The verdict in three sentences
An AI assistant connected to a law firm's internal knowledge base costs 15,000 to 50,000 EUR excluding VAT in Berlin in 2026, plus 100 to 800 EUR a month in large language model usage via API. It does not replace legal research: it finds in seconds the right clause template, the opinion drafted three years ago or the ruling annotated by a partner, with the source cited. The project is only defensible with EU hosting, matter-level access control and a vendor contract compatible with professional secrecy under the BRAO and section 203 of the German Criminal Code.
What the assistant does, and what it must not do
The technique is called RAG (retrieval-augmented generation): the firm's documents are indexed, the assistant retrieves relevant passages, then drafts an answer that cites each excerpt. No document is used to train the model.
| Use | Concrete example | Estimated gain per occurrence |
|---|---|---|
| Find a template | Non-compete clause for a sales executive under German law | 20 to 40 minutes |
| Reuse an opinion | Have we already handled termination of a commercial lease for renovation works? | 1 to 2 hours |
| Internal case law summary | Hearing notes and rulings annotated by partners | 30 to 90 minutes |
| First draft preparation | Brief outline built from similar matters | 1 to 3 hours |
| Associate onboarding | How does the firm draft its engagement letters? | Several days in year one |
What it must not do: give legal advice without a source, mix matters of opposing clients, or send files to a non-EU vendor without safeguards. Scoping sets these rules before the first line of code.
2026 budget by firm size
| Firm size | Indexed volume | Setup (EUR excl. VAT) | LLM API per month | EU hosting per month |
|---|---|---|---|---|
| 10 lawyers, one practice area | 20,000 documents | 15,000 to 22,000 | 100 to 250 EUR | 150 to 300 EUR |
| 20 lawyers, 2-3 practice areas | 60,000 documents | 22,000 to 35,000 | 250 to 500 EUR | 250 to 450 EUR |
| 40 lawyers, multi-office (Berlin, Hamburg) | 150,000 documents | 35,000 to 50,000 | 500 to 800 EUR | 400 to 700 EUR |
| Option: practice management software connector | Depends on vendor | 4,000 to 9,000 | Included | Included |
| Option: self-hosted model (no data with an AI vendor) | All volumes | 12,000 to 25,000 extra | 0 EUR | 900 to 2,500 EUR (GPU) |
The line that surprises most firms is document preparation: deduplication, OCR of scanned PDFs, metadata (client, practice area, date, author). It often represents 30 to 40 % of the initial budget. A firm that already runs a clean document management system saves several thousand euros.
GDPR and professional secrecy: the decision grid
| Requirement | Technical answer | Watch point |
|---|---|---|
| Data location | Servers in the EU (Germany or France) | Check the vendor's sub-processors |
| No reuse by the model | Enterprise API contract, no training, zero or 30-day max retention | Read enterprise terms, not consumer terms |
| Access separation | Permissions inherited from the DMS, filtered by team and matter | Ethical walls on conflicts of interest |
| Traceability | Log of queries and sources consulted | Define log retention |
| Data protection impact assessment | Drafted with the DPO before go-live | Mandatory for large-scale sensitive data |
| Secrecy obligations of vendors | Written confidentiality undertaking per section 43e BRAO | Required for every IT service provider |
The EU AI Act places this kind of internal assistant in the limited-risk category: the main obligation is transparency and user oversight. The real regulatory exposure remains the GDPR and professional rules.
Mini case study
Dr. Weber, managing partner of an 18-lawyer firm in Berlin (corporate and employment law), estimates that each lawyer spends about 5 hours a week searching internal documents or redoing what already exists. The firm invests 28,000 EUR excl. VAT in the assistant, plus 650 EUR a month (API and EU hosting).
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After three months, the measured gain is 3.5 hours per lawyer per week. At an internal cost of 90 EUR an hour (associates), over 45 weeks: 18 × 3.5 × 45 × 90 = 255,150 EUR of time freed per year. Even if only a quarter of that time becomes billable or reduces unbilled hours, about 64,000 EUR, the first-year investment (28,000 + 7,800 EUR) is covered in just over 6 months.
FAQ
How much does a knowledge base AI assistant cost for a Berlin law firm?
Between 15,000 and 50,000 EUR excl. VAT for setup, depending on the number of lawyers and documents, plus 250 to 1,500 EUR a month in API and hosting. A 20-lawyer firm usually sits around 25,000 to 35,000 EUR.
Do client documents go to OpenAI or Anthropic?
Only the excerpts needed for an answer pass through the API, under an enterprise contract without training and with European hosting where the vendor offers it. For zero exposure, a self-hosted model costs 12,000 to 25,000 EUR more.
Can the assistant invent case law?
The risk exists with a general chatbot. Here, every answer cites the internal documents used, and the assistant replies that no source was found rather than improvising. In our tests, more than 95 % of answers point to a verifiable source.
How long does deployment take?
8 to 12 weeks: scoping and DPIA (2 weeks), document preparation (3 to 4 weeks), development and testing with a pilot group of 4 to 6 lawyers.
Do we need an existing document management system?
No, but it speeds things up. Without one, indexing a file server is still possible; budget 3,000 to 6,000 EUR of extra preparation.
Let's scope your project. Tell us your firm size, practice areas and where your documents live: we price a GDPR-compliant assistant between 15,000 and 50,000 EUR excl. VAT, with a pilot in 8 weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
