"The AI for your tax return"
SteuerGPT is an AI-powered chatbot for tax-related questions within WISO Steuer. Users can ask questions in everyday language while completing their tax return; the AI explains matters, guides them to the appropriate input forms, suggests missing information, and helps them understand their tax assessment notice.
TaxGPT
SteuerGPT: Your digital advisor - The AI for your tax return
Location: Germany ⓘ Buhl Data Service GmbH, Am Siebertsweiher 3/5, 57290 Neunkirchen (Siegerland), Germany.
Trial version: Complete testing before submission.
Note: No direct prices stated, as only model names and functions are documented here. Other Single purchase: One-time license for one tax year with SteuerGPT and filing option.
Optional additional services: ProfiCheck and buhl:Berater are offered separately via Buhl Steuerberatungsgesellschaft mbH; Buhl Data Service itself points out that it is neither obligated nor authorized to provide tax law assistance.
Target audience
SteuerGPT is primarily aimed at people who prepare their tax return themselves using WISO Steuer and need understandable help along the way. The tool is especially relevant for employees, retirees, families, students, career starters, self-employed individuals, and freelancers who want to clarify tax-related questions directly in the context of their return. For companies, SteuerGPT is only indirectly suitable, for example for owners or self-employed managing directors, but not as a full-fledged enterprise tax platform. According to the provider, WISO Steuer itself is positioned for beginners and professionals, employees, self-employed individuals, and retirees.
Outstanding features
SteuerGPT stands out because the AI does not operate as a general chatbot, but as an integrated tax assistant within WISO Steuer. The tool answers questions in everyday language, shows where information should be entered in the tax return, makes suggestions for missing information, and helps users understand the tax assessment notice. According to WISO, the answers are based on proven WISO tax content, are continuously reviewed, and are intended to make technical tax language easier to understand.
Main use cases
The main areas of use are answering tax questions, navigating input forms, optimizing the tax return, checking for potentially missing information, explaining tax terms, and translating explanations in the tax assessment notice into everyday language. In addition, WISO Steuer supports the entire tax return process through related features such as tax retrieval, tax box, receipt recognition, electronic ELSTER submission, and assessment notice review.
Usage & notes
It is used directly in WISO Steuer: users type their question into a chat window, SteuerGPT responds immediately and, if necessary, refers them to the appropriate sections of the tax return. It should be noted that, according to the provider, AI-generated answers may contain inaccuracies and do not replace advice from tax experts. From a data protection perspective, it is relevant that SteuerGPT can also process sensitive personal data; according to Buhl, this is done on the basis of consent, via Taxy.io as a data processor, and Microsoft Azure in German data centers.
| Target audience | Assessment |
|---|---|
| Private individuals | Yes – particularly suitable for employees, students, retirees, couples, and people with a standard income tax return. |
| Self-employed / freelancers | Yes – suitable when WISO Steuer is used for EÜR, business expenses, and tax returns; SteuerGPT helps with comprehension and input questions. |
| SMEs | Partly – more suitable for sole proprietors, small self-employed businesses, and private tax cases, not as a full-fledged corporate tax or accounting system. |
| Large enterprises | Rather no – SteuerGPT is geared toward individual tax returns within WISO Steuer, not enterprise tax compliance. |
| Developers / technical teams | No – no standalone API, no model access, no LLM deployment. |
| Privacy-sensitive private users | Yes, comparatively well suited – German provider, servers in Germany, and according to the provider no use of personal data by SteuerGPT. |
| Tax advisors / firms | Partly – helpful as an end-user tool, but not a firm workflow system and not a professional tax advisory platform. |
Hosting & Data
1) On-prem / local hosting
Meaning: The company operates the solution on its own hardware or within its own infrastructure. In the strictest sense, not only the application runs locally, but ideally the model as well.
2) Private cloud / data center
Meaning: The solution runs in a dedicated or more clearly separated cloud environment, often with a hosting provider or hyperscaler, but in a German data center or in a particularly controlled environment.
3) EU SaaS / managed
Meaning: The provider operates the solution itself as a service. The company uses the tool as a ready-made cloud service, ideally with EU data residency.
