The Most Expensive Lesson in Business Isn't in Any Textbook - it's Fixed Expenses

How Smart Founders Think About Fixed Expenses vs. Variable Costs — and Why Getting It Wrong Can Sink a Company

As a Fractional CFO, I've been in the room during some of the hardest conversations a founder will ever have.

Not the exciting hard conversations — the ones about raising a round, scaling a team, landing a major enterprise deal. I mean the other ones. The ones where a founder has to look their leadership team in the eye and tell them that the cost structure they built in good times is now threatening the entire business.

Layoffs. Office closures. Vendor contracts being unwound. Full-time roles being eliminated.

I've supported companies through restructurings, turnarounds, and near-death moments. And across all of those experiences, one pattern repeats itself with painful consistency:

Fixed expenses are easy to add. They are brutal — sometimes devastating — to remove.

This isn't a cautionary tale about bad operators. Most of the founders I've worked with are excellent. They're smart, mission-driven, and genuinely skilled at building. But somewhere in the excitement of growth, they made a series of individually reasonable decisions that collectively created a cost structure that left them with no room to maneuver when things got hard.

And in business, things always get hard.

This post is about how to think differently before that moment arrives.

What Fixed Expenses Actually Are — and Why They're So Dangerous

Most finance content explains fixed vs. variable costs in terms of accounting definitions. I want to explain it in terms of what it feels like to run a company.

Variable expenses are flexible. They scale with your business. When revenue grows, they grow. When revenue contracts, they can contract too. Think: contractor fees, commission-based compensation, usage-based software, project-based professional services. These expenses breathe with your business.

Fixed expenses don't care about your revenue. They show up every single month — same amount, no negotiation, no flexibility — whether you're having your best quarter or your worst. Think: full-time salaries, office leases, annual software subscriptions, retainer agreements. These are structural commitments.

The danger isn't the expense itself. It's the permanence.

When you hire a full-time employee, you're not just committing to a salary. You're committing to benefits, payroll taxes, management overhead, onboarding time, and — in the painful scenario where things don't work out — severance, legal risk, and the emotional and cultural cost of a layoff. The true fully-loaded cost of a $100K employee is often $140K-$160K or more. And once that commitment is made, it's incredibly difficult to unwind quickly without real damage.

When you sign a 3-year office lease, you're not just committing to a monthly payment. You're betting that your business, your headcount, and your model will remain stable enough to justify that space for 36 months. That's a long bet in a fast-moving environment.

The math of fixed expenses works beautifully when revenue is growing. Every new dollar of revenue has less overhead to cover. Margins expand. The business feels like it has momentum.

But the math works in reverse just as powerfully. When revenue declines — or even just grows slower than expected — fixed expenses don't compress. Your margin doesn't flex. And suddenly a 20% revenue miss becomes a 60% cash flow crisis.

That asymmetry is what makes fixed expense decisions so consequential.

Bullets Then Cannons: The Framework That Should Guide Every Growth Decision

Jim Collins and Morten Hansen introduced one of my favorite strategic frameworks in Great by Choice: Bullets then Cannons.

The concept is deceptively simple. The best companies — the ones that outperformed their peers by extraordinary margins over decades — didn't make big, bold, concentrated bets first. They fired bullets first: small, low-cost, low-risk experiments designed to validate whether something works before committing real resources.

Only once a bullet confirmed the target did they load the cannon and concentrate their resources behind it.

Most entrepreneurs do the opposite.

They fall in love with the vision. They get excited about the opportunity. They hire the team, sign the lease, build the infrastructure — and then go find out whether the thing actually works.

That's firing cannons before you've confirmed the target. And when you miss — and in business, you will miss sometimes — the cost isn't just the wasted capital. It's the fixed expense overhang that follows you for months or years after the miss.

I think about this framework constantly in my work with founder-led companies. Every significant growth investment deserves a bullet phase first.

Thinking about expanding to a new market? Don't hire a regional sales director and sign a new office lease. Find a way to test demand with your existing team and a contractor before you make the structural commitment.

Thinking about building a new product line? Don't staff up a full team. Validate the concept with a minimal version first.

Thinking about adding an executive to the leadership team? Consider a fractional or project-based engagement before converting to a full-time hire.

The goal isn't to be timid. The goal is to be strategic about when you fire the cannon — so that when you do, you've already confirmed you're aiming at the right target.

The AI Inflection Point: A New Answer to an Old Question

For decades, the default answer to "how do we get this done" was headcount.

