n8n Monthly Google Sheets Invoice PDFs: Gmail, Drive & Slack

Automatically generate monthly Google Sheets invoice PDFs, archive them to Drive, email via Gmail, and notify Slack

This n8n workflow reads billable line items from your Google Sheets every month, creates one PDF invoice per client using Emitforge, stores each PDF in Google Drive, emails it to clients through Gmail, and posts a Slack summary for every invoice—fully automated, schedule-based, and audit-friendly.

What this workflow does

• Runs monthly on the 1st to process the previous month’s billable rows.
• Loads invoice defaults (company name, tax rate, and payment terms) and reads line items from Google Sheets (e.g., client, client_email, description, qty, unit_price).
• Groups rows by client, then calculates subtotals, tax, and totals for each client’s invoice.
• Builds an invoice HTML table for each client and sends it to the Emitforge PDF API.
• Retrieves a signed URL for the rendered PDF, downloads it, and archives the PDF to Google Drive in your selected folder.
• Emails the invoice PDF to each client using Gmail.
• Posts a per-invoice message to Slack including invoice number, client, total, and line count.

Use cases

• Service businesses invoicing multiple clients from a shared Google Sheets timesheet or billing tracker.
• SaaS operators who want monthly recurring invoices without manually exporting PDFs.
• Teams that need a consistent workflow: generate → store → email → Slack notify, all from Google Sheets data.

Technical details

• Scheduler: runs on the 1st of each month
• Integrations/Nodes: set, code, gmail, slack, google drive, and supporting elements like a sticky note
• PDF generation: Emitforge PDF API (configured via HTTP Header Auth, e.g., Authorization: Bearer <API_KEY>)