### Q: What does CARC 109 mean on an 835 ERA?
**A:** CARC 109 signifies: "Claim not covered by this payer/contractor. You must send the claim to the correct contractor/payer.". It explains why the payer did not pay the full billed charge.

### Q: Can a provider balance-bill the patient for CARC 109?
**A:** Prohibited.

### Q: How do medical billing teams resolve and appeal CARC 109?
**A:** Update Payer ID in electronic billing system and submit fresh 837 to correct carrier.