n8n Workflow: Google Sheets Invoice Reminder Emails via Gmail

Automate overdue invoice reminders with n8n + Google Sheets + Gmail

Stop manually chasing payments. This n8n Workflow automatically checks your Google Sheets invoices every weekday at 09:00 and sends payment reminder emails via Gmail at 3, 7, and 14 days past due, updating your invoice records and writing an audit trail to a Log tab.

What this workflow does

• Schedules reminders: Runs every weekday at 09:00.
• Reads invoice data: Loads reminder settings (cadence days, minimum gap between reminders, and a per-run safety cap) and scans the Invoices tab.
• Selects the right invoices: Targets invoices that are overdue by the next configured reminder day, skips closed/paid statuses, validates required fields (like customer email, amount, and due date), and avoids reminding customers too frequently.
• Sends staged Gmail emails: Builds a personalized email subject and body (optionally including a payment link) and sends the reminder through Gmail.
• Updates tracking fields: Writes back status, attempts, last reminder date, and computed next reminder date to the matching row.
• Creates an audit log: Appends a row to the Log tab for each successfully sent reminder.

Use cases

• SaaS operators sending automated payment nudges for overdue invoices stored in Google Sheets
• Operations teams reducing late payments without building a full billing system
• n8n users who need clear invoice status updates and email send auditing

Technical details

• Integrations: Google Sheets (read, update, and log) and Gmail (send reminders)
• Nodes used: if, set, code, no op, gmail, filter
• Expected sheet tabs/fields: An Invoices tab with columns including invoice_id, customer_email, customer_name, amount, currency, due_date, status, attempts, last_reminder_at, next_reminder_at, plus relevant settings/logging fields, and a Log tab for audit entries