The most important lesson I’ve learned in FP&A is simple, and yet it's often the one newcomers struggle with the most.
It’s to stop asking “is this right?” and start asking “what does this tell us?”
A lot of finance brains (especially accountants) are wired for a clean, rule-bound world. GAAP trains you to land on one right answer, reconcile the stray penny, and close the variance.
But FP&A lives in a different climate. Here the craft is getting comfortable with fuzzy logic: making explicit assumptions, stress-testing them, even breaking a model on purpose to see where it snaps. You treat the spreadsheet like a lab, not a ledger. Version A says price holds, Version B says conversion dips, Version C says hiring slips a quarter; which story best explains what you see?
The point isn’t to prove the model “correct.” It’s to use the model as a narrative tool that helps you answer those three questions we keep coming back to—what happened, why it happened, and what happens next—so the team can choose a path with eyes open.
Your job is to get comfortable taking the bowl of spaghetti (conflicting metrics, partial data, shifting targets) and knitting it into a tapestry that explains how and why the business is behaving the way it is. The tapestry won’t be perfect (especially early on). It’s going to have holes, and wonky stitching, and ugly patches, but in the end it’s going to be the map that you use to guide decisions.
FP&A in a nutshell
I’ve spent a lot of time around teams where GAAP thinking ruled the room. Of course I still love clean reconciliations. But planning lives in motion. The data may be late. The story may be messy. But you still need to make a call.
Here’s how that plays out.
One client (B2B Vertical SaaS, 50+ FTEs) called me after their marketing spend landed 28% above plan. Their accountant’s voice took over: check invoice dates, match POs, hunt the double count. They did clean a small miscode. Then we sat with their growth lead and looked at behavior, not just math. Paid social had spiked, and activation on trials from one creative set jumped. CAC in that slice actually improved. They kept their spend high for the next month and cut the weak channels. Pipeline picked up the following quarter. The ledger got fixed, sure, but the insight drove the win.
Another client, (DTC brand, ~150 FTEs), watched freight costs jump. The books said COGS, and someone had tucked a chunk into “other.” They sorted that. Old instincts would have stopped there. Instead we called ops. Found out they had switched to a faster carrier and shaved two days off delivery. CSAT ticked up. Returns dipped. Contribution margin was flat in month one, then improved as repeat orders rose. Turns out the movement in costs wasn’t a problem to reverse. It was a signal to price test the next region.
This is the hardest habit for finance folks I know, myself included. We love rules you can point at, but in planning, “correct” almost never exists, everything more quantum. You can’t pin down position and speed at the same time. You live in probabilities. If you sit with the numbers until every cell is pristine, the moment to act sails past. “Good enough to decide” is a very real thing, and finding it is a very valuable skill.
So when a variance shows up, I ask three things out loud:
What behavior does this reveal.
Is it a blip or a pattern.
If it continues, what choice would we make today.
And I don’t ask from a desk. FP&A lives in operations. In the sales standup. In a quick chat with the warehouse lead. In product’s weekly review. Go to the place where the number is made. Ask what changed. Then tie it into one short story others can act on.
Of course I still want accuracy. I still want tidy books.
But the point is insight.
The point is motion.
The point is turning a messy spreadsheet into a clear next step.