25.06.2026
Local AI for Tax Firms: §203, Client Data and RAG
How tax firms can process documents, correspondence and internal knowledge with local AI.
#AI#TaxAdvisors#DataProtection
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§203 · DATEV · Client data
Local AI for tax advisers: receipts, client mail and firm knowledge inside your own network
Client data is subject to confidentiality under §57 StBerG and Section 203 StGB. We set up an AI platform inside the firm network, with approved data sources, roles and documented access paths.
Local processing with controllable data pathsConnect DATEV and firm software after an interface reviewNo billing per token or per user
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The situation
Confidentiality and AI in the tax firm: the starting point
Sorting, assigning and preparing client emails and incoming receipts takes time. When AI is used, the resulting data paths must be deliberately limited.
A DPA with a cloud provider does not define how data flows, source permissions and §203 are implemented technically. Service providers must also meet the requirements of §62a StBerG.
Client data combines financial, payroll and family data. A data leak affects professional duties and client trust.
Use cases
AI for tax advisers: use cases and what changes
These examples describe workflows. Data sources, permissions and professional review are defined for the concrete use case; review and approval stay with you.
Receipt recognition, classification and pre-accounting
Today
Incoming receipts are reviewed, named and assigned to the client.
With local AI
Receipts are recognised, classified and prepared with a posting suggestion. Review and posting stay with the firm.
Client email triage and pre-qualification (local)
Today
Client requests arrive mixed in the inbox and are pre-sorted one by one.
With local AI
Requests are summarised and pre-sorted by client, topic and urgency.
RAG research in BMF letters, case law and internal client history
Today
BMF letters, rulings and earlier advice to clients are searched by hand.
With local AI
Tax questions are answered from approved BMF letters, rulings and firm knowledge, each with a source reference.
Drafts for annual-report cover letters and client correspondence
Deadline and inquiry pre-check
Internal knowledge base on firm know-how and DATEV documentation
Our approach
Advise. Build. Operate. From one team.
Sovereign AI is a lifecycle, not a device purchase: advice, build and operations come from one team.
01
Advise & design
Workshop, sizing, data classification and §203 contract framework. We understand your stack, professional software and compliance requirements before we recommend.
02
Build & integrate
On-premise build on your hardware, RAG on your documents with access control, integration into your professional software. Plus the DPA and, on request, a written secrecy obligation under Section 203 StGB.
03
Operate & maintain
Updates, monitoring, model upgrades and RAG upkeep in ongoing operation. For the AI Cube, AI Cube Care runs with the device for the first twelve months and is cancellable monthly after that; handover to your team and knowledge transfer included.
Legal framework
Local AI for GDPR and Section 203 requirements
We configure and operate the local AI platform for the agreed GDPR and Section 203 scope, as an AI Cube or on your own infrastructure. This includes controlled data paths, limited permissions, documented maintenance, the appropriate DPA and, on request, written secrecy obligations for the people involved. Legal evaluation of the specific use remains with the controller and its advisers.
What §203 StGB prohibits
§203 StGB protects confidential information entrusted by clients, patients and other parties. The necessary involvement of contributing persons is permitted. What matters is that access is limited to what is necessary, the people involved are bound to secrecy and the complete data and maintenance path is controlled.
Why cloud AI is the problem
With public AI services, inputs and documents leave your own infrastructure. Whether a service is suitable in a specific case therefore depends not only on a DPA, but also on data flows, subprocessors, access permissions and the actual use.
Why local processing helps
On-premises inference, local vector search and internally operated interfaces keep technical processing in your controlled environment. This reduces external data paths and subprocessors and allows access to be limited precisely.
Managed service with a secrecy obligation
When we provide setup or operations as a contributing person, the people involved accept a written secrecy obligation and are instructed about the criminal consequences. Where personal data is involved, this is combined with a DPA, limited administrative rights and documented maintenance paths.
What we deliver for it
These technical and contractual building blocks form part of the agreed §203 scope:
AVV
Data-protection layer
Written secrecy obligation
Secrecy and instruction on criminal consequences
Maintenance and access concept
necessary rights, logging and controlled paths
This content is general information and not legal or tax advice. The specific implementation under §203 must be reviewed professionally on a case-by-case basis.
Blog & Tutorials
Related Tutorials & Guides
AI Cube
AI Cube as a local platform for firm knowledge
Staff receive a familiar AI chat with local models and dedicated knowledge areas. DATEV connections, document workflows and automated RAG pipelines are planned as a separate integration scope.
Delivered ready to use within 10 working days
AI Cube
from €6,490 excl. VAT one-time
Device, setup, briefing and shipping
from €349.90 excl. VAT / month
AI Cube Care · first year accompanied, then cancellable monthly
- Compact AI appliance on NVIDIA GB10 with 128 GB unified memory and 1 TB NVMe
- Open WebUI with knowledge bases, groups and roles
- A local language model, a fast model for short tasks and an embedding model
- Hardened system, firewall, HTTPS on the local network
- Remote maintenance through NetBird, logged and switchable
- Handover documentation, a 30-minute briefing and shipping within Germany
- Two-year manufacturer warranty
Expandable when required
RAG, data sources, integrations, secure connectivity and custom workflows are scoped separately.
Operable for the long term
AI Cube Care keeps the device running: a monthly maintenance window, tested model updates with a rollback path, round-the-clock monitoring, ticket support and warranty handling. The data processing agreement under Art. 28 GDPR comes with the order; for confidentiality professionals the written secrecy obligation is available on request under Section 203 (4) of the German Criminal Code, including instruction on the criminal consequences; on request remote access stays switched off by default.
Frequently asked questions about AI in tax firms
Answers to the most important questions
GDPR is one layer. For client data, confidentiality under §57 StBerG and Section 203 StGB and the service-provider requirements of §62a StBerG also apply. The Federal Chamber of Tax Advisers has published an FAQ catalogue on AI use. The firm assesses the specific use.
A connection can be implemented after reviewing the available interfaces and required data. It is a separate integration project and is not part of the standard delivery.
Local models process input within your own network. Any additional connections for updates, remote maintenance or connected services are defined and documented during setup.
Through local processing, clearly limited data sources, roles, audit logs and documented maintenance access.
We usually deliver the AI Cube fully preconfigured within two weeks after configuration approval. Professional-software connections, automated RAG pipelines or larger infrastructure are planned separately.
We document data flows, roles, technical safeguards and operational responsibility. Where personal data is processed, we conclude the appropriate DPA; on request, the people involved also accept a written secrecy obligation under Section 203 StGB, including instruction on the criminal consequences.
The AI Cube costs from €6,490 excl. VAT one-time for the 1 TB version, including setup, briefing and shipping. On top of that comes AI Cube Care at from €349.90 excl. VAT / month for patching, backup, monitoring and support; the first twelve months run with the device, cancellable monthly after that. Integrations and larger deployments are quoted separately.
Yes. We hand over with documentation and train your team. For the AI Cube, AI Cube Care runs for the first twelve months with the device and can be cancelled monthly after that; you can then take over operation yourselves. For other deployments, we agree maintenance, updates, model upgrades and RAG upkeep as needed.
Enquiry
Assess local AI for Tax Advisors
Describe the workflow and data that should be processed locally or in a controlled environment.
Contact
Let's Talk About Your Idea
Whether a specific IT challenge or just an idea - we look forward to the exchange. In a brief conversation, we'll evaluate together if and how your project fits with WZ-IT.
Arrange a callback
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