How to build a business case with AI

Define the case for change

Describe the current process, affected users, measured problem, strategic objective, and consequence of doing nothing. Keep facts separate from estimates. Record the baseline period, source, owner, and known data limitations.

HM Treasury’s current business-case guidance uses the Five Case Model: strategic, economic, commercial, financial, and management dimensions. The Green Book also emphasizes comparing options, including business as usual, and considering costs, benefits, risk, and uncertainty. These public-sector methods are useful organizing references, not proof that a private investment is worthwhile.

Build a benefits dependency map

For each claimed benefit, connect:

investment → capability → behavior or process change → measurable outcome → valued benefit

Name the owner, timing, metric, baseline, attribution boundary, and disbenefit. If two benefits depend on the same saved hours, they cannot both claim the full value.

Worked synthetic case

Suppose a team proposes a guided evidence-review tool for assessment reports. Current reviewers spend an estimated 500 hours per year locating source passages. The proposed capability links report statements to evidence records.

Candidate benefits are reduced search time, shorter report turnaround, and increased review capacity. A weak model values all 500 hours as labor savings and then values the same hours again as added report capacity.

A reconciled model chooses explicit scenarios:

| Scenario | Search time recovered | Redeployed to added reviews | Cash saving recognized | | --- | ---: | ---: | ---: | | Downside | 10% | 0% | 0 | | Central | 30% | 60% of recovered time | 0 | | Upside | 45% | 80% of recovered time | 0 |

All values are synthetic. If no staffing cost actually leaves the organization, describe capacity or service benefit rather than cash saving.

Compare real options

Assess business as usual, process improvement without a new tool, buy, build, and phased pilot where feasible. For each option show cost ranges, benefit pathways, delivery dependencies, reversibility, security and operating requirements, and failure conditions. Disqualify options that cannot meet critical constraints before fine-grained scoring.

Reconcile the five dimensions

The strategic case should align the objective and need. The economic case compares options and total effects. The commercial case tests supplier or sourcing viability. The financial case shows affordability and cash timing. The management case identifies delivery, governance, benefits ownership, and evaluation. A strong narrative in one dimension cannot repair missing affordability or delivery capacity in another.

Use AI for challenge analysis

Ask AI to locate duplicated benefits, mixed nominal and real values, inconsistent time horizons, omitted operating costs, circular assumptions, and dependencies with no owner. Then run sensitivity tests on adoption, delay, cost overrun, benefit timing, and exit value.

Write the decision

A responsible conclusion might be: “Authorize a limited pilot and evidence collection, not full investment. The case depends on a 30% reduction in search time, but the baseline sample and integration estimate are not yet sufficient. Reconsider after four weeks of measured workflow data and a verified cost range.”

Verification checklist

Reconcile the baseline; trace each benefit once; include disbenefits; compare business as usual; use consistent time and price bases; test downside scenarios; assign benefit and risk owners; confirm affordability; expose dependencies; and state what evidence would reverse the recommendation.

Sources and claim map

The case, hours, costs, scenarios, and conclusion are synthetic. This resource does not promise savings, adoption, capacity, investment return, or successful delivery.

• HM Treasury, Guidance on developing business cases: supports the current Five Case Model structure and step-by-step business-case process.
• HM Treasury, The Green Book 2026: supports options appraisal, business-as-usual comparison, and explicit consideration of costs, benefits, risk, and uncertainty.

Sources: [1] [2]