AI Invoice Extraction, Validation, and Approval Routing System - n8n Workflow

Finance and Accounting teams seeking to automate the Accounts Payable (AP) process.
Companies that need a high-accuracy, scalable n8n template for document understanding.
Users requiring complex business logic and flow control within an n8n workflow.
Technical professionals looking to integrate AI services like ScrapeGraphAI into an n8n node sequence.

Managing high volumes of incoming invoices is a tedious and error-prone process. This n8n workflow solves this by providing a unified, intelligent automation pipeline. It automatically receives invoices through two distinct n8n trigger mechanisms (Email and Webhook), uses specialized AI to extract structured data, and then applies critical business validation rules (e.g., duplicate checks, high-value thresholds, vendor approval). The core strength of this n8n automation is its dynamic routing: clean invoices proceed directly to the accounting system, while flagged or high-value invoices are sent through a multi-stage approval process via Telegram. This comprehensive n8n node sequence ensures high data quality, compliance, and significant time savings in AP operations, making it an essential n8n template for modern finance departments.

This n8n workflow executes in a linear, yet branching, path:

1. Trigger & Ingestion: The n8n workflow starts using either the Email Trigger (checking for attachments like PDFs/JPEGs) or the File Upload Webhook.


2. File Processing: The custom File Processor n8n node normalizes the input, extracts metadata (sender, date), filters for valid document types, and prepares the binary file data for AI analysis.


3. AI Extraction: The ScrapeGraphAI - Invoice Extractor n8n node reads the invoice image or PDF and extracts structured data such as line items, totals, and vendor details.


4. Cleaning & Scoring: The Data Extractor & Cleaner custom n8n node standardizes dates and amounts, calculates a data completeness score, and prepares the data for validation.


5. Validation Engine: The Validation Rules Engine n8n node applies crucial business logic: checking for required fields, verifying total amount calculations, flagging high-value invoices (>$10,000), and simulating duplicate detection. This determines if the invoice requires approval.


6. Approval Routing: The Approval Required? n8n node (a Switch node) checks the requires_approval flag.


7. Approval Generation (If Required): The Approval Workflow Generator n8n node creates a structured approval request, detailing reasons (e.g., High amount, New vendor), and formats a rich message using Markdown.


8. Notification & Integration: The Approval Notification n8n node sends the detailed request via Telegram. Regardless of whether approval was needed, the final step—the Accounting System Integration n8n node—sends the fully validated invoice data to a mock accounting system API.

To deploy this robust n8n workflow, follow these steps:

1. Import: Copy the provided JSON data and paste it into your n8n instance using the 'New' -> 'Import from JSON' option.


2. Set Up Triggers:

1. Configure ScrapeGraphAI: Ensure you have the ScrapeGraphAI n8n node installed and configured with the necessary API key for document extraction.


2. Set Up Telegram: Configure the Approval Notification n8n node with your Telegram Bot Token and specify the correct Chat ID or channel ID (@invoice_approvals) where approval messages should be sent.


3. Accounting Integration: Update the Accounting System Integration n8n node with the correct URL and authentication credentials for your target ERP or accounting system.


4. Activate: Save and activate the n8n workflow to start monitoring for incoming invoices.

Email Trigger (n8n trigger): Initiates the n8n workflow by polling an IMAP mailbox. It automatically pulls relevant attachments (PDFs, images) and passes them to the processor.
File Upload Webhook (n8n trigger): Provides a REST endpoint (/invoice-upload) for API-driven or manual file uploads, ensuring flexibility for the n8n workflow.
File Processor (Code n8n node): Essential logic for normalizing inputs from different triggers. It filters for file type compatibility and structures the metadata, creating separate execution items for each file.
ScrapeGraphAI - Invoice Extractor (Custom n8n node): The core AI component. It takes the binary file data and uses advanced LLMs and vision capabilities to return a structured JSON object containing all invoice fields.
Validation Rules Engine (Code n8n node): Executes complex, business-specific validation rules (e.g., amount consistency, duplicate check simulation). It calculates a validation score and sets the crucial requiresapproval flag for the subsequent n8n node.
Approval Required? (Switch n8n node): A critical flow control n8n node that routes the execution path based on the requiresapproval boolean.
Approval Workflow Generator (Code n8n node): If approval is required, this n8n node constructs a detailed, hierarchical approval message and workflow steps, ready for external communication.
Approval Notification (Telegram n8n node): Sends the rich, Markdown-formatted approval message generated by the previous n8n node to a secure Telegram channel for quick review and action.

• Accounting System Integration (HTTP Request n8n node): The final action, used to post the finalized, validated invoice data (including processing metadata) into an external accounting system, completing the n8n workflow.