4) Hybrid
Meaning: One part of the processing remains internal / local / in a private cloud, while another part runs in an external cloud or EU SaaS.
5) AVV / DPA
Meaning: This is the data processing agreement or Data Processing Addendum. It governs that the provider processes personal data on behalf of the customer and is bound by the customer's instructions.
6) No training
Meaning: The provider does not use your prompts, uploads, attachments, chat histories, or outputs for training or improving the general model — ideally excluded by contract.
7) Open-source / transparency path
Meaning: There is a path toward greater technical transparency and sovereignty, for example through:
- open models
- documented components
- self-hostable parts
- traceable architecture
- export / switching options
| On-prem / local hosting | ❓ |
| Private cloud / data center | ⚠️ |
| EU SaaS / Managed | ✅ |
| Hybrid | ⚠️ |
| DPA / AVV | ⚠️ |
| No training on customer data | ❓ |
| Open source / transparency path | ❓ |
On-prem / local hosting: indirect / not available
No on-premise, local, or self-hostable deployment of SteuerGPT was indicated on the website.
Private cloud / data center: partial
The website mentions German data centers and Buhl's own servers in Germany. However, a dedicated or tenant-separated private cloud architecture for customers is not indicated on the website.
EU SaaS / managed: covered
SteuerGPT is directly integrated into WISO Steuer and offered as a ready-made service. German data centers are mentioned for SteuerGPT; it is also stated that the applications do not leave the European legal area.
Hybrid: partial
The website suggests that data is stored on Buhl servers in Germany, while processing for AI functions is carried out by OpenAI Ireland as a processor. However, an explicit hybrid architecture for SteuerGPT is not described in detail.
DPA / Data Processing Agreement: partial
The terms and conditions state that, when personal data is processed on behalf of a customer, a data processing agreement is concluded in advance. In addition, the discoverable privacy policy for AI functions mentions a DPA with OpenAI including SCCs. A directly linked, SteuerGPT-specific DPA/Data Processing Agreement for customers to conclude was not indicated on the website.
No training: unclear
An explicit exclusion stating that prompts, uploads, chat histories, or outputs from SteuerGPT are not used to train general models was not indicated on the website. An opt-out option from AI training was also not indicated.
Open source / transparency path: unclear
Open-source components, open models, self-hostable parts, or a documented transparency path were not indicated on the website.
Data processing
The pages found suggest processing within the EU/EEA area with a strong Germany focus: SteuerGPT mentions German data centers and no departure from the European legal area; WISO Steuer mentions Buhl's own servers in Germany. In addition, an AI-related privacy passage can be found on the website in which OpenAI Ireland is named as a processor with DPA and SCCs. A complete, SteuerGPT-specific description of subprocessors, training use, and technical architecture was not indicated on the website.
Conclusion
For users in the European area, the data protection and hosting documentation is overall usable, but not complete. The best-documented status is EU-/Germany-centered SaaS with German data centers or Buhl servers in Germany and a DPA/SCC structure for AI functions. Due to missing, clearly SteuerGPT-specific information on subprocessors, training exclusion, certifications, and alternative hosting models, the overall GDPR assessment is conditional.
Sources
| On-prem / local hosting | ❓ |
| Private cloud / data center | ⚠️ |
| EU SaaS / Managed | ✅ |
| Hybrid | ⚠️ |
| DPA / AVV | ⚠️ |
| No training on customer data | ❓ |
| Open source / transparency path | ❓ |
On-prem / local hosting: indirect / not available
No on-premise, local, or self-hostable deployment of SteuerGPT was indicated on the website.
Private cloud / data center: partial
The website mentions German data centers and Buhl's own servers in Germany. However, a dedicated or tenant-separated private cloud architecture for customers is not indicated on the website.
EU SaaS / managed: covered
SteuerGPT is directly integrated into WISO Steuer and offered as a ready-made service. German data centers are mentioned for SteuerGPT; it is also stated that the applications do not leave the European legal area.
