Automate Invoice Processing in Microsoft 365 with GPT-4.1

Transform your invoice processing from a time-consuming manual task into a fully automated Microsoft 365 workflow. This n8n automation leverages GPT-4.1-mini to intelligently extract invoice data from your Outlook emails, organize PDF attachments in OneDrive, and maintain comprehensive Excel records—all without lifting a finger.

What this workflow does

Running daily at 7 AM, this automation monitors your designated Outlook folder for unread emails containing invoices. The workflow processes each email by cleaning HTML content to plain text and sending it to GPT-4.1-mini, which extracts 14 structured invoice fields including vendor name, invoice number, issue date, due date, and total amount due. When PDF attachments are detected, the system automatically creates dated OneDrive subfolders (Invoices/YYYY-MM-DD), uploads files using the naming convention VENDOR-YYYY-MM.pdf, and captures shareable links via Microsoft Graph API. All extracted data gets appended to your Excel tracking table, processed emails are marked as read, and a formatted HTML digest summarizing all invoices is delivered to your inbox.

Use cases

• Small business owners managing vendor invoices across multiple suppliers
• Finance teams requiring automated invoice data capture for accounting workflows
• Operations managers tracking recurring service payments and contract renewals
• Accounting departments eliminating manual data entry from email invoices
• Remote teams needing centralized invoice organization within Microsoft 365

Technical details

This workflow operates entirely within the Microsoft 365 ecosystem using Microsoft Outlook OAuth2 for email processing and Microsoft Graph OAuth2 for OneDrive and Excel integration. Built with essential n8n nodes including if, set, code, merge, filter, and sticky note components for robust invoice automation. The GPT-4.1-mini integration ensures accurate data extraction while maintaining compatibility with your existing Microsoft productivity suite.

Perfect for n8n users seeking to automate invoice processing workflows without third-party dependencies, this solution delivers enterprise-grade automation using familiar Microsoft tools your team already uses.