What Is Cost-Benefit Analysis in a Business Case?

Cost-benefit analysis (CBA) systematically compares the costs and benefits of an option over its assessment period to determine whether its benefits justify its costs. It expresses costs and benefits in monetary terms where credible valuation is possible and accounts for when they occur.

In a business case, cost-benefit analysis helps compare feasible options against a base case, usually business as usual or do minimum option. It supports the selection of a preferred option, rather than simply justifying an option already chosen.

What Costs and Benefits Should Be Included?

Assess the additional costs and benefits of each option compared with the base case.

Relevant costs may include development, purchase, implementation, training, operation, maintenance and eventual disposal. They may also include the opportunity cost of resources that could be used elsewhere.

Benefits may include reduced operating costs, increased output, improved service outcomes, time savings, avoided losses or reduced environmental harm.

Use a consistent assessment period and clearly explain the evidence and assumptions behind the estimates. Avoid counting the same benefit twice—for example, counting both staff time savings and the full productivity improvement arising from those same hours.

Financial Analysis and Economic Cost-Benefit Analysis

The perspective of the analysis determines which costs and benefits are included.

Financial analysis focuses on the costs, revenues, savings and cash flows affecting the organisation. It helps assess financial returns and affordability.

Economic cost-benefit analysis takes a wider perspective, considering the effects on the relevant community or society. It may include benefits such as improved safety, reduced travel time or better environmental outcomes, even where these do not generate income for the organisation.

An option can deliver substantial public value without generating a positive financial return for the organisation delivering it. Keep these perspectives clear rather than combining financial and societal benefits without explaining the scope.

How Are Costs and Benefits Compared?

Costs and benefits often occur in different years. Discounting converts future amounts into present values so they can be compared on a consistent basis.

Two commonly used measures are:

• Net present value (NPV): The present value of benefits minus the present value of costs. A positive NPV means the assessed monetary benefits exceed the assessed costs at the chosen discount rate.

• Benefit-cost ratio (BCR): The present value of benefits divided by the present value of costs. A BCR greater than 1 means the assessed monetary benefits exceed the assessed costs.

Use the discount rate and calculation conventions appropriate to your organisation or applicable appraisal guidance. The highest BCR does not necessarily identify the best option, particularly when options differ substantially in scale.

Example: A New Production System

Suppose a business is considering replacing its existing production equipment. After allowing for the costs and benefits of keeping the old equipment, the replacement would add $1 million in costs and $1.4 million in benefits over the assessment period. Both figures have been discounted to present values.

Its:

• NPV is $400,000: $1.4 million minus $1 million.

• BCR is 1.4: $1.4 million divided by $1 million.

This indicates that the assessed benefits exceed the costs under the stated assumptions. Decision-makers must still consider affordability, risk, deliverability and whether another option offers greater overall value.

What About Benefits That Cannot Be Reliably Valued?

Not every important outcome can be credibly expressed in dollars. Describe benefits and adverse effects that cannot be monetised, quantify them in other meaningful units where possible, and explain how they influence the recommendation.

For example, report changes in service accessibility, customer satisfaction or environmental outcomes alongside the financial and economic results. Avoid assigning unsupported monetary values simply to improve the calculated return.

How Should Uncertainty Be Tested?

Sensitivity analysis tests how changes in key assumptions affect the results and identifies which assumptions matter most.

Scenario analysis examines performance under different plausible combinations of conditions, such as higher costs, delayed implementation and lower benefits.

Together, these analyses help decision-makers understand whether an option remains worthwhile when assumptions change.

Use our Financial Analysis Templates to structure your financial calculations and test the assumptions supporting your business case.