You spend your Sunday evenings retyping line items into a spreadsheet, hunting down the number of your last invoice, and rewriting the same payment reminder email for the tenth time. AI isn't going to do your accounting for you, but it's genuinely good at three things: writing a clear quote from a three-sentence brief, turning that accepted quote into a complete invoice, and writing payment reminders. The rest — numbering, totals, VAT, archiving — gets sorted with a clean template and a free invoicing tool, not a €40-a-month subscription.
This guide compares four methods, from the fastest to the most automated, with the real costs, the honest limits, and the legal requirements you can't hand off to any language model. You can set the first one up this afternoon, in an hour, with what you already have.
What AI does well with your paperwork, and what it doesn't
AI is excellent at writing, structuring and chasing; it's bad at calculating, numbering and archiving.
Keep that sentence in mind — it prevents most beginner mistakes. A language model produces plausible text. It doesn't keep a register, it doesn't remember your previous invoice, and it can get a multiplication wrong while sounding completely sure of itself.
What AI does very well:
- turn a three-sentence brief into a detailed, line-by-line quote, with labels your client actually understands
- rewrite a vague service („website redesign") as priced deliverables („5-page mockup, build, 1-hour training session")
- draft the payment terms, the deposit, the number of revision rounds included
- write a firm reminder without being aggressive, in three escalating versions (day 7, day 15, day 30)
- read a confusing client email and pull out the information to pre-fill a quote
What you should hand to something other than a prompt:
- the chronological, gap-free numbering of your invoices
- calculating totals, VAT and rounding
- archiving for the legally required period
- exporting to your accountant
The mandatory details are on you
A business-to-business invoice has to carry a precise list of information: the identity and address of both parties, the SIREN company number, the issue date, a unique number, the description and quantity of the services, the unit price excluding tax, the applicable VAT rate, the payment due date and the late-payment penalties. The official list is published on the invoicing page of service-public.fr. Print it out and build it into your document template once and for all. After that, AI fills in the variables — never the legal details.
Second date to have on your radar: electronic invoicing is becoming mandatory in France. Every business will have to be able to receive electronic invoices from 1 September 2026. The obligation to issue them applies to large companies and mid-caps on the same date, then to SMEs and micro-businesses from 1 September 2027 (full timeline on impots.gouv.fr). In practice: a PDF knocked together on the side and emailed out won't cut it much longer — you'll need to go through an approved platform. So you may as well get into the habit now of separating the two roles: AI writes, an invoicing tool produces the official document.
Method 1: produce your quotes and invoices with Skilzy's AI Lab
Skilzy's AI Lab lets you write your quote and invoice prompts, test them straight away on real tools, and keep your templates — without stacking up subscriptions.
Skilzy is a French e-learning platform for learning and actually using AI. More than 15 programs are available (image, video and music creation, prompt writing, automation with n8n, AI-assisted coding), with a built-in AI Lab where the usage credits are included. For paperwork, three building blocks matter to you: the prompt-writing program, the n8n automation program, and Skilzy's AI Freelance program, which starts from the real tasks of a self-employed person: prospecting, quotes, invoicing, reminders.
The advantage over simply subscribing to a chatbot: you're not paying for three separate tools just to experiment, and you come out with reusable templates rather than a prompt improvised fresh for every client. Two certifications are state-recognised and eligible for funding: RS7439 (AI content marketing) and RS6792 (AI and sales).
What you build in an hour:
- Your price list, written down in black and white, service by service. It's the piece 80% of freelancers are missing, and it's the thing that stops AI from inventing prices.
- A quote prompt that takes a brief and outputs a structured table.
- An invoice prompt that picks up the accepted quote and converts it, without touching the amounts.
- Three reminders ready to copy, with a tone that ramps up gradually.
Here's the skeleton of the quote prompt, to adapt to your situation:
You are my admin assistant. From the client brief below, write a quote. Structure: one line of context, then a table of services (label, quantity, unit price excluding tax), then the total excluding tax, then the terms (30% deposit, valid for 30 days, 2 rounds of revisions included). Do not invent any price or any service: use only my price list. If something in the brief isn't on the list, flag it at the end of the quote instead of pricing it. Brief: [...] Price list: [...]
