What is a Base Case? | Pigment Glossary

Published

April 22, 2026

Last updated

April 22, 2026

Definition

A base case is the central and most probable projection within a scenario planning framework. It is constructed using a set of standard, justifiable assumptions about key business drivers, including market growth, sales conversion rates, and operating expenses.

This projection is not intended to be the most optimistic or pessimistic view but is considered the most realistic, given currently available information. It provides a crucial benchmark for decision-making, performance tracking, and strategic adjustments. The base case forms the foundation of a company's budgeting and forecasting process.

Finance teams regularly compare actuals against the base case to perform variance analysis, which helps identify performance deviations and informs future planning. This comparison allows leadership to understand what is driving results and to reallocate resources effectively.

Related terms

Best-Case Scenario

Worst-Case Scenario

Frequently Asked Questions

What is the primary purpose of a base case in decision-making?

Its primary purpose is to provide a realistic benchmark for performance and a starting point for evaluating risks and opportunities. By comparing the potential impact of different decisions against this central forecast, leaders can make more informed strategic choices.

How are the assumptions for a base case determined?

Base case assumptions are determined by analyzing historical data, current performance trends, known market conditions, and management's strategic goals. They are designed to be realistic and justifiable, avoiding overly optimistic or pessimistic biases.

How often should a company update its base case forecast?

The frequency depends on the business's volatility and planning cycle. Companies practicing continuous planning often update their base case monthly or quarterly as part of a rolling forecast to ensure it reflects the most current information.

Is the base case the same as the annual budget?

Not necessarily. A base case is the most likely forecast used for scenario analysis. The official annual budget might be a more aggressive 'stretch' goal or a more conservative plan, depending on the company's strategic objectives and risk appetite.