Chasing an invoice is unpleasant. You tell yourself the client will pay, that they simply forgot, and the reminder waits. Three weeks later, your cash flow feels it. I have already covered automated quote follow-up, before the client signs. This article is about the next step: the invoice has gone out, the due date has passed, and the money has not arrived.
This tutorial describes the workflow I build with n8n, the automation tool I use most. If you are new to it, start with what n8n is and what it costs. If you are weighing it against Make or Zapier, the logic is the same, and my n8n vs Make vs Zapier comparison will help you pick.
In short. A reliable invoice list, one run every morning, four stages (day 1, day 8, day 15, day 30), emails sent from your own address, an automatic stop on payment, and a person for anything past 30 days.
What are the legal rules before chasing a B2B invoice in France?
The rules below are the French ones, for invoices between businesses. If you invoice from another country, your local rules apply instead, so check them before writing your templates. In France, they are summarized on the official service-public.gouv.fr page on payment terms between professionals and late-payment penalties (in French, checked on October 17, 2026):
| Rule | What the official page says |
|---|---|
| Default payment term | 30 days after delivery of the goods or completion of the service (article L441-10 of the French Commercial Code) |
| Maximum agreed term | 60 days from the invoice date, or 45 days end of month, if both parties agreed to it |
| Late-payment penalties | A rate of at least 3 times the French legal interest rate; if no other rate is agreed, the ECB rate plus 10 points |
| Fixed recovery fee | €40, due once per invoice paid late, to be stated in your terms of sale and on your invoices (article D441-5) |
| Invoice wording | The payment term must appear on the invoice (article L441-9) |
Two practical consequences for the automation. First, every invoice needs a due date, otherwise the workflow cannot know when to start. Second, from a certain stage, your emails can mention the penalties and the €40 fee, because the law provides for them: they are a reminder, not a threat. These rules apply to invoices between businesses, not to consumers. The exact rate changes every six months, so read it on the official page rather than copying it once.
What do you need in place before automating?
The workflow will never be more reliable than the list it reads. Same rule as for quotes: one place where invoices live, with an up-to-date status. In a Google Sheet, you need at least these columns:
- Invoice number and amount;
- Client and email of the person who pays (often accounts payable, not the person who ordered);
- Due date;
- Status: sent, paid, disputed;
- Last stage sent and date of the last reminder, filled in by the workflow;
- A "manual follow-up" checkbox: when ticked, the workflow skips the invoice.
If your invoices live in invoicing software, check first whether it has built-in reminders: they are often enough. n8n becomes useful when you want your own stages and wording, or when invoices come from several tools. The software can then stay the source of truth, read through its API (the interface that lets two programs exchange data) instead of a spreadsheet.
Which reminder stages should you plan?
Here is the sequence I suggest by default. Adjust it to your trade and your clients. The logic: each message goes up one notch, and the last one hands over to a person.
| Stage | When | Tone | Content |
|---|---|---|---|
| 1 | Day 1 after the due date | Polite | Simple reminder, invoice attached |
| 2 | Day 8 | Direct | Asks for a payment date |
| 3 | Day 15 | Firm | Mentions penalties and the fixed recovery fee |
| 4 | Day 30 | Internal | No email to the client: a task for you (call, then formal notice if needed) |
I never automate the formal notice. It is a letter with legal weight, it needs a careful read, and in France it usually goes by registered mail. The workflow tells you it is time to think about it; the decision stays yours.
How do you build the workflow in n8n, step by step?
The workflow fits in seven nodes (a node is a step in n8n). Throughout the build, replace the client email with your own address: no real client should ever receive a test.
1. The trigger: every weekday morning
Add a Schedule Trigger node, set to 9 a.m. Monday to Friday. Check your instance's time zone: the n8n documentation says the GENERIC_TIMEZONE variable sets the time used by scheduled triggers. Without it, your reminders may go out at 3 a.m.
2. Read the invoices
A Google Sheets node in read mode fetches every row. On screen, you should see one output item per invoice, with your column names as fields.
3. Keep only the invoices to chase
A Filter node keeps rows whose status is "sent", whose due date has passed and whose "manual follow-up" box is empty. Paid or disputed invoices drop out here: this is what stops the sequence as soon as the client pays.
4. Work out the delay and the stage due
A Code node (or Edit Fields with an expression) counts the days since the due date, then the expected stage: 1 from day 1, 2 from day 8, 3 from day 15, 4 from day 30. Compare it with the stage already sent: if they match, do nothing. This check prevents duplicates if the workflow runs twice on the same day.
