A business case should explain why an investment is expected to create value and what evidence would prove that expectation wrong.
In many organisations, the business case has one dominant purpose: win approval.
Once approval is secured, the document moves into an archive and the project is judged mainly against its delivery baseline. This creates a fundamental governance weakness.
The decision to invest was based on assumptions about cost, benefits, demand, adoption, timing, risk and organisational capacity. Those assumptions do not become true because funding was approved.
The supplied EY portfolio-management material identifies weak scrutiny of business cases and unrealistic benefits as portfolio challenges. It also places business cases inside a wider decision framework that considers strategic fit, economic value, resources, interdependencies and risk.
That is a stronger model. The business case is not a permit to spend. It is an investment hypothesis that should be tested throughout the life of the commitment.
The Strategic Context
Capital decisions are made under uncertainty.
Leaders rarely know the final cost, exact benefit, market response, implementation difficulty or future operating environment with certainty. The purpose of a business case is therefore not to manufacture confidence. It is to structure uncertainty well enough for a responsible decision.
A credible case should make visible:
- what the organisation believes;
- what evidence supports that belief;
- what must be true for value to appear;
- what could cause the investment to fail;
- what alternatives were considered;
- what should trigger reconsideration.
The more irreversible the investment, the more important this discipline becomes.
What Leaders Commonly Misread
The first mistake is treating benefit forecasts as commitments rather than estimates. Forecasts can be disciplined without pretending uncertainty has disappeared.
The second is underestimating implementation conditions. A technology initiative may have a strong technical case but weak adoption logic. A manufacturing investment may have attractive unit economics but depend on demand, quality or supply assumptions that have not been tested.
The third is evaluating a business case in isolation from the portfolio. An initiative can remain economically positive while becoming a poor relative use of scarce resources.
The fourth is allowing the sponsor who wants the project to control both assumptions and challenge. Advocacy is natural; governance requires independent scrutiny.
Reframing the Issue
A business case should be structured as:
Objective → alternatives → assumptions → expected value → risks → evidence → decision thresholds
This makes it possible to revisit the case when evidence changes.
For example, if a project assumes 70 per cent customer adoption, the organisation should know when adoption evidence will become available and what decision follows if the assumption is materially wrong.
This approach turns uncertainty into governable information.
The Assumptions That Matter Most
Not all assumptions deserve equal attention.
Leaders should identify the few assumptions that can materially change the decision.
These may include:
- demand volume;
- implementation cost;
- productivity improvement;
- customer adoption;
- supplier performance;
- regulatory approval;
- workforce availability;
- integration complexity;
- timing of benefits;
- residual value.
The case should state what evidence would validate or invalidate them.
That creates the basis for staged investment.
Decision Framework
Apply five tests before approval.
Strategic test: Does the proposal materially support a current strategic objective?
Alternative test: Has the organisation considered doing nothing, doing less, sequencing differently or using another solution?
Assumption test: Which assumptions drive most of the expected value?
Portfolio test: What does the proposal displace or constrain elsewhere?
Exit test: At what points can the organisation stop or redesign if evidence is unfavourable?
Then apply a continuing-justification review during delivery.
Ask whether the original value logic is strengthening or weakening.
The answer may justify acceleration just as legitimately as termination.
Related article: Portfolio Prioritisation Is Not Ranking: Decide What to Accelerate, Defer and Stop
Avoiding False Precision
Business cases often contain detailed financial models. Detail can improve analysis, but it can also create an illusion of certainty.
A forecast with two decimal places is not more reliable if its core assumptions are speculative.
Executives should therefore pay close attention to sensitivity. Which variables change the decision? How wide is the plausible range? What is the downside if several assumptions fail together?
The supplied sources do not provide a complete contemporary investment-appraisal methodology, so ERANORTH should not prescribe specific financial thresholds from this batch alone.
The durable principle is simpler: decision confidence should be proportional to evidence quality and reversibility.
From Strategy to Execution
Immediately, require major business cases to list critical assumptions and the evidence available for each.
In the medium term, connect those assumptions to delivery and benefit reporting. If the business case depends on adoption, adoption evidence belongs in governance.
Longer term, establish staged funding for highly uncertain initiatives where feasible. Early phases can buy information before the organisation commits fully.
This is especially useful for digital, innovation and transformation investments where uncertainty is high and learning has real option value.
Related article: A Project Can Succeed and the Strategy Can Still Fail
Signals to Monitor
Watch for business cases that contain detailed costs but vague benefits; benefits with no owner; no documented alternatives; assumptions that are never revisited; sponsors defending the original case with sunk-cost arguments; and governance papers that report schedule variance without reporting whether the investment logic has changed.
Another warning sign is when every business case predicts success and the organisation has no record of systematically learning from forecast error.
Questions for the Leadership Team
- What assumptions drive the value of our largest investments?
- What evidence would cause us to change our mind?
- Which projects have business cases that have not been revisited since approval?
- Are alternative solutions genuinely assessed or included merely to support a preferred option?
- Where could staged funding reduce irreversible commitment?
- Do our benefit forecasts become more accurate over time because the organisation learns from prior investments?
Closing Perspective
A business case is strongest when it makes doubt visible.
It should not persuade executives that the future is certain. It should show why the investment is justified despite uncertainty, which assumptions matter and how the organisation will respond when reality differs from the forecast.
That turns approval from a one-time permission to spend into an ongoing discipline of investment judgement.
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