n8n Invoice Management System with Gmail Reminders, Google Sheets, and Slack Escalations

This n8n workflow automates the process of managing invoices, sending reminders via Gmail, tracking them in Google Sheets, and escalating overdue invoices to Slack. It's designed to streamline your accounts receivable process and ensure timely payments.

What it does

This workflow simplifies invoice management through the following steps:

1. Triggers on Schedule: The workflow starts on a predefined schedule (e.g., daily) to check for invoices.
2. Fetches Invoice Data: It retrieves invoice data from a specified Google Sheet.
3. Processes Invoices in Batches: Each invoice item is processed individually to manage reminders and escalations efficiently.
4. Sets Invoice Data: It prepares the invoice data for further processing, extracting relevant fields like invoiceId, customerEmail, dueDate, amount, and status.
5. Conditional Logic for Overdue Invoices:
   • If invoice is overdue:
     • Sends Gmail Reminder: An email reminder is sent to the customer.
     • Updates Google Sheet: The status of the invoice in the Google Sheet is updated to "Reminder Sent".
     • Escalates to Slack: A notification is sent to a designated Slack channel to alert about the overdue invoice.
   • If invoice is not overdue:
     • The workflow continues without taking any action for that specific invoice.
6. Responds to Webhook (Optional/Placeholder): The workflow includes a "Respond to Webhook" node, which could be used to provide a response if this workflow were triggered by an external webhook, though in its current state, it's triggered by a schedule.
7. Aggregates Data (Optional/Placeholder): The "Aggregate" and "Split Out" nodes suggest potential for more complex data manipulation or processing of multiple outputs, but they are not actively connected in the provided JSON.

Prerequisites/Requirements

To use this workflow, you will need:

• n8n Instance: A running instance of n8n.
• Google Account: For Google Sheets and Gmail integration.
  • Google Sheets Credential: Configured in n8n to access your invoice spreadsheet.
  • Gmail Credential: Configured in n8n to send reminder emails.
• Slack Account: For sending escalation notifications.
  • Slack Credential: Configured in n8n to post messages to a channel.
• Google Sheet: A Google Sheet containing your invoice data with columns for invoiceId, customerEmail, dueDate, amount, and status.

Setup/Usage

1. Import the Workflow:
   • Copy the provided JSON workflow.
   • In your n8n instance, click "New" to create a new workflow.
   • Go to "File" > "Import from JSON" and paste the copied JSON.
2. Configure Credentials:
   • Locate the "Google Sheets" node and configure your Google Sheets credential.
   • Locate the "Gmail" node and configure your Gmail credential.
   • Locate the "Slack" node and configure your Slack credential.
3. Update Node Settings:
   • Google Sheets (Node 18):
     • Specify the Spreadsheet ID and Sheet Name where your invoice data is stored.
     • Ensure the "Read All" operation is configured to fetch all relevant invoice data.
   • Edit Fields (Set - Node 38):
     • Verify the field names (invoiceId, customerEmail, dueDate, amount, status) match your Google Sheet column headers. Adjust if necessary.
   • Switch (Node 112):
     • Review the conditions for identifying overdue invoices. This typically involves comparing the dueDate with the current date.
   • Gmail (Node 356):
     • Customize the email subject and body for the reminder. Use expressions to dynamically insert invoice details (e.g., {{ $json.invoiceId }}, {{ $json.amount }}).
   • Google Sheets (Update - Node 18, likely a second instance):
     • Configure this node to update the status column of the specific invoice row to "Reminder Sent" after an email is dispatched.
   • Slack (Node 40):
     • Specify the Channel where overdue invoice alerts should be posted.
     • Customize the Slack message to include relevant invoice details.
   • Schedule Trigger (Node 839):
     • Set the desired interval for the workflow to run (e.g., daily, weekly).
4. Activate the Workflow: Once all configurations are complete, activate the workflow to enable it to run automatically on schedule.