Need financial analysis? Hire an analyst. Need tax research? Hire a tax associate or pay a specialist firm. Need to process a backlog of vendor contracts? Hire someone to read through them.

That equation is changing — fast. And founders who understand this shift have a meaningful structural advantage over those who don't.

Here's how AI has already changed the math in our own practice at Tee Up Advisors:

• Quick financial analysis that used to require a junior analyst spending half a day pulling data, building a model, and formatting a summary? Claude Code handles it in a fraction of the time. We can run scenario analyses, build projections, and stress-test assumptions faster than ever — without adding headcount to do it.

• Tax research that used to mean an expensive call with a specialist before we even knew what questions to ask? ChatGPT allows us to get educated quickly, frame the right questions, and arrive at that specialist conversation already oriented — which compresses billable hours and improves the quality of the advice we receive.

• Document review, vendor benchmarking, board prep, financial narrative building — AI is quietly eliminating entire categories of analytical work that founders previously had no choice but to hire for.

This doesn't mean every analytical function can be replaced. Senior judgment, strategic perspective, relationship management, and deep contextual knowledge still require experienced humans. But the supporting layer of analytical work — the research, the drafting, the synthesis — is increasingly being done faster and cheaper with the right AI tools.

For a founder thinking about their cost structure, this is a genuine strategic opportunity. Before you make your next fixed expense commitment, ask seriously: Is there an AI-enabled way to accomplish this that keeps the expense variable?

The One Thing AI Still Can't Do

I want to be honest here, because I think the AI conversation can get unrealistically euphoric.

Last week a client sent me a particularly charged email. Frustrated. Accusatory. The kind of message that makes your jaw tighten just reading it.

No AI is going to handle that for me. That moment requires a human being — with emotional regulation, relational awareness, empathy, and the wisdom to respond rather than react.

But here's what I did: I opened Claude, typed "act as my executive coach," and walked it through the full situation. What happened. What was said. What I was feeling. What outcome I was hoping for.

What came back was genuinely useful. A reframe on the client's likely underlying concern. A suggested approach to the response. A draft that was measured, professional, and oriented toward resolution rather than defense.

I still wrote the final email. I still made the judgment calls. I still carried the relationship.

But I got there faster and more clearly because I had a tool that could help me think — not just act.

That's the right mental model for AI in business. Not replacement. Not magic. But a genuinely powerful thinking partner and analytical accelerator that, when used well, allows you to operate at a higher level with a leaner structure.

A Framework for Every Founder

Here's how I think about this in practice. Before any significant expense commitment, I ask three questions:

1. Is this a bullet or a cannon? Can I find a lower-cost, lower-commitment way to validate this before I make a structural commitment? What would a 90-day test version of this look like?

2. Is there an AI-enabled alternative? Before I add headcount or a fixed retainer, is there a way to accomplish this with existing tools and AI augmentation? What would I need to build or learn to make that work?

3. What does this look like in a downside scenario? If revenue is 20% below plan six months from now, how does this expense feel? Is it still justified? Can I exit it if I need to? What's the true cost of unwinding it?

These aren't meant to make you slow or timid. They're meant to make your fixed expense additions intentional — so that when you do make them, you've thought through what you're actually committing to.

The founders who navigate hard transitions with the most resilience aren't the ones who never made bold bets. They're the ones who kept their cost structure lean and variable long enough to survive the inevitable rough patches — and flexible enough to pivot when the market required it.

What This Means for Your Business Right Now

If you're a founder reading this, I want to leave you with one honest question:

If your revenue dropped 25% tomorrow, how long could you sustain your current cost structure without making painful cuts?

If the answer makes you uncomfortable — that's worth paying attention to. Not as cause for alarm, but as a signal that it's worth doing the work now, before you're forced to.

At Tee Up Advisors, this is one of the first conversations we have with every new client. Not because we're pessimists — we're not. We work with founders who are building extraordinary companies. But we believe that sustainable, lasting growth is built on a financial foundation that can absorb volatility without breaking.

Fixed expenses aren't the enemy. Uninformed fixed expense growth is.

Fire your bullets first. Confirm the target. Then load the cannon — and make it count. 🎯

Ready to take a hard look at your cost structure? Let's talk!

Bob Wang is the founder of Tee Up Advisors, a strategic CFO firm serving founder-led companies from $3M to $20M in revenue. He holds an MBA from UC Berkeley, and has served as CFO of a VC-backed SaaS company sold for $100M. Tee Up Advisors helps founders build enduringly profitable companies that scale, exit successfully, and create generational wealth.