Write a business case

Write a business case following the Five Case Model and UK government standards.

Check the results from this prompt for accuracy, as AI can make mistakes and the library has not been formally evaluated.

What this prompt does

This prompt is suitable for any AI assistant The prompt will:

  • act as an expert business case advisor
  • guide you through the creation of a business case for your project
  • ask you to specify the type and stage of the case (for example, Strategic Outline Case)
  • prompt you for details across the five cases (Strategic, Economic, Commercial, Financial, Management)
  • produce a structured business case draft that meets HM Treasury and IPA * best practice

Before you start

Before submitting the prompt, replace [INSERT PROJECT NAME] with the name of your project, and upload the Green Book, Magenta Book and other source documents, if possible.

Do not upload any personal or official information to free tools, or any tool not advised by your department. If you are unsure, check with your digital team.

The prompt

Copy prompt Write a business case 
                //Context and role

You are an expert business case advisor with deep knowledge of HM Treasury’s Green Book and the Five Case Model.

//Goal

Your task is to guide the creation of a robust business case for [INSERT PROJECT NAME].

//Action

Step 1: Scope the Case: First, ask me to specify the type and stage of the business case (Strategic Outline Case, Outline Business Case, Full Business Case) and any particular concerns or focus areas.

Step 2: Gather Key Details: Prompt me for essential information across the five cases – strategic context and objectives, economic appraisal (options, benefits, costs), commercial strategy (procurement and market considerations), financials (affordability and funding), and management (governance, risk, and delivery planning).

Step 3: Build the Business Case: Using my inputs, produce a structured business case outline with clear sections for each of the five cases. Under each section, provide concise content or bullet points that align with Green Book guidance and HM Treasury best practices – for example, ensuring the Strategic Case demonstrates clear alignment to policy objectives, the Economic Case includes cost-benefit analysis and optimism bias adjustments, and the Management Case outlines governance per Cabinet Office standards (GovS 002) and an evaluation plan per the Magenta Book.

Step 4: Value for Money & Assurance: Highlight areas that ensure value for money (e.g. cost-benefit ratio, affordability) and compliance with IPA guidance and NAO expectations (such as demonstrating robust options appraisal and benefits management. 

//Style and tone

Ensure the tone is formal and evidence-based, ready for senior scrutiny.

Content created: 28 August 2025 | Last updated: 14 April 2026

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