n8n Google Sheets Invoice Price Compliance + Telegram Alerts

Instantly detect invoice price overcharges in Google Sheets and alert your team via Telegram

This n8n workflow automatically monitors a Google Sheets Invoices tab, compares each new invoice line’s Invoiced Unit Price ($) against the agreed Contract Prices, logs results for audit purposes, and sends Telegram alerts only for overcharges or unknown item codes.

What this workflow does

• Triggers every minute when a new row is added to the Invoices sheet (Google Sheets Trigger).
• Reads the Contract Prices tab from the same Google Sheets document.
• Matches invoice lines to contract lines by Item Code.
• Calculates price difference, overcharge amount, and a status:
  • OK
  • OVERCHARGED
  • Undercharged - Check
  • Item Not Found - Verify Code
• Appends the evaluated line and status to an Overcharge Report tab to maintain an audit trail.
• Sends a formatted Telegram message only when the status is OVERCHARGED or Item Not Found - Verify Code; otherwise it ends silently.

Use cases

• SaaS operators reconciling vendor invoices against contract pricing in near real-time.
• Automation engineers implementing Google Sheets-based compliance checks with n8n and Telegram notifications.
• Procurement teams flagging suspect invoices and missing Item Codes for quick verification.

Technical details

• Google Sheets Trigger (new rows in Invoices) and Google Sheets node (reads Contract Prices, writes to Overcharge Report).
• Logic nodes including if and code for matching by Item Code and computing overcharges.
• Telegram node for alerts to a configured chat ID.
• Includes supporting workflow elements such as no op and sticky note for workflow clarity.

Setup note: Ensure your sheet headers match the fields used for matching and calculations (e.g., Item Code, Invoiced Unit Price ($), Quantity, and Agreed Price ($)).