You spend your Sunday evenings retyping line items into a spreadsheet, digging around for the number of your last invoice, and rewriting the same payment reminder email for the tenth time. AI isn't going to keep your books for you, but it's very good at three things: writing a clear quote from a three-sentence brief, turning that accepted quote into a complete invoice, and drafting payment reminders. The rest (numbering, totals, VAT, archiving) gets handled by a clean template and a free invoicing tool, not by a €40-a-month subscription.
This guide compares four methods, from the fastest to the most automated, with real costs, honest limitations, and the legal requirements you can't delegate to any language model. You can put the first one in place this afternoon, in about 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 ledger, it doesn't remember your previous invoice, and it can get a multiplication wrong while sounding perfectly confident.
What AI does very well:
- turn a three-sentence brief into a detailed quote, line by line, with labels your client actually understands
- rewrite a vague deliverable (‘website redesign') as priced line items (‘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 rambling client email and pull out the information needed to pre-fill a quote
What you should hand off to something other than a prompt:
- 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 include a precise list of information: names and addresses of both parties, SIREN number, issue date, unique invoice number, description and quantity of the services, unit price excluding tax, applicable VAT rate, payment due date and late-payment penalties. The official list is published on the service-public.fr invoicing page. 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 worth knowing: 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-sized firms on that same date, then to SMEs and micro-businesses from 1 September 2027 (detailed timeline on impots.gouv.fr). In practice: a PDF knocked together in a corner and sent by email won't cut it much longer — you'll have to go through an approved platform. So you may as well get into the habit right now of splitting the two roles: AI writes, an invoicing tool produces the official document.
Method 1: produce your quotes and invoices with the Skilzy AI Lab
The Skilzy AI Lab lets you write your quote and invoice prompts, test them immediately on real tools, and keep your templates, without stacking up subscriptions.
Skilzy is a French e-learning platform for learning and using AI. More than 15 programs are available (image, video and music generation, prompt writing, automation with n8n, AI-assisted coding), with a built-in AI Lab where usage credits are included. For paperwork, three building blocks matter to you: the prompt-writing program, the n8n automation program, and the Skilzy Freelance AI 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 don't pay for three separate tools just to experiment, and you come away 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 rate card, written down in black and white, service by service. It's the piece 80% of freelancers are missing, and it's what 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 escalates step by step.
Here's the skeleton of the quote prompt, to adapt as you see fit:
You are my business assistant. Using the client brief below, write a quote in English. Structure: one line of context, then a table of line items (label, quantity, unit price excluding tax), then the total excluding tax, then the terms (30% deposit, valid for 30 days, 2 revision rounds included). Do not invent any price or any service: use only my rate card. If something in the brief isn't on the rate card, flag it at the end of the quote instead of pricing it. Brief: [...] Rate card: [...]
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 credible but wrong rates, 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 one single template file (word processor or spreadsheet) containing all the mandatory details, your logo and your terms. You never recreate it.
- In that file, leave clearly named blank fields: client, address, SIREN, line items, totals.
- Ask the chatbot only for the line items and the text, never for 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 limitations, 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 figures, apply a random VAT rate or shift a quantity. It can also, in a long conversation thread, reuse a previous client's name. Check every figure, every time. If you're torn between tools, our comparison of Claude and ChatGPT after six months of daily use goes into the differences on this kind of writing task.
Cost: €0 on the free tier, roughly €20 to €23 per 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 per month, with more tracking and payment management. These offers change often, so check the current terms before committing.
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' yourself three lines in a row.
Hence the right instinct: AI writes the content, the tool issues the document. You generate your line items with a prompt, you paste them into the software, you let the software handle the maths and the numbering.
| Method | Cost | Setup time | What it covers |
|---|---|---|---|
| Skilzy AI Lab | Monthly subscription | about 1 h | 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 for the hosted version | 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 link blocks together, without writing code. The typical scenario for a freelancer:
- 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 rate card.
- 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 isn't so much the time saved as the reminders: those are the ones you never send, and they're the ones that unlock your cash flow. To dig into the bigger picture, 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 switch on an automation that sends financial documents without human approval until you've watched it run correctly twenty times in draft mode. A faulty quote sent automatically is a contractual commitment.
Key takeaways
Start small: one clean template document, a written rate card, two prompts. That alone gets you two to three hours back a month and stops you putting off your reminders. Add a free invoicing tool for numbering and archiving, since mandatory electronic invoicing is coming in 2026 and 2027. Full automation with n8n comes later, once the first two building blocks run without surprises. And whatever you do, stick to the basic rule: AI writes, you check the figures.
