From 9 Hours to 2: Inside German Tax Advisory Network HSP GRUPPE's Real ChatGPT Transformation

Hey everyone, it's Shiichan! Today I found a really compelling story about how tax and accounting professionals are working with ChatGPT, so let's get into it.

OpenAI News openai.com

What was announced?

OpenAI News shared a case study about HSP GRUPPE, a German network of legally independent tax advisory, auditing, and law firms, rebuilding its operating model around ChatGPT Enterprise. HSP GRUPPE has invested in standardizing and digitizing its firm processes for more than two decades. ChatGPT Enterprise is now embedded across tax advisory, legal research, client communication, financial analysis, and knowledge sharing throughout the firm network.

Why it matters

A common pattern when companies adopt generative AI is using it to write emails faster or summarize documents, small conveniences for individuals. HSP GRUPPE's leadership asked a bigger question instead: what happens when AI becomes part of the operating model of a professional services firm itself?

Here is how CEO Carsten Schulz put it:

Technology is moving faster than organizations can transform. Our challenge wasn't introducing AI, it was helping the organization absorb it.

That's why HSP GRUPPE treated AI adoption as organizational transformation rather than a software rollout, focusing on adoption, governance, and continuous learning. Monthly AI forums gave employees a place to share practical use cases with each other. Client-related information is governed by HSP's internal data protection, confidentiality, and governance rules, and professional review and final responsibility always remain with the relevant tax, legal, or accounting professional.

What changes

Use cases that spread organically across the firm network eventually got standardized into shared Agents. Two stand out:

• AI Client Communication: a shared Agent that supports first drafts, structure, clarity, and a consistent, client-oriented tone
• Booking Assistant SKR03 & SKR04: an Agent that supports classifying bookkeeping entries under Germany's SKR03 and SKR04 chart-of-accounts standards

In both cases, the final professional decision stays with the employee, which means even people who aren't AI experts can tap into best practices.

Individual professionals have found concrete uses of their own:

• Managing Partner Frank Heibel uses ChatGPT as a technical sparring partner for working through complex tax questions. "ChatGPT has become a genuine sparring partner. It completely changes the level at which you can work," he says
• Partner Magdalene Posnak cut the time to evaluate multiple real estate investments from nine hours to around two, freeing up time for client advisory
• Managing Director Marco Sell uses AI-powered dashboards to explore financial scenarios together with clients during meetings
• Lawyer and tax advisor Jan-Henrik Leifelt uses ChatGPT to strengthen, not replace, his professional judgment

Dive Deep

The announcement shares usage data from a six-month period, February 1 to July 14, 2026. Note that these figures cover the ChatGPT Enterprise workspace HSP GRUPPE shares with partner firm Kanzleipakt, spanning 81 organizational groups, not HSP GRUPPE alone.

• 84% weekly active usage, with 755 weekly active users and 913 unique users
• Over 500,000 messages exchanged with ChatGPT during the period
• 98.6% of surveyed employees reported higher productivity, and 84.6% reported improved quality of work
• 95.9% reported weekly time savings, with 63.5% saving at least two hours per week and 25.7% saving at least five hours
• 79.7% reported better client service and 78.1% reported higher job satisfaction
• A deliberately conservative internal scenario estimates about 40,000 hours of additional annual capacity, roughly 28,000 hours for billable specialist work and 12,000 hours for administration and client service. At conservative hourly rates, that translates to a theoretical annual revenue potential of about €3.8 million, which the report is careful to note is a capacity scenario, not realized or guaranteed revenue

HSP GRUPPE is already moving into its next phase, piloting ChatGPT Work with a small group of developers and administrators to explore how agentic AI can safely automate complex workflows. Schulz points to year-end accounting as an example: today, accountants often discover missing information only months after bookkeeping wraps up, and he wants ChatGPT Work to continuously review bookkeeping through the year and proactively request missing documents from clients. The firm has already identified 88 automation opportunities, but Schulz says that's still thinking too small: "The real question isn't how we automate today's processes. It's how we redesign them."

Looking ahead, HSP GRUPPE plans to team up with Kanzleipakt to build a joint DATEV-centric AI, process, and development team that turns successful, scattered experiments into documented, reusable workflows.

Wrap-up

• OpenAI News shared how HSP GRUPPE, a German tax advisory and audit network, is rebuilding its operating model around ChatGPT Enterprise
• Grassroots use cases were standardized into shared Agents like AI Client Communication and Booking Assistant SKR03 & SKR04
• Individual results include cutting real estate investment evaluation from nine hours to two
• 84% weekly active usage, 95.9% reporting time savings, and a conservative estimate of about 40,000 hours of added annual capacity (figures for the whole shared workspace with its partner firm)
• Next up is a ChatGPT Work pilot, moving from task support toward automating entire workflows
• Worth a read for leadership and DX teams at professional services firms balancing organization-wide AI adoption with governance