AI Tax Firm: What the Future of the Billion-Euro Tax Advisory Market Looks Like

Lukas Zörner co-built Penta into one of Germany's best-known fintech brands and led the Germany business after its acquisition by Qonto. Instead of resting on that success, he's now building something that sounds decidedly unglamorous at first: a tax advisory firm. But not a traditional one — one built from the ground up around its own tech stack. His company Integral just closed a Series A of 18 million euros, co-led by Mosaic Ventures and LinkedIn founder Reid Hoffman. On the podcast, Zörner explains why he believes tax advisory is facing a fundamental shift — and why he considers himself only at "F or G" on the journey from A to Z.

Why AI-Native Services Work Now

The starting point for Zörner's thesis is simple: "Companies don't want to buy software. What they actually want is for their problems to be solved." Classic SaaS providers for tax firms sell tools — Integral sells the outcome. The firm handles bookkeeping directly, but with a stack designed to automate as much as possible.

The core claim behind this is radical: "From a first-principles perspective, there's no reason manual bookkeeping should still exist in ten years." And that's exactly what's shaking up the industry's traditional business model — the hourly billing model. If a machine can complete a booking entry in three seconds, billing by time becomes absurd: "The machine books it within three seconds. Why should I pay the equivalent of an hour for that?"

Entering the industry as an outsider was still no easy feat. Licensing questions, data access, and building both the firm and the technology in parallel had to be solved simultaneously — a dual buildout that costs time and capital, but which Zörner sees as the only way to truly rethink the space instead of merely digitizing existing processes.

Product Builders Instead of Product Managers

Organizationally, Integral takes an unusual approach: there are no classic product managers. Instead, the tax experts themselves build the workflows — as "product builders." The idea: whoever understands the domain problem best should also build the solution, rather than passing requirements through multiple layers.

How seriously this is meant is illustrated by an anecdote from the podcast: when the CTO saw a feature built by a colleague with no coding background, his comment was: "You didn't vibe-code that, you actually coded that." A compliment that shows how high the quality bar remains despite fast iteration.

This balancing act is captured in an internal house rule: "Thoroughness before speed, but speed doesn't exclude thoroughness." The goal isn't a feature factory churning out as many functions as possible, but well-thought-out solutions that still ship fast.

A Market That Needs No Slide

The German tax advisory market is estimated at 35 to 45 billion euros per year. A market of that size hardly needs justification in an investor deck — and Zörner puts it with corresponding confidence: "There's one slide that's not in our deck, and that's market size." The scale is obvious; the real challenge lies elsewhere — actually capturing that market.

Even with fresh capital in hand, Zörner sees his company as still only at the beginning of a long road: "We've now reached an F, or maybe a G" — on a scale from A to Z. From his perspective, the Series A isn't a milestone but simply the prerequisite for really getting started.

When it comes to deploying capital, he thinks in terms of return on investment rather than budget maximization: "I'd be willing to spend ten times as much if the return on investment is there." The decisive question always remains: "What did you actually deliver?" — a principle he also applies to the use of AI tokens, whose deployment must be measured against actual output, not compute for its own sake.

Hiring With Radical Honesty

Team building at Integral also follows its own logic. Performance reviews happen every six weeks, based on a 4C framework — significantly more frequent than at most companies. On the topic of junior hiring, Zörner explicitly disagrees with his co-founder Fabian, though the podcast doesn't go into the details of the exact disagreement — a sign that differing opinions are openly debated even within the founding team.

In the hiring process, Zörner favors maximum transparency over sugar-coating: "Now we're crystal clear and say: this is what it takes" — making it plain that classic 40-hour work weeks aren't what's expected at Integral.

In the end, he sums up his motivation in a simple formula that also serves as a stress test for his own business model: "Walk down any street and strike out all the SMEs — that street is dead." Small and medium-sized businesses are the backbone of the German economy — and that, Zörner is convinced, is exactly why it's worth rebuilding their tax advisory from the ground up.