A client who lets your invoice drag on isn't always acting in bad faith. Often your email got buried under a pile of others, the invoice is waiting on an internal sign-off, or the person simply forgot. The problem is that the follow-up makes you uncomfortable: you don't want to come across as the pushy supplier, but you want your money. So you keep putting it off, the unpaid invoice settles in, and your cash flow takes the hit. This article gives you a clear method for writing an unpaid invoice reminder email that stays firm on substance and courteous in tone, with ready-to-copy templates and the right sending rhythm. You'll see how AI can draft your reminder in thirty seconds, which words to avoid so you don't put people's backs up, and what French law lets you claim on top of the amount owed. The goal is simple: get paid without breaking the relationship.
Why a badly worded reminder costs more than waiting
An effective reminder stays short, factual and polite: it recalls the facts without accusing or threatening in the very first message. Most late payments get sorted with a well-worded email, as long as you don't start off on the wrong foot.
The classic mistake is writing in the heat of annoyance. A sentence like "I'm surprised I still haven't been paid" immediately puts the client in the wrong. If they'd simply forgotten, you've just turned an oversight into tension. And if the delay comes from a real problem on their end (a slow accounts department, a missing document), you look like someone who accuses before understanding.
A good reminder does three things: it recalls the precise invoice details (number, amount, due date), it offers an easy way out ("the invoice may have slipped through unnoticed"), and it asks for a clear action ("can you confirm the payment date?"). You stay in control of the tone, you keep the relationship, and you get a faster reply. That's exactly what the templates and tools below do.
Method 1: let a guided agent from the Skilzy Lab write your reminder
The fastest option is to describe your situation to a guided AI that asks you two or three questions, then drafts the email for you, right tone included. No template to hunt down, no wording to weigh up: you answer, it writes.
In the Skilzy AI Lab, the Guided tab offers mini agents designed for concrete everyday work situations. The "A tricky email" card is made exactly for this: you say you want to chase a client about a late invoice, you specify the amount, the due date and how firm you want to be, and the agent hands you a ready-to-send email.
When you're starting out, the benefit is not getting stuck in front of a blank page or a prompt you have to write yourself. The agent guides you, and you tweak a couple of words if needed. You can ask it for three versions: a gentle reminder, a firm reminder and a formal notice. You keep the right one, personalise the first name and the invoice number, and send.
To try it without pulling out your card, the Skilzy discovery demo gives you 7 days of access with 1 image, 1 video, 1 music track and 10 messages, no bank card required. Ten messages is plenty to draft and fine-tune a full reminder sequence. And if managing your clients becomes a real topic, the become an AI freelancer programme teaches you to use these tools day to day to invoice, chase and track your business without spending your evenings on it.
This approach combines well with the rest of your setup: if you want to scale up your sending, read our guide to automating your emails with AI.
Method 2: start from a reminder email template to personalise
If you'd rather keep full control, a good reminder email template always follows the same structure: clear subject line, recap of the facts, precise request, courteous sign-off. Here's a template you can copy as is and adapt.
Subject: Invoice no. 2026-084: friendly reminder
Hi [First name],
I hope you're doing well. Just a quick reminder about invoice no. 2026-084, for 1,200 euros, due on 10 August. It may have slipped through unnoticed on your end. You'll find it attached. Could you confirm the expected payment date?
Thanks a lot and have a great day, [Your signature]
The tone hardens very gradually across the reminders. Here's how to adapt the same email depending on the stage:
| Stage | Tone | Key phrase |
|---|---|---|
| Reminder 1 | Friendly | "It may have slipped through unnoticed." |
| Reminder 2 | Neutral and factual | "Unless I'm mistaken, this invoice remains unpaid to date." |
| Reminder 3 | Firm | "Without payment within 8 days, I'll be forced to apply the penalties provided for." |
Always keep the subject line precise, with the invoice number: it makes the email easy to find and looks serious. Avoid capital letters, multiple exclamation marks and passive-aggressive phrasing. A well-written template saves you from reinventing the wheel for every client, but remember to adjust it: a copy-pasted email with the wrong first name makes a bad impression.
Method 3: automate reminders with your invoicing software
Most invoicing software includes a free automatic reminder feature that sends an email on your behalf on dates you set. If you issue a lot of invoices, this is the most time-saving option.
Tools like a standard invoicing app (often bundled with your accounting package or management tool) let you schedule a sequence: a reminder the day before the due date, another 3 days later, a final one at 15 days. The system sends the emails, attaches the invoice and stops the sequence as soon as the payment lands. You don't have to lift a finger unless a client replies directly.
The limit of this method is the tone: automated messages are generic and sometimes cold. For a big strategic client, a manual, personalised reminder is still preferable. The best practice is to combine the two: automation for the routine flow, a hand-written email (with or without AI) for sensitive cases.
If you want to go further with automating your operations, our article on automating your business with AI breaks down the building blocks to connect invoicing, reminders and tracking.
The right reminder sequence: how many emails and at what pace
Three to four spaced-out reminders are enough in the vast majority of cases, ramping up in firmness without ever insulting the client. Too many reminders close together are annoying; too few let the unpaid invoice settle in.
Here's a sequence that works for a business-to-business invoice:
- D+3 after the due date: first reminder, friendly tone. You assume it's an oversight.
- D+10: second reminder, neutral and factual tone. You recall the due date and ask for a firm payment date.
- D+20: third reminder, firm tone. You mention late-payment penalties and offer a call to unblock the situation.
- D+30: formal notice by email (and ideally by registered letter). This is the last step before proceedings.
Between two emails, a short phone call often changes everything: it shows you're following the file closely and it lets you understand any hold-up. Keep a written record of each exchange: in the event of a dispute, this history counts. And never wait two months to send the first reminder; the longer you delay, the more normal the unpaid invoice looks to the client.
What French law lets you claim
Any business-to-business invoice paid late gives rise to late-payment penalties and a flat 40-euro recovery-cost indemnity, provided for by the French Commercial Code. Mentioning this in your firm reminder isn't aggressive at all: it's your right.
In practice, from the day after the due date you can apply late-payment penalties (the rate must appear on your invoice; failing an agreement, a legal reference rate applies). On top of that comes a flat 40-euro indemnity per invoice to cover your recovery costs, automatically due for any late business payment. You can check the official rules on late-payment penalties between businesses and the provisions on the flat 40-euro indemnity on the public websites.
Only use these mentions from the third reminder onward, so you don't dramatise too early. Politely pointing out that the law provides for these charges is often enough to unblock a payment, without you actually having to invoice them. If the client stays silent after the formal notice, you can consider an order to pay (injonction de payer), a simple and low-cost procedure for undisputed debts.
Conclusion
Chasing an unpaid invoice is not a confrontation: it's a sequence of calm, precise and increasingly firm messages. Choose your method based on your time and the number of invoices: a guided AI to draft quickly and well, a template to personalise if you like keeping control, or your software's automation for the routine flow. Apply the right sequence, keep your written records, and cite your rights at the right moment. You'll be paid faster, and your clients will keep working with you.
