How to Use Scenario Planning in Your Financial Forecast

The future is uncertain — that's not a bug in financial forecasting, it's the whole point. Scenario planning is the discipline of building multiple versions of the future so you can make decisions that hold up across a range of outcomes.

Why Scenario Planning Matters

Most founders build one forecast: their best guess at how things will go. This is useful, but incomplete. What happens if your top sales rep leaves? What if a major customer churns? What if your CAC doubles because of increased competition? Scenario planning forces you to think through these possibilities before they happen.

The Three Scenarios

A simple framework is to build three scenarios: base, upside, and downside. Your base case should be your most likely outcome — achievable with normal execution. Your upside case should reflect what happens if things go better than expected: faster growth, lower CAC, higher retention. Your downside case should stress-test your assumptions: what's the minimum viable outcome that keeps the company alive?

Key Assumptions to Vary

Not all assumptions are equally important. Focus your scenarios on the levers that have the biggest impact on your model. For most SaaS companies, that means revenue growth rate, churn rate, and headcount growth. For marketplaces, it might be take rate and GMV growth. Identify your top 3–5 assumptions and vary those between scenarios.

Using Scenarios to Make Decisions

The real value of scenario planning isn't the scenarios themselves — it's the decisions they inform. If even your downside case shows 18 months of runway, you can invest aggressively in growth. If your downside case shows 6 months of runway, you need to either raise quickly or reduce burn. Scenario planning gives you the map you need to navigate uncertainty.