Invoice Intake & Anomaly Detection
Catches invoice math errors and duplicate payments before they cost money, with zero manual data entry.
n8nGeminiGmail APIGoogle SheetsSlack
Problem
Meridian Advisory processes vendor invoices by hand: someone opens each emailed PDF, retypes the totals into a spreadsheet, and eyeballs the numbers. Two failure modes recur and both cost real money when missed, line items that don't add up to the stated total, and the same invoice getting paid twice because it was re-sent.
Key Features
- Watches a Gmail inbox for PDF invoices, no manual upload step
- Gemini extracts invoice number, vendor, totals, and dates as structured fields
- Recalculates the line item sum independently and flags any mismatch down to the exact dollar difference
- Duplicate invoice numbers are caught and filed to a separate audit tab, never double logged
- Only a genuine anomaly triggers a Slack alert, valid invoices log silently so the channel stays useful
- Every invoice lands in one sortable Google Sheet with status and a processed timestamp
Outcome
This replaced a manual review step that depended on someone catching a bad total by eye. Every invoice now gets checked the same way, every time, and the only thing that reaches a human is something that actually needs a decision.