How HSP GRUPPE builds AI capabilities for tax advisory

What happened

The usage figures in this story refer to the shared ChatGPT Enterprise workspace used by HSP GRUPPE and Kanzleipakt, covering 81 organizational groups. HSP GRUPPE itself is a network of legally independent tax advisory, auditing, and law firms. For more than two decades, HSP GRUPPE⁠(opens in a new window) has consistently invested in digitizing and standardizing professional firm processes.

Together, these kinds of shared Agents reduce repetitive work while making best practices available to every employee—not just AI experts. Professionals then build on those foundations in their own work. Managing Partner Frank Heibel uses ChatGPT as a technical sparring partner to work through complex tax questions and refine client communications. “ChatGPT has become a genuine sparring partner. ” he says.

Partner Magdalene Posnak reduced the time required to evaluate multiple real estate investments from nine hours to around two, allowing her to spend more time advising clients. Managing Director Marco Sell uses AI-powered dashboards to help clients explore financial scenarios together during meetings, while lawyer and tax advisor Jan-Henrik Leifelt uses ChatGPT to strengthen—not replace—his professional judgment.

The common thread is simple: less time spent preparing information, and more time spent applying expertise. —Magdalene Posnak, Partner, HSP GRUPPE HSP is already preparing for the next phase of its AI journey with ChatGPT Work. Just weeks after gaining access, the organization began piloting the platform with a small group of developers and administrators before expanding across the wider workspace.

The goal is to understand how agentic AI can safely automate complex workflows while balancing governance, quality, and cost before broader rollout. For HSP, the economic benefit is not about reducing headcount. The firms in the network are already operating at capacity and managing substantial backlogs. Time saved with ChatGPT can therefore be redirected toward additional client work, shorter turnaround times, more advisory capacity, and stronger client service.

For Schulz, the opportunity isn’t simply helping people complete existing tasks more quickly. It’s redesigning the workflow itself. He points to year-end accounting as an example. Today, accountants often discover missing information only when they begin preparing annual accounts months after bookkeeping has been completed.

Why it matters

Long before generative AI, the firm network standardized processes, embedded quality management, and fostered a culture of continuous improvement across the network. When ChatGPT emerged, HSP saw more than another productivity tool. It saw an opportunity to rethink how professional work itself could evolve.

Rather than asking how AI could help employees write faster emails or summarize documents, leadership asked a broader question: What happens when AI becomes part of the operating model of a professional services firm? That vision led HSP to embed ChatGPT Enterprise into tax advisory, legal research, client communication, financial analysis, and knowledge sharing across the firm network.

—Carsten Schulz, CEO, HSP GRUPPE HSP approached AI as an organizational transformation rather than a software rollout. The organization introduced ChatGPT Enterprise with a strong focus on adoption, governance, and continuous learning. Monthly AI forums gave employees a place to share practical use cases and learn from one another.

ChatGPT Enterprise’s security features provide an important technical foundation, while the use of client-related information is governed by HSP’s internal data protection, confidentiality, and governance requirements. Professional review and final responsibility always remain with the relevant tax, legal, or accounting professional. The goal wasn’t simply to encourage experimentation. It was to build an organizational capability that could scale.

As Carsten Schulz puts it: “People ask me what my favorite AI feature is. I never answer that question. Individual features don’t matter. ” Across the firm network, professionals quickly found new ways to apply AI to their daily work, while the organization also began standardizing successful use cases into custom Agents.

One example is AI Client Communication, a shared Agent that supports first drafts, structure, clarity, and a more consistent, client-oriented tone. Professional review and final responsibility remain with the relevant tax, legal or accounting specialist. Another is the Booking Assistant SKR03 & SKR04, which supports the preparation and classification of specific booking questions. The final professional decision remains with the employee.

What to watch

HSP is exploring how ChatGPT Work could continuously review bookkeeping, identify missing information throughout the year, and proactively request documents from clients—so that much of the preparation has already happened before an accountant even opens the file. That shift—from AI assisting people to AI orchestrating work across entire processes—represents the next stage of HSP’s transformation. HSP believes its biggest AI gains still lie ahead.