You spend your Sunday evenings retyping line items into a spreadsheet, hunting for the number of your last invoice, and rewriting the same payment reminder email for the tenth time. AI isn't going to do your bookkeeping 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 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 following up; 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 botch a multiplication while sounding perfectly confident about it.
What AI does very well:
- turn three sentences of brief into a detailed quote, line by line, with labels the client actually understands
- rephrase a vague service (“website redesign”) into priced deliverables (“5-page mockup, build, 1-hour training session”)
- draft 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 needed to pre-fill a quote
What you should hand 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 specific list of information: the name and address of both parties, company registration 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 invoicing page at 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 need to be able to receive electronic invoices by September 1, 2026. The obligation to issue them applies to large companies and mid-sized firms on that same date, then to SMEs and micro-businesses on September 1, 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 have to go through an approved platform. So you may as well start separating the two roles right now: 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 creation, prompt writing, automation with n8n, AI-assisted coding), with a built-in AI Lab where usage credits are included. For paperwork, three pieces 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, follow-ups.
The advantage over simply subscribing to a chatbot: you don't pay for three separate tools just to experiment, and you walk away with reusable templates instead of a prompt improvised fresh for every client. Two certifications are state-recognized 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 takes the accepted quote and converts it, without touching the amounts.
- Three reminder emails ready to copy, with a tone that escalates step by step.
Here's the skeleton of the quote prompt, to adapt as you like:
You are my business admin assistant. Using the client brief below, write a quote in English. Structure: one line of context, then a table of services (label, quantity, unit price excluding tax), then the subtotal 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 instruction again — “do not invent any price.” 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 committing to a figure you never decided on.
Training organizations 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 details, your logo and your terms. You never rebuild it.
- In that file, leave clearly labeled blank fields: client, address, registration number, line items, totals.
- Ask the chatbot only for the line items and the text, 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 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 amounts, 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 number, 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 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. 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 instinct: AI writes the content, the tool issues the document. You generate your line items with a prompt, paste them into the software, and let the software handle the math and the numbering.
| Method | Cost | Setup | What it covers |
|---|---|---|---|
| Skilzy AI Lab | Monthly subscription | about 1 hour | 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 that the quote, the invoice and the reminders go out without you lifting a finger.
n8n is a visual automation tool: you wire blocks together, no code required. 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 is less about time saved than about the reminders: those are the ones you never send, and they're the ones that unlock your cash flow. To go further on the overall logic, read our practical guide to automation with AI for entrepreneurs, and for the sending and tracking 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 faulty quote sent automatically is a contractual commitment.
Key takeaways
Start small: one clean document template, a written rate card, two prompts. You already claw back two to three hours a month and you stop putting off your payment 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 pieces run without surprises. And in every case, stick to the basic rule: AI writes, you check the numbers.