Hybrid: partial
The website suggests that data is stored on Buhl servers in Germany, while processing for AI functions is carried out by OpenAI Ireland as a processor. However, an explicit hybrid architecture for SteuerGPT is not described in detail.
DPA / Data Processing Agreement: partial
The terms and conditions state that, when personal data is processed on behalf of a customer, a data processing agreement is concluded in advance. In addition, the discoverable privacy policy for AI functions mentions a DPA with OpenAI including SCCs. A directly linked, SteuerGPT-specific DPA/Data Processing Agreement for customers to conclude was not indicated on the website.
No training: unclear
An explicit exclusion stating that prompts, uploads, chat histories, or outputs from SteuerGPT are not used to train general models was not indicated on the website. An opt-out option from AI training was also not indicated.
Open source / transparency path: unclear
Open-source components, open models, self-hostable parts, or a documented transparency path were not indicated on the website.
Data processing
The pages found suggest processing within the EU/EEA area with a strong Germany focus: SteuerGPT mentions German data centers and no departure from the European legal area; WISO Steuer mentions Buhl's own servers in Germany. In addition, an AI-related privacy passage can be found on the website in which OpenAI Ireland is named as a processor with DPA and SCCs. A complete, SteuerGPT-specific description of subprocessors, training use, and technical architecture was not indicated on the website.
Conclusion
For users in the European area, the data protection and hosting documentation is overall usable, but not complete. The best-documented status is EU-/Germany-centered SaaS with German data centers or Buhl servers in Germany and a DPA/SCC structure for AI functions. Due to missing, clearly SteuerGPT-specific information on subprocessors, training exclusion, certifications, and alternative hosting models, the overall GDPR assessment is conditional.
Sources
Strengths & weaknesses at a glance
| Strengths | Weaknesses |
|---|---|
| - Deeply integrated into WISO Steuer, no separate tool required. | - Not available as a standalone SaaS/API tool. |
| - Tax-specific specialization instead of a general chatbot. | - According to the provider, AI responses may contain inaccuracies or errors and do not replace advice from tax experts. |
| - Guides users to the appropriate sections in the tax return. | - Use is tied to WISO Steuer. |
| - Can be used free of charge within WISO Steuer. | - According to the FAQ, WISO Steuer is not suitable for persons with limited tax liability. |
| - According to the privacy notice, data processing for SteuerGPT takes place via Taxy.io and Microsoft Azure in German data centers. | - There is no publicly documented on-premise or open-source operation for SteuerGPT. |
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GDPR-compliant usage possible?
The website provides several strong data protection and hosting indications for use within the EU/EEA: according to the product page, SteuerGPT is operated in German data centers and does not leave the European legal area; the WISO tax page also mentions the company's own Buhl servers in Germany. At the same time, the privacy policy for AI functions available on the website refers to a transfer to OpenAI Ireland Ltd as a processor, including a DPA and standard contractual clauses. However, for SteuerGPT itself, no separate, fully elaborated section on subprocessors, data flow, training exclusion, or EU data residency at the component level can be found on the located pages. This makes GDPR-compliant use within the EU/EEA plausible, but only on the condition that the documented statements regarding processing by OpenAI Ireland and the European hosting information actually apply to SteuerGPT in this form.
Positive
Positively documented are a privacy policy on the Buhl website, statements about German data centers or the company's own Buhl servers in Germany, as well as a DPA/SCC statement for AI functions with OpenAI Ireland as a processor. In addition, the SteuerGPT page emphasizes that no personal data is used or analyzed and that the applications do not leave the European legal area.
Negative
Negative is that no separate, clearly SteuerGPT-specific section is provided on the located SteuerGPT pages regarding subprocessors, training use of the content, opt-out from AI training, certifications, on-premise/self-hosting, or open-source components. An explicit list of subprocessors named specifically for SteuerGPT was also not provided on the website.
Server location
The website states for SteuerGPT that the applications are operated in German data centers and do not leave the European legal area. The WISO tax page also states that the data remains on the company's own Buhl servers in Germany. Beyond that, no precise naming of individual data center locations or a detailed description of EU data residency at the component level is provided on the website.
