n8n Bank Invoice Reconciliation with Postgres & Claude Review

Reconcile bank transactions to open invoices—then escalate borderline cases to Claude

This n8n workflow reconciles incoming bank transactions against open invoices and existing ERP payment records, persists results in Postgres, and alerts your finance team in Slack—with optional review by Anthropic Claude for borderline matches. It also returns a run summary as JSON to webhook callers so your automation stays transparent and auditable.

What this workflow does

• Triggers on demand, daily, or via webhook: runs via a manual trigger, a 06:00 daily schedule, or a POST webhook request.
• Guarantees idempotency with Postgres: ensures required Postgres tables exist, then loads previously reconciled bank transaction and invoice IDs to avoid duplicate processing.
• Fetches and normalizes source data: pulls open invoices and ERP payments from an ERP API, and bank transactions from a bank API—then normalizes all datasets into a consistent schema.
• Scores matches with a rules-based engine: validates API call success and classifies results, generating exceptions such as unmatched payments, overdue invoices, duplicates, and ERP conflicts.
• Uses Claude review for borderline matches (optional): sends borderline cases for approve/reject/escalate decisions, then applies outcomes using confidence/variance guardrails.
• Writes results and notifies only when needed: upserts matches, exceptions, and a run summary into Postgres. It can optionally post auto-matched payments back to the ERP with an idempotency key and sends a Slack alert only when review or exceptions exist.
• Returns results or fails safely: responds with a final JSON summary to webhook callers, or logs failure in Postgres and returns an HTTP 502 if source/API steps fail.

Use cases

• Automate daily invoice reconciliation using n8n and Postgres, reducing manual finance workload.
• Escalate uncertain matches to Anthropic Claude while keeping most reconciliations rules-based.
• Track reconciliation runs and exceptions for audit-ready reporting via webhook JSON responses.

Technical details

• n8n nodes: if, code, no op, merge, webhook, postgres.
• Integrations: ERP API, bank API, Postgres persistence, optional ERP updates with idempotency key, Slack notifications, and optional Anthropic Claude review.