n8n WhatsApp Invoice Reminder Workflow (Google Sheets)

Get WhatsApp invoice reminders sent on schedule—automatically from your Google Sheets

Stop letting overdue invoices slip. This n8n WhatsApp Invoice Reminder Workflow (Google Sheets) automatically reads your open invoices, calculates how many days they’re overdue, and sends the right Hebrew WhatsApp reminder at 7, 14, and 30 days—with friendly-to-firmer messaging and full logging back to your sheet.

What this workflow does

• Runs daily: A Schedule Trigger fires every morning at 09:00.
• Loads open invoices: The workflow reads rows from your Google Sheet tab Invoices where Status = open.
• Calculates overdue days: A Code node computes days overdue and selects the reminder tier for exactly 7, 14, or 30 days.
• Prevents duplicate tier sends: It ensures a customer is never messaged twice for the same tier using LastReminder / LastReminderDate.
• Sends via WhatsApp: The reminder is sent through your WAHA server, with throttling to stay WhatsApp-friendly.
• Logs sends back to Google Sheets: Each message is recorded with the tier and date so your invoice tracking stays accurate.

Use cases

• You manage invoices in Google Sheets and want consistent follow-ups without manually chasing customers.
• You run a small business and need polite reminders early (7 days), firmer follow-up (14 days), and a final notice (30 days).
• You operate SaaS or manage ops and want a reliable n8n automation workflow that works with your existing sheet-based process.

Technical details

• Nodes / components: Schedule Trigger, Google Sheets, Code, HTTP request, and a Sticky Note.
• Required sheet tab/columns: Tab name Invoices with InvoiceID | CustomerName | Phone | Amount | DueDate | Status | LastReminder | LastReminderDate.
• WhatsApp integration: Send through WAHA using your HTTP node (update YOUR-WAHA-SERVER) and Header Auth with X-Api-Key.
• Customization: Update the three Hebrew reminder messages (and optionally the 7/14/30-day tiers) inside the Code node.

Built by Achiya Automation (https://achiya-automation.com).