Read that „do not invent any price" instruction again. It's the most important line in the prompt. Without it, the model fills the gaps with rates that look credible but are wrong, and you end up committed to an amount you never decided on.
Training organisations have a dedicated B2B offer.
Method 2: ChatGPT, Claude or Gemini with a locked-down template
With a clean template document and a precise prompt, the free version of a chatbot is enough to write your quotes and invoices.
How to go about it:
- Create a single template file (word processor or spreadsheet) containing all the mandatory legal details, your logo and your terms. You never recreate it.
- In that file, leave clearly named empty fields: client, address, SIREN, service lines, totals.
- Ask the chatbot for the service lines and the text only, never the whole document. You copy, you paste.
- Calculate the totals in your spreadsheet, with formulas. Never in the chat.
- Export to PDF and keep a numbered copy.
The limits, so you don't discover them on a real invoice: a language model can get a total wrong, mix up pre-tax and tax-inclusive amounts, apply a random VAT rate, or shift a quantity. On a long conversation thread it can also reuse a previous client's name. Check every single figure, every time. If you're torn between tools, our comparison of Claude and ChatGPT after six months of daily use breaks down the differences on exactly this kind of writing task.
Cost: €0 on the free tier, around €20 to €23 a month for a paid plan if you need volume and file attachments.
Method 3: free invoicing tools, for the part AI shouldn't touch
For numbering, compliant PDFs, archiving and payment tracking, a free invoicing tool is more reliable than any prompt.
Several French services offer free invoicing for freelancers and small outfits: Henrri, Facture.net, Indy or Tiime on the free side; Abby or Freebe on the paid side, around €10 to €15 a month, with more tracking and payment management. These offers change often, so check the current terms before you commit.
These tools fix exactly the four weak spots of AI: they number without gaps, they calculate correctly, they archive, and they tell you which invoice is unpaid. On the other hand, they're mediocre at writing: you end up typing „Consulting services" across three lines yourself.
Hence the right reflex: AI writes the content, the tool issues the document. You generate your service lines with a prompt, paste them into the software, and let the software handle the maths and the numbering.
| Method | Cost | Setup time | What it covers |
|---|---|---|---|
| Skilzy AI Lab | Monthly subscription | about 1 hr | Writing, method, automation, fundable certification |
| Chatbot + locked-down template | €0 to €23/month | about 30 min | Writing only |
| Free invoicing tool | €0 | about 20 min | Numbering, PDF, archiving, payment tracking |
| n8n + AI | €0 self-hosted, about €24/month hosted | 1 to 3 days | The whole chain, from brief to reminder |
Method 4: the full automated chain with n8n
n8n connects your form, your AI and your invoicing tool so the quote, the invoice and the reminders go out without you touching anything.
n8n is a visual automation tool: you wire blocks together, no code required. The typical freelance scenario:
- A prospect fills in a form on your site (project type, budget, deadline).
- n8n sends the form content to an AI model along with your price list.
- The quote is generated, then you approve it from your phone. That human step is non-negotiable at the start.
- The quote goes out by email, with a signature link.
- Signature received, n8n creates the invoice in your invoicing tool and sends it.
- No payment by day 7? The first reminder goes out on its own. Then day 15, then day 30.
Budget a weekend to build this properly the first time, less if you start from an existing template. The real win is less about time saved than about the reminders: those are the ones you never get round to sending, and they're the ones that unblock your cash flow. To go deeper on the overall logic, read our practical guide to AI automation for entrepreneurs, and for the sending and follow-up side, our article on automating emails with AI.
One warning: never hook up an automation that sends financial documents without human approval until you've watched it run correctly twenty times in draft mode. A wrong quote sent automatically is a contractual commitment.
The takeaway
Start small: one clean document template, a written price list, two prompts. You're already getting two to three hours back a month and you stop putting off your reminders. Add a free invoicing tool for numbering and archiving, since mandatory electronic invoicing lands in 2026 and 2027. Full automation with n8n can come later, once the first two building blocks run without surprises. And whatever you do, keep the basic rule: AI writes, you check the numbers.
