Automate Invoices & Payment Reminders with n8n Workflow

Transform your invoicing process from manual chaos to automated precision with this comprehensive n8n workflow that handles everything from PDF invoice generation to payment tracking and follow-up reminders.

What this workflow does

This intelligent automation system streamlines your entire invoice lifecycle using Google Sheets as your central hub. When you add a new client invoice row, the workflow automatically generates a professional HTML invoice, converts it to PDF using PDFShift API, and leverages Groq LLM to craft personalized email content. Your invoice gets sent via Gmail with the PDF attachment, while your Google Sheet updates to track status and send dates.

The workflow runs daily at 9am to monitor unpaid invoices, automatically calculating overdue days and routing clients through strategic reminder sequences at 7, 14, and 30-day intervals. Each reminder uses Groq to generate contextually appropriate follow-up emails, sends notifications to your Telegram, and updates tracking data in your spreadsheet.

Payment processing becomes effortless with Telegram command integration. Simply message "paid [client name]" and the workflow instantly marks invoices as paid, sends automated thank-you emails via Gmail, and confirms the update back to Telegram.

Use cases

• Freelancers and consultants managing client billing cycles
• Small agencies automating invoice workflows without expensive software
• SaaS operators handling subscription billing reminders
• Service businesses streamlining accounts receivable processes
• E-commerce businesses managing B2B payment collections

Technical details

Built with essential n8n nodes including if, set, code, html, gmail, and merge nodes. Integrates seamlessly with Google Sheets for data management, PDFShift for professional PDF generation, Groq LLM for intelligent email drafting, Gmail for reliable email delivery, and Telegram for instant mobile notifications and commands.

This workflow eliminates manual invoice tracking, reduces payment delays through consistent follow-ups, and provides complete visibility into your invoicing pipeline—all while maintaining professional client communications.