I suppose for a non-contentious start I could open up with the question “What is a Business Case?” And for an answer I quite like the Prince2 definition, which goes along the lines
“The Business Case presents the optimum mix of information used to judge whether (a proposed) project is desirable, viable and achievable and therefore worth investing in.”
And goes on to say
“Since this viability question is on-going, the Business Case is not static. It should not be used only to gain initial funding for the project, but should be actively maintained throughout the life of the project and be continually updated with current information on costs, risks and benefits.”
The key elements of the Business Case are the on-going benefits the ongoing costs, and the one-time costs and benefits. Contents of the Business Case from Prince2 perspective are broader and cover:
– The reasons for undertaking the project with link to business strategies and objectives.
– Business options including do nothing, do the minimum, aswell do something.
– Expected disbenefits, which are negative outcomes of the project
– Major risks.
The business case financial model should project costs and benefits across the life expectancy of the new system. Consider including inflation, interest rates, market growth rates and so on. If the life expectancy exceeds several years, consider a more formal financial analysis such as net present value.