# 835 — Remittance Advice (ERA)

The 835 transaction carries Electronic Remittance Advice — payment and adjustment details from a payer in response to submitted claims. RCMbox provides a built-in mapping activity (`map-835-to-claim-responses`) that converts parsed 835 data into FHIR `ClaimResponse` resources.

## What the built-in mapping extracts

- **CLP loop** — each claim-level payment becomes a draft `ClaimResponse`
- **CAS segments** — Claim Adjustment Reason Codes (CARC) mapped to adjudication entries
- **LQ segments** — Remittance Advice Remark Codes (RARC) for additional context
- **SVC segments** — service line detail with charged, paid, and allowed amounts
- **Contained resources** — Patient (from QC NM1), Payer (from 1000A), Payee (from 1000B)
- **Identifiers** — Patient Control Number (PCN), payer claim control number

## Used in

- [Upload ERA](../workflows/upload-era.md) workflow
- [Link ClaimResponse](../workflows/link-claim-response.md) workflow (downstream)