Send overdue invoice reminders from Pennylane to Slack

Who is this for

Finance teams and freelancers using Pennylane (French accounting platform) who want daily alerts for unpaid invoices that need follow-up.

What it does

This workflow runs daily at 9 AM, fetches all customer invoices from Pennylane, and identifies unpaid invoices past their deadline by 7 or more days. If overdue invoices are found, it sends a detailed Slack reminder with invoice number, amount, days overdue, and a direct link to the PDF. If no invoices are overdue, the workflow ends silently.

How to set up

1. Import this workflow into n8n
2. Create a Header Auth credential with name Authorization and value Bearer <YOUR_PENNYLANE_TOKEN>
3. Select your Slack channel in the SL Send Notification node
4. Adjust the schedule time in the Schedule Trigger node if needed

Requirements

• Pennylane account with API access (Essentiel plan or higher)
• Pennylane API token with scope: customer_invoices:all
• (Optional) Slack workspace for notifications

How to customize

• Change THRESHOLD_DAYS in the Code Filter Overdue node to adjust when reminders trigger (default: 7 days past deadline)
• Change the schedule time in the Schedule Trigger node (default: 9 AM daily)
• Replace Slack with Telegram, Email, or any other notification channel

Part of a 3-workflow billing automation suite: https://github.com/Gauthier-Huguenin/n8n-pennylane-auto-invoicing