{"product_id":"n8n-expense-audit-automation-gpt-4o-slack-google-sheets","title":"n8n Expense Audit Automation: GPT-4o, Slack \u0026 Google Sheets","description":"\u003ch3\u003eAutomate Expense Audits in n8n—From Receipt OCR to Slack Review \u0026amp; Google Sheets Ledger\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow automatically audits employee expense submissions using \u003cstrong\u003eGPT-4o\u003c\/strong\u003e: it extracts receipt details, applies policy checks, sends exceptions to \u003cstrong\u003eSlack\u003c\/strong\u003e for manager review, auto-approves compliant expenses via \u003cstrong\u003eGmail\u003c\/strong\u003e, and logs every outcome to \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReceives submissions via a webhook\u003c\/strong\u003e with employee details and \u003cem\u003ereceipt OCR text\u003c\/em\u003e (e.g., fields like \u003ccode\u003eemployee\u003c\/code\u003e and \u003ccode\u003ereceipt_text\u003c\/code\u003e in the request body).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUses OpenAI GPT-4o to extract structured data\u003c\/strong\u003e from the receipt OCR text—capturing vendor, amount, currency, category, date, and whether the receipt is itemized.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eApplies company policy rules\u003c\/strong\u003e to detect issues such as over-limit spending or missing itemization, and attaches clear violation reasons to the expense record.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGenerates an audit verdict with GPT-4o\u003c\/strong\u003e including approve\/flag\/reject status, risk level, and a short reviewer note.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRoutes results automatically\u003c\/strong\u003e:\n    \u003cul\u003e\n      \u003cli\u003eIf the verdict is \u003cstrong\u003enot “approve”\u003c\/strong\u003e, it posts a flagged expense summary to a configured \u003cstrong\u003eSlack\u003c\/strong\u003e channel (e.g., \u003ccode\u003e#expense-approvals\u003c\/code\u003e).\u003c\/li\u003e\n      \u003cli\u003eIf compliant, it sends an \u003cstrong\u003eauto-approval email\u003c\/strong\u003e to the employee using \u003cstrong\u003eGmail\u003c\/strong\u003e.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLogs everything to Google Sheets\u003c\/strong\u003e, appending expense details and the audit outcome to a ledger, then returns a JSON acknowledgment to the webhook caller.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eCut down manual expense review by routing only exceptions to Slack.\u003c\/li\u003e\n  \u003cli\u003eStandardize receipt parsing and compliance decisions with GPT-4o-based extraction and verdicting.\u003c\/li\u003e\n  \u003cli\u003eMaintain an auditable expense ledger in Google Sheets for reporting and reconciliation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations\/nodes:\u003c\/strong\u003e Webhook, OpenAI (GPT-4o) via credentials, Slack, Gmail, Google Sheets, plus logic\/control nodes (e.g., \u003cstrong\u003eif\u003c\/strong\u003e, \u003cstrong\u003ecode\u003c\/strong\u003e, and a \u003cstrong\u003esticky note\u003c\/strong\u003e for guidance).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSetup highlights:\u003c\/strong\u003e enable the webhook endpoint, configure OpenAI credentials for GPT-4o in both receipt extraction and compliance verdict steps, and set the Slack target channel.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":45869895844019,"sku":"N8N-18439","price":46.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/DkwKZfmat-Gin0qkaAjYf_CaCBgO3i.png?v=1787130498","url":"https:\/\/buyflowscripts.com\/products\/n8n-expense-audit-automation-gpt-4o-slack-google-sheets","provider":"N8N Commerce","version":"1.0","type":"link"}