Business case analysis BCA can be defined as a decision support and planning tool that projects the likely financial results and other business consequences of an action. The analysis essentially asks “What happens if we take this or that action?" The analysis answers in business terms—business costs, business benefits, and business risks.

The word case in the term signals that BCA results are often used with proposals, or arguments, to “make the case” for taking action or for choosing one decision option over another. The shorter term, business case, can be defined as a recommendation for action based on BCA results.

Some business people use the terms cost benefit analyis, financial justification, total cost of ownership, or return on investment analysis to emphasize the special purpose of the study, though what is usually meant by these terms fits the business case analysis (BCA) definition above. While all are essentially "business cases," decision makers and analysts should remember that none of these terms is supported by universally agreed standards. Individual organizations and companies sometimes establish their own standards for content, structure, and the case building process, but cases built elsewhere, under other local standards, can be quite different.

Business case results support decision making and planning, but they also provide valuable guidance for managing and controlling projects, programs, or the life cycle of assets. Good case analysis, for instance, shows which critical success factors and contingencies are most important in controlling business results, measures risks and uncertainties, and provides early warning indicators when the risks of schedule slip, cost overruns, or delayed benefits threaten to rise (see, for instance Project Schedule Monitoring).

Finally, good case analysis provides a strong form of accountability for decision makers and leaders who must show, either now or in the future, that the business decisions made today are good business decisions, based on currently available information and currently reasonable assumptions.

A serious case for a complex business environment requires assumptions, arbitrary judgments, and the development of new data–new information that goes beyond existing budgets and business plans. This means that two people working independently can evaluate the same proposed scenarios, use correct financial math, and still produce quite different case results. For that reason, the business case should also communicate the methods and assumptions underlying projected results.

The following sections present an overview of business case structure, content, and usage (excerpted from Business Case Essentials, 4th Ed ISBN 978-1-929500-12-3)