Business model · Choose, Plan

Business case and driver model

Builds the number the decision actually turns on, from the four or five drivers that move it. Most business cases are a spreadsheet defending a conclusion somebody reached before opening it.

Stage

03 Choose, 04 Plan

Works at

All levels

Maturity

Early startup → Large organisation

Time

Two to three days if the cost data exists

What it is

A financial case built from the small number of variables that genuinely move the answer, rather than from a full forecast. Volume, price, unit cost and conversion usually carry it between them, and the model exists so that changing one is a five-second question in a meeting rather than a rebuild afterwards. It is the artefact that sensitivity analysis, cost-benefit work and most board papers quietly assume already exists.

The baseline: What happens if you do nothing. Every case is measured against this, and a flattering baseline is the commonest way a weak option gets approved.
The drivers: The four or five variables the answer is genuinely sensitive to. Everything else is arithmetic and should be visibly derived rather than separately assumed.
Assumptions with sources: Each driver's value, where it came from, and how confident anyone is. An unsourced assumption is an opinion with a decimal point on it.
Three cases: Downside, base and upside, differing only in driver values. If somebody has to change the structure to produce the downside, the structure is wrong.
Cash, not only profit: The low point of the cash curve and when it occurs. Businesses fail on this line rather than on the profit line, and the profit line is the one that gets presented.
The break-even question: How far a driver has to move before the answer reverses. This is the sentence a board actually remembers a week later.

The mistake people makeBuilding a full three-statement forecast when the decision turns on four numbers. It takes three times as long, buries the drivers inside the detail, and nobody can sensitise it while the meeting is still running.

What it’s forA decision needs a financial answer and there is no model to sensitise.

What it’s not forThe strategic choice is already made in private. A model built to justify a decision will justify it.

How you run it

Model the do-nothing case firstEverything is measured against it. A baseline that quietly assumes decline is how a weak option starts to look necessary.
Find the drivers before you build anythingAsk which four numbers change the answer. Building first and hunting for drivers afterwards produces a model nobody can move.
Source every assumption on the face of the modelValue, source, date, confidence. Assumptions living in a comment on a hidden tab are always the ones that turn out to be somebody's guess from a year ago.
Build three cases by moving drivers onlyThe structure stays identical across all three. If it does not, you have built three models and can compare none of them.
Report the cash low point and the break-evenPeak funding need, when it lands, and how far each driver can move before the decision reverses. That is the part that changes minds.

The prompt

Two ways to run it

Run this tool in your own Claude

The short prompt starts your partner against the library on your disk. The long one carries everything with it and needs nothing installed.

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🔒 Prompt locked

Everything above is free — what this tool is, what it is for, what it is not for, and how to run it as a workshop. Three tool prompts a month are free with an account; beyond three, and for the printable canvas, it is the paid part.

See plans — from £19 a month

Your playbook

It lands in the earliest stage this tool suits. Move it on the Playbook page.

You’ll need

The option being tested, defined tightly enough to cost
The current baseline — revenue, cost and cash as they actually stand
Honest ranges for each driver, rather than single-point estimates

You’ll end up with

A driver-based model with every assumption visible and sourced
Three cases — downside, base and upside — differing only in the drivers
Payback, the cash low point, and how far a driver can move before the answer flips

Runs well with

Acquisition screen and synergy thesis AI operating model options AI opportunity map AI risk classification and governance