In the world of finance, we build intricate models and detailed projections. We spend countless hours ensuring the formulas are correct, the links are sound, and the presentation is clear. Yet the integrity of this entire structure often rests on a single, critical word that appears again and again in our supporting documents: “Assume.”
The financial model itself is a story about the future, and every assumption is a plot point. The danger is not that we make assumptions, we must, as we cannot know the future. The danger lies in how quickly we forget they are assumptions and begin to treat them as facts. A great financial leader doesn’t just audit the formulas; they apply intense pressure to the core assumptions that form the model’s foundation.
When a plan states, “We assume a 5% customer conversion rate,” the work has just begun. Why do we assume that? What is the historical evidence? Is that evidence from a different market condition that no longer applies? What are our competitors achieving? What happens to our entire business model if that rate is actually 2%, or even 3%? What is the most we could reasonably hope for, and what would have to be true to achieve it?
This kind of critical thought, this persistent questioning, is where a CFO creates the most value. It moves the conversation from a passive acceptance of a spreadsheet to an active engagement with business reality. It uncovers hidden risks and unexamined opportunities. By systematically challenging the assumptions that underpin our financial plans, we transform a simple forecast from a fragile statement of hope into a resilient and more credible strategic tool. The goal is not to eliminate assumptions, but to understand their profound impact and build a plan that is honest about its own uncertainties.
The quality of your strategy is determined by the quality of the assumptions you’re willing to challenge. My role as a Fractional CFO is to pressure-test the assumptions in your financial models. My role as an Executive Coach is to build a leadership culture where rigorous questioning is the norm. What’s the most dangerous assumption in your business right now? If you’d like a partner to help you uncover it, let’s talk.