n8n Workflow: Google Sheets Overdue Invoice Chaser via Gmail

Never miss an overdue invoice again—automatically

This n8n workflow scans your Google Sheets invoice ledger every weekday morning, detects invoices that are truly overdue, and sends staged reminder emails via Gmail—while logging actions and capturing problematic rows for review.

What this workflow does

• Schedules: Runs at 9:00 AM, Monday through Friday.
• Reads invoice data: Pulls all rows from the Invoices tab in your Google Sheets spreadsheet.
• Filters and validates: Excludes settled or already-chased invoices, de-duplicates invoice_number, and validates due dates, amounts, and email fields.
• Calculates urgency: Computes days overdue and assigns each invoice to a bucket: gentle (1–7 days), firm (8–30 days), escalate, or needs review.
• Sends reminders via Gmail:
  • 1–7 days overdue: Sends a gentle reminder email.
  • 8–30 days overdue: Sends a firmer reminder email.
  • More than 30 days overdue: Emails you (internal escalation) instead of the customer.
• Logs and exceptions: Appends each chase to Chase Log and writes unreadable/problematic invoice rows to the Exceptions tab.

Use cases

• SaaS and service businesses that track invoices in Google Sheets and need consistent overdue follow-ups.
• Teams who want automated reminders with safeguards for settled, duplicate, or malformed invoice records.
• Operators who prefer internal escalation after 30 days overdue to avoid customer-facing delays.

Technical details

• Tech stack / nodes: schedule trigger, google sheets, gmail, code, switch, and sticky note.
• Required headers in Invoices: invoice_number, customer_name, customer_email, amount_due, currency, due_date, status, last_chased_at.
• Setup: Connect Google Sheets credentials and Gmail credentials, then paste your spreadsheet URL into all Google Sheets nodes.