5. Route to the right message
A Switch node sends each invoice to its stage's branch. Branches 1 to 3 email the client; branch 4 creates an alert for you.
6. Send from your own address
A Gmail (or Outlook) node sends the message, with the invoice attached if it is stored in Google Drive. The email comes from your address, with your signature, so the client replies to you directly. That reply is what you are after.
7. Log what was done
A last Google Sheets node updates the row: stage sent, reminder date. This log helps the day a client says they never received anything.
What about stopping on payment? It depends on the status being updated. By hand, it is a habit to build each time a transfer arrives. Automatically, you can match bank transfers with invoices: that is the topic of my article on automated bookkeeping with n8n, Pennylane and Qonto.
What do the reminder emails look like?
Two examples, for a cleaning company invoicing a business client. The bracketed variables are filled in by n8n from the spreadsheet.
FromYour usual address
ToClient's accounts payable
SubjectInvoice [number] now due
Day 1
Hello, unless I am mistaken, invoice [number] for [amount], due on [date], has not been paid yet. I have attached it again. If the payment is already on its way, please ignore this message.
Invoice-[number].pdf
FromYour usual address
ToClient's accounts payable
SubjectRe: Invoice [number], 15 days overdue
Day 15
Hello, invoice [number] is still unpaid 15 days after its due date. As stated in our terms of sale, late payment triggers late-payment penalties and a fixed recovery fee. Could you give me a payment date? If something on the invoice is a problem, just reply to this message.
The way out ("if something is a problem") matters as much as the reminder. An unpaid invoice often hides an unspoken objection: a missing purchase order, a wrong billing address. Better to learn it on day 15 than on day 60.
Which mistakes should you avoid with automated invoice reminders?
- Chasing an invoice that is already paid. This is the one that upsets clients, and it always comes from an outdated status. Keep "if the payment is on its way, ignore this message" in the early stages.
- Forgetting partial payments. A client who paid half should not get the same text. Add a "balance due" column and use it in the message.
- Testing on real clients. While you build, use an allowlist: only test addresses can receive an email. Remove it once everything is checked.
- Letting it run unwatched. A workflow can stop silently (expired Google access, renamed column). Set up an error alert: n8n lets you define an error workflow that notifies you.
If you would rather not build all this yourself, it is exactly the kind of project I take on in my business automation work: usually one to two weeks for invoice reminders, testing included, with documentation so someone else can take over the workflow.
When is it better not to automate invoice reminders?
- You send few invoices. With five invoices a month, a calendar reminder on the due date is enough.
- The invoice is disputed. An automated email in the middle of a disagreement about the work makes things worse. Mark it "disputed" to take it out of the sequence.
- The client is strategic. For a major client, a call beats any message, however well written.
- Your clients are consumers. The penalty and fee rules above apply to businesses. Adapt the wording before automating.
- The delay is past 30 days. That is the time for a formal notice or legal advice, not a fifth email.
Sources checked on October 17, 2026
- Service-public.gouv.fr (Entreprendre), payment terms between professionals and late-payment penalties (French)
- n8n, installation documentation (GENERIC_TIMEZONE variable)
- n8n, Google Sheets integration and Gmail integration
Frequently asked questions
Can you automate unpaid invoice reminders for free?
Yes, if you install the Community edition of n8n on your own server: the software is free for internal use, and you pay for the server and the maintenance time. The hosted version of n8n is paid.
How many reminders should you send for an unpaid invoice?
Three emails are usually enough: a polite reminder right after the due date, a request for a payment date a week later, then a reminder of the penalties. After 30 days, a call or a formal notice works better than another email.
Should the reminder mention the €40 recovery fee?
Under French rules, between businesses, the €40 fixed recovery fee is due once per invoice paid late and must already appear in your terms and on your invoices. Mentioning it in a firm reminder is useful, just not as the opening line.
How do the reminders stop once the client has paid?
The workflow only chases invoices with the status sent. As soon as the status changes to paid, by hand or through automatic matching with your bank, the invoice leaves the sequence the next morning.
Does it work with Pennylane or other invoicing software?
Yes, as long as the software gives access to its invoices through an API. n8n then reads invoices and their status directly, with no spreadsheet. First check whether the software already has its own reminders: sometimes that is enough.