Send staged invoice payment reminders from Google Sheets via Gmail

Quick overview

This workflow runs every weekday at 09:00, reads overdue invoices from a Google Sheets spreadsheet, sends staged payment reminder emails via Gmail at 3, 7, and 14 days past due, then updates the invoice tracking fields and appends an audit entry to a Log sheet.

How it works

1. Runs every weekday at 09:00 on a schedule.
2. Loads reminder settings (cadence days, minimum gap between reminders, and a per-run safety cap) and reads all rows from the Google Sheets “Invoices” tab.
3. Selects invoices that are overdue by the next configured reminder day, skips closed/paid statuses, validates required fields (email, amount, due date), and avoids reminding customers too frequently.
4. Builds a personalized email subject and body (including an optional payment link) and sends the reminder through Gmail.
5. Updates the matching invoice row in Google Sheets with the new status, attempts count, last reminder date, and computed next reminder date.
6. Appends a row to the Google Sheets “Log” tab for each successfully sent reminder.

Setup

1. Connect a Gmail account/credential that is allowed to send reminder emails.
2. Connect Google Sheets credentials and paste your spreadsheet URL into the Google Sheets nodes that read, update, and log data.
3. Ensure your spreadsheet includes an “Invoices” tab with columns used by the workflow (at minimum: invoice_id, customer_email, customer_name, amount, currency, due_date, status, attempts, last_reminder_at, next_reminder_at, invoice_link) and a “Log” tab with matching log columns.
4. In “Your Settings”, set your display name and adjust reminder_days, min_gap_days, and max_per_run as needed, and leave test_today blank for production use.