· Saul Mateos · CFO Career · 4 min read
How to Push Back as a CFO: Prudent, Not Lazy
How to push back as a CFO: the conversation that taught me the difference between a lazy no and a prudent no, and the four questions I ask now.
“You didn’t even think about the possibilities.” A partner said that to me once. Early in my career. After I’d shot down her idea in about 30 seconds. She was right. I was being lazy, not prudent. That conversation taught me how to push back as a CFO.
The Setup
The scenario was simple. She wanted to expand into a new market. The numbers didn’t work on first pass. ROI looked negative. Payback period too long.
So I said no. Fast. Confident. “The numbers don’t support it.”
She pushed back: “Did you model different scenarios? What if customer acquisition costs came down in year two? What if we bundled with existing products?”
I hadn’t. I’d run the base case, seen a negative return, and moved on.
That’s not financial prudence. That’s intellectual laziness wearing a CFO costume.
The Difference Between Prudent and Lazy
Here’s what I learned:
Lazy no: Run the base case. See a negative result. Say no. Move on.
Prudent no: Model multiple scenarios. Stress test assumptions. Identify what would need to be true for this to work. Explain why those conditions seem unlikely. Then say no.
The outcome might be the same. But the process matters.
A lazy no shuts down the conversation. A prudent no opens it up.
When you say “The numbers don’t work,” you’re ending the discussion.
When you say “The numbers would work if X, Y, and Z happened. Here’s why I think those are unlikely,” you’re inviting dialogue.
That dialogue often surfaces information you didn’t have.
How to Push Back as a CFO: The Framework I Use Now
Before I push back on any significant proposal, I ask myself four questions:
1. Did I actually explore the possibilities?
Not just the base case. The upside case. The downside case. The “what would need to be true” case.
If I only ran one scenario, I haven’t done my job.
2. What assumptions am I making?
Every no is built on assumptions. “CAC will stay elevated.” “Market adoption will be slow.” “Execution risk is high.”
Are those assumptions explicit? Have I tested them?
3. What would change my mind?
This is the key question. If nothing could change my mind, I’m not being analytical. I’m being stubborn.
Identify the conditions that would flip your answer. Then evaluate whether those conditions are plausible.
4. Can I explain my reasoning in two sentences?
If I can’t articulate why I’m saying no in two clear sentences, I probably don’t understand my own logic well enough.
“I’m saying no because [key assumption] and [supporting data]. If [condition], I’d reconsider.”
That’s it. That’s the format.
The Conversation I Have Now
Here’s how my budget pushback conversations go now:
Them: “We want to invest $500K in expanding into Market X.”
Old me: “The ROI is negative. No.”
New me: “I ran three scenarios. Base case shows negative ROI. But if CAC comes down 30% by Q3 (which happened in our last market entry), the payback period drops to 18 months. Here’s my concern: Market X has stronger incumbent competition. I think CAC is more likely to stay elevated than decline. Can you walk me through why you believe differently?”
Same analytical rigor. Different conversation.
The outcome? Sometimes I still say no. But now they understand why. And sometimes they surface information that changes my view.
That’s the job.
The Both/And Truth
I’m the CFO. My job is protecting the company from bad investments.
I also had to learn when to say no and when to say “show me more.”
Both are required.
Push back too fast, and you kill good ideas that could have worked.
Push back too slow, and you fund bad ideas that never should have started.
The balance isn’t a formula. It’s a practice.
Every conversation teaches you something about where the line should be.
The Last Proposal You Rejected
Think about the last proposal you rejected.
Could you articulate:
- What scenarios you actually modeled?
- What assumptions drove your conclusion?
- What would change your mind?
If you can’t answer all three, you might have been lazy, not prudent.
That’s not a failure. It’s a calibration.
Try again on the next one.