Scenario / What-If Planner: Stress-Test the Plan Before You Bet On It

The problem this kills

Every important decision — hire the team or hold, raise prices or not, push growth or protect runway — comes down to the same question: what happens to profit and cash if we're wrong? And almost every team answers it the same painful way: by cloning the budget spreadsheet, hand-editing a dozen cells, saving it as "Plan_v3_aggressive_FINAL", and then trying to remember six weeks later what was actually different about it.

The scenarios drift apart. One version flexes revenue but forgets to flex the cost of serving it. Another changes headcount but not the payroll taxes that ride on it. Nobody can say in one sentence what separates the "best case" from the "worst case," because the difference is buried across forty edited cells in a file on someone's laptop. So leadership ends up debating gut feel instead of comparing clean, like-for-like numbers — and the version that becomes "the plan" gets chosen by whoever saved last, not by an actual decision.

A what-if planner fixes the root cause: it makes the assumptions the thing you edit — a handful of transparent, named levers — and computes the P&L and cash for you. Change the lever, see the impact, compare the scenarios honestly, and have leadership pick one on purpose.

What you'll build

A simple internal web app for your FP&A team and leadership. You load your base forecast once — your P&L lines by month, plus a starting cash balance. Then you create scenarios not by editing numbers, but by setting a small set of reusable levers: revenue growth, price change, hiring (heads and start months), churn, and cost cuts. The tool applies those levers to the base and computes each scenario's full P&L and monthly cash for you.

You'll typically build three — best, base, and worst — and see them side by side with the deltas that actually drive decisions: revenue, EBITDA, and cash runway (the month you'd run out, if ever). Every scenario is named, versioned, and reusable, so "the aggressive case" means the same thing to everyone in the room. Leadership reviews the comparison, and approves which scenario becomes the operating plan — a real, recorded decision, not a renamed file. Then you export the scenarios and a clean one-page comparison for the board pack.

What's inside the Implementation Plan

The downloadable plan is a step-by-step file you paste into an AI coding agent. It opens by interviewing you about your business — how your base forecast is shaped and named, which levers actually move your model, how revenue flows into the costs that serve it, your hiring and payroll mechanics, and the messy bits (seasonality, one-off costs, deferred revenue). It reflects a short tailored spec back to you and waits for your thumbs-up before it builds anything, so the levers match how your business really works — not a generic three-column template.

From there it walks the agent through the data model, the base-forecast import, the lever engine, the per-scenario P&L and cash computation, the side-by-side comparison with metric deltas, scenario versioning, the leadership approval gate, and the exports. Every step ends with a ready-to-copy prompt. There's a full "No API yet?" path that uses a Google Sheet / CSV as the base-forecast source and produces clean CSV exports — so you can build and run the whole thing this weekend no matter what planning system you're on.

The governance it includes (this is the point)

Choosing the operating plan is a real decision, so the controls aren't optional. The plan builds in login so only your team can use the tool, row-level security so you only ever see your own organization's numbers, a complete audit trail of who changed which lever and who approved which scenario, a hard human-approval gate so no scenario becomes "the operating plan" until leadership signs off on the comparison, and duplicate guards so the same scenario name can't be created twice and quietly diverge.

Who it's for

FP&A analysts, controllers, CFOs, and finance-owning founders who need to stress-test a plan before a real decision — a fundraise, a hiring wave, a pricing move, or a downturn. If you can describe your base forecast and the few assumptions that actually swing your business, you can build this.

You've got this — start with the plan, paste the first prompt, and answer the interview. You'll have best, base, and worst on one screen before the weekend's out.