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Case studies Reference system

Automated invoice reminders

Overdue invoices are chased automatically, in the right tone, and the team is kept informed.

For
SMEs and operations, Agencies and firms
Service
Automate + AI
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Reference system: a need I come across often, documented with the exact architecture I would put in place. Other client work is presented in meetings.

01Problem

Every week, someone opens the list of invoices, spots the overdue ones, finds the right contact, writes a reminder and updates a spreadsheet.

It's repetitive, it gets forgotten as soon as the workload rises, and cash flow pays the price.

02Context

Users
Accounts, management and account managers.
Current process
Export from the invoicing software, manual sorting, emails one by one, tracking in a spreadsheet.
Constraints
No change of invoicing software, a tone suited to each client, the ability to pause a reminder at any time.
Tools in place
  • Invoicing software
  • Spreadsheet
  • Email
  • Slack

03Solution

An n8n workflow triggered by the invoicing software. It filters overdue invoices, pulls the client's context from Supabase, has the AI write a courteous reminder based on the history, sends it and notifies the team.

Every run is logged.

Why this approach. Automate the reminder, not the relationship: sensitive cases are flagged to a person instead of being chased.

04Architecture

Input

  • Invoicing The invoicing software reports each due date by webhook, or through a scheduled read of its API.

Automation

  • n8n · filters Keeps only overdue invoices, sets aside clients marked "sensitive" and amounts outside the rules.

Data

  • Supabase Client context: billing contact, reminder history, tone to use.

AI

  • Claude Writes a reminder suited to the history and to how late the payment is, without ever inventing an amount.

Output

  • Email The reminder is sent from the company's address to the billing contact.
  • Slack The team is notified, and sensitive cases are passed to it instead of being chased.

Interface

  • Report A weekly report of outstanding amounts and reminders sent.

05Features

  • Automatic triggerEvery overdue invoice starts the workflow, with no export or manual sorting.
  • Business filtersAmount, age, sensitive client: the rules are your company's own.
  • Reminder written from the historyThe tone changes with the delay and the relationship, never one single template.
  • Escalation to a personDelicate situations go to the right person instead of getting a reminder.
  • Run logEvery reminder is logged: who, when, what content.
  • Outstanding amounts reportA weekly view of what is still owed and what has been chased.

06Target result

  • No more forgotten reminders.
  • Weekly time spent on reminders close to zero.
  • A clear view of outstanding amounts.

How it is measured

  • Reminders sent without intervention
  • Average time to payment
  • Time spent on reminders each week

07What I do

  1. Mapping the current process
  2. Workflow design
  3. Invoicing API integration
  4. AI prompts and safety rules
  5. Notifications
  6. Production launch and documentation

Try it.

A working version of the system, with sample data. Nothing is pre-recorded: it all runs in your browser.

Workflow · Invoice reminders Simulation

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