Official skill · Finance

Financial model assumptions review

v1.0.0 · Updated 4 November 2026

Reviews a financial model's assumptions: lists each with its source, tests sensitivity, checks plausibility against history, and names the 3 that matter. Use it when before a model goes to the board, a lender, or investors.

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When to use it

Before a model goes to the board, a lender, or investors
A forecast looks too good and nobody can say why

What you give it

The model or its inputs and outputs
Actual history for the same drivers
Benchmarks you trust, with sources (optional)

What you get

A review with the top 3 assumptions, a sensitivity table, a full assumptions log, and structural issues.

How it works

List every assumption Include hard-coded numbers inside formulas, not only the inputs tab. For each: what it is, value, unit, period, source (history, contract, plan, guess), and who set it. Our default: if the source is blank, mark it "guess".
Separate drivers from results Drivers are inputs (conversion rate, price, churn, hiring plan, salary). Results are computed (revenue, burn). Flag any result typed in as a number instead of computed.
Run sensitivity one input at a time For each driver, change it by a set step (our default: ±20%, or a realistic range the user gives) and record the change in the key output. Rank drivers by the size of that change.
Check plausibility Compare each top driver to the company's own history: a growth rate double the best month so far, or churn half of history, needs a reason. Compare to user-given benchmarks, citing them. If neither exists, write "[check: no history or benchmark]".
Name the 3 that matter most The 3 drivers with the largest effect on the key output, each with: current value, the evidence for it, what happens to the output if it's wrong in the downside direction, and what would raise confidence (data to gather, a test to run).
Note structural issues Units that don't match (monthly vs annual), timing (hires starting at month 1 of the plan with no recruiting time), drivers that should depend on each other but don't (sales hires up, quota per rep unchanged, revenue doesn't move).
Write the summary 2 to 3 sentences: what the model says, the 3 assumptions it rests on, and the biggest risk.

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