Automate invoice processing with AI data extraction, Google Drive & Sheets

🧾 Automated Invoice Processing - n8n Workflow

📖 Workflow Description

This n8n workflow automates the complete processing of PDF invoices with AI-powered data extraction. The workflow monitors a Google Drive folder, extracts important invoice data, and automatically organizes files in a structured filing system.

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🎯 Features

• 🔍 Automatic monitoring of a Google Drive folder for new PDF files
• 🤖 AI-powered data extraction from invoices (customer, amount, date, etc.)
• 📁 Intelligent file sorting by year and month
• 📝 Automatic renaming following a consistent schema
• 📊 Central documentation in Google Sheets

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🔧 Required Integrations

Required Accounts:

• Google Drive (with folder permissions)
• Google Sheets (with write permissions)
• Google Gemini API (for AI data extraction)

Used n8n Nodes:

• Google Drive Trigger
• Google Drive (File Operations)
• Google Sheets
• Extract from File (PDF)
• Information Extractor (LangChain)
• Google Gemini Chat Model
• Split in Batches

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📋 Workflow Steps in Detail

1. Monitoring & Triggering

• Google Drive Trigger monitors a defined input folder
• Automatically starts when new PDF files are detected
• Split in Batches enables batch processing of multiple files

2. File Processing

• GetFile downloads PDF files from Google Drive
• ExtractFromPDF converts PDF content to text
• Supports scanned documents as well

3. AI Data Extraction

The Information Extractor node with Google Gemini extracts:

• Company name/sender
• Customer name and customer number
• Invoice number and date
• Net and gross amount
• Value-added tax
• Article description
• Month and year (for sorting)

4. Automatic Filing

• GetYearFolder searches/creates year folders
• GetMonthFolder searches/creates month folders
• MoveFile moves invoice to correct folder
• UpdateFileName renames file (schema: "Customer Month Year")

5. Documentation

• AddToOverview enters all data into Google Sheets table
• Enables central overview and analysis

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⚙️ Setup Instructions

Step 1: Prepare Google Drive

Create the following folder structure in Google Drive:

📁 [Input Folder] (e.g., "Invoices-Inbox")
📁 [Main Folder] (e.g., "Accounting")
   └── 📁 2024
       ├── 📁 January
       ├── 📁 February
       ├── 📁 March
       └── ... (all months)
   └── 📁 2025
       └── ... (all months)

Step 2: Create Google Sheets Table

Create a spreadsheet with the following columns:

• Customer Number
• Customer
• [Company Name] Location
• Invoice Date
• Invoice Number
• VAT
• Net Amount
• Month
• Year

Step 3: Configure Workflow

Configure Google Drive Trigger:

• Select your input folder as "Folder to Watch"
• Set "Event" to "fileCreated"
• Activate the trigger

Search files and folders:

• Select the same input folder as filter

Customize Information Extractor:

• Adapt attribute names to your needs
• Change company name in description
• Adjust system prompt if needed

GetYearFolder & GetMonthFolder:

• Set the correct folder ID for your main folder
• Check query string for year/month search

AddToOverview:

• Select your Google Sheets table
• Map columns according to your table

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🔧 Customization Options

Extend Data Extraction:

Add more attributes in the Information Extractor node:

{
  "name": "Payment Terms",
  "description": "Days until payment due",
  "required": false
}

Customize File Naming:

Change the schema in the UpdateFileName node:

"{{ $('Information Extractor').item.json.output.InvoiceNumber }} - {{ $('Information Extractor').item.json.output.Customer }}"

Change Monitoring Interval:

In Google Drive Trigger under "Poll Times" select different intervals.

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🚨 Important Notes

⚠️ Permissions:

• Google Drive: Full access to configured folders
• Google Sheets: Write permission for target table
• Google Gemini: Valid API key required

📝 Data Format:

• Works with German number formats (comma as decimal separator)
• Date format: YYYY-MM-DD
• Supports various PDF formats

🔄 Error Handling:

• Workflow fails if folders are missing
• Incomplete PDFs may lead to incomplete extractions
• Check logs for troubleshooting

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📊 Performance & Limitations

• Processing time: 30-60 seconds per invoice
• Supported formats: PDF (text and OCR)
• Batch processing: Yes, multiple files simultaneously
• AI accuracy: ~95% for standardized invoices

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🧪 Testing

1. Run Test:

   • Upload a test PDF to the input folder
   • Monitor workflow execution in n8n
   • Check results in Google Sheets
   • Verify correct file movement and renaming

2. Error Diagnosis:

   • For errors: check n8n logs
   • Consider Google API quotas
   • Validate folder permissions

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📄 License & Support

This workflow can be used and customized freely. For configuration questions or issues, check the n8n community or Google API documentation.

Tip: Start with a few test invoices before using the workflow in production!