A business case is the argument that an investment will return more than it costs, expressed in financial terms the decision-maker uses. It states the problem, the cost of leaving it unsolved, the proposed solution, the expected return, and the payback period.

A proposal lists what you will do. A business case explains what it is worth. Founders and CFOs approve business cases, not scopes of work. If your proposal cannot survive the question what do I get back and when, it is not a business case, and it will lose to the safer option of doing nothing.

Example:

Not: here are twelve deliverables for $10k a month. Instead: this investment is designed to produce a pipeline that returns its cost within nine months and grows revenue beyond it.

What is the difference between a proposal and a business case?

A proposal describes the work. A business case quantifies the return, the payback period, and the cost of not acting, in the financial language the approver uses.

What must a business case include?

The problem, the cost of inaction, the proposed solution, the expected financial return, and how long it takes to pay back.