Expense Claim Approval Workflow: Gemini + Google Sheets (n8n)

Approve expense claims automatically—or route them for manager review—using Gemini and Google Sheets in n8n

This Expense Claim Approval Workflow in n8n ingests expense receipts (via webhook upload or email/IMAP), extracts claim details with Google Gemini, checks policy rules and ledger history in Google Sheets, and then either auto-approves or emails a manager for approval—all while logging the final decision.

What this workflow does

• Receives receipts from a file upload webhook or an email inbox attachment.
• Splits and normalizes supported files (PDF or images), capturing the employee’s name and email from the webhook payload or email sender.
• Extracts expense claim fields with Google Gemini, including vendor, date, amount, tax, category, and an initial auto-approve flag.
• Applies policy + risk checks by reading thresholds and prior spend from Google Sheets to detect duplicates, compute employee/category metrics, and determine the final approval requirement.
• Logs to a Google Sheets ledger for every claim.
• If web-uploaded, returns an immediate JSON response indicating “Auto-Approved” or “Pending Approval.”
• If pending, sends a Gmail approval email with approve/reject links, then updates the ledger status and notifies the employee by email.
• Includes a separate webhook endpoint to look up a claim by ID and return its current approval status from Google Sheets.

Use cases

• Turn receipt uploads into real-time expense approvals without manual data entry.
• Route higher-risk or duplicate claims for manager approval with one-click Gmail links.
• Provide employees a clear workflow: submit receipts, then receive an email decision automatically.

Technical details

• n8n nodes/integrations: if, code, webhook, sticky note, Google Sheets, Gmail.
• APIs/credentials required: Google Gemini (PaLM/Gemini API), Google Sheets OAuth2, IMAP (email inbox attachments), Gmail OAuth2.