Business Case

A structured argument that explains why a project or initiative is worth pursuing — what problem it solves, what it will cost, what it will return, and what happens if you do nothing.

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What is it?

Before anyone builds anything — a product, a feature, a new hire, a warehouse — someone has to answer a deceptively simple question: is this worth doing? A business case is the document that answers it.¹

It is not a business plan (which describes how an entire company will operate over years). A business case is narrower and more decisive: it focuses on one specific initiative and makes the argument for or against investing in it. A founder raising seed funding needs a business plan. A team requesting budget to expand into a new market needs a business case.²

The concept has deep roots in public sector governance. The UK’s HM Treasury developed the Five Case Model in the early 2000s to bring rigour to government spending decisions. It was adopted by the G20 as an international standard for infrastructure projects in 2018 and is now used by governments in New Zealand, Ireland, and beyond.³ The private sector uses simpler variants, but the core logic is the same: before committing resources, prove that the investment is justified.

A good business case does not just argue for an initiative — it makes the decision easier by honestly presenting costs, risks, alternatives, and the consequences of inaction. It protects organisations from spending money on the wrong things and helps teams focus on the right ones.⁴

In plain terms

A business case is a “should we do this?” document. It lays out the problem, the proposed solution, the costs, the expected return, and the risks — so that someone with authority and budget can make an informed decision. If a PRD answers “what are we building?”, a business case answers “why should we build it at all?”

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At a glance

The structure of a business case (click to expand)

graph TD
    P[Problem / Opportunity] --> O[Options Analysis]
    O --> R[Recommended Option]
    R --> CB[Cost-Benefit Analysis]
    R --> RA[Risk Assessment]
    CB --> D{Decision}
    RA --> D
    D -->|Approved| E[Execute]
    D -->|Rejected| F[Revisit or Drop]

    style R fill:#4a9ede,color:#fff
    style D fill:#f0ad4e,color:#fff

Key: Every business case starts with a clearly defined problem, evaluates multiple options, recommends one, and supports the recommendation with financial and risk analysis. The decision-maker then approves, rejects, or requests revision.

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How does it work?

The problem statement — why are we here?

Every business case begins by describing the problem or opportunity that triggered it. This is not a vague aspiration (“we should grow”) — it is a specific, evidence-backed statement of what is wrong or what is possible.¹

A strong problem statement answers three questions:

1. What is happening (or not happening) right now?
2. Who is affected and how?
3. What happens if we do nothing?

The “do nothing” scenario is critical. It establishes the baseline against which every option is measured. Sometimes the honest answer is that doing nothing is the best choice — and a good business case surfaces this rather than hiding it.⁵

Think of it like...

A doctor’s diagnosis before prescribing treatment. You would not accept a prescription without understanding the condition. The problem statement is the diagnosis — it names the ailment, explains the symptoms, and establishes what happens if left untreated.

Options analysis — what could we do?

A business case never presents a single option. It evaluates at least three alternatives:³

Option	Purpose
Do nothing	The baseline — what happens if we take no action
Do minimum	The smallest intervention that addresses the problem
Recommended option	The preferred approach, with full justification
Alternative(s)	Other viable approaches that were considered and rejected

Presenting alternatives builds credibility. It shows decision-makers that the recommendation was not predetermined but emerged from genuine analysis. Each option should be evaluated against the same criteria: cost, benefit, risk, feasibility, and strategic alignment.⁴

Example: options for an e-commerce platform (click to expand)

A small retailer selling handmade goods at markets wants to sell online. Their business case might evaluate:

Option	Cost	Benefit	Risk
Do nothing (keep selling at markets only)	None	None — but losing potential revenue	Competitors move online
Sell via Etsy/Amazon marketplace	Low setup, ongoing fees	Immediate audience, no tech overhead	Platform dependency, margin erosion
Build a Shopify store	Medium setup, monthly fee	Own brand, own customer data	Requires marketing investment
Build a custom website	High setup, ongoing maintenance	Full control	Over-engineered for current scale

The business case would likely recommend Shopify as the best balance of cost, control, and scalability at this stage.

Cost-benefit analysis — does the maths work?

This is the quantitative heart of the business case. It answers two questions: how much will it cost? and how much will it return?⁶

Costs include:

• Capital costs — one-time investments (equipment, software, setup)
• Operating costs — recurring expenses (subscriptions, staff, maintenance)
• Opportunity costs — what you cannot do because resources are committed here

Benefits include:

• Tangible benefits — measurable outcomes (revenue increase, cost reduction, time saved)
• Intangible benefits — harder to measure but real (brand reputation, customer satisfaction, employee morale)

The analysis typically projects costs and benefits over a 3-5 year window, because most investments take time to pay off. Two key metrics emerge:⁶

• ROI (Return on Investment) — the percentage gain relative to the cost. An ROI of 150% means for every dollar invested, you get $1.50 back on top of your original dollar.
• Payback period — how long until the investment pays for itself. A 14-month payback means you recover your investment after 14 months; everything after that is net gain.

Rule of thumb

Be conservative with benefits and generous with costs. Decision- makers trust a business case that under-promises and over- delivers far more than one that paints a rosy picture.⁷

Risk assessment — what could go wrong?

Every initiative carries risk. A business case that ignores risk looks naive; one that addresses it looks credible.¹

For each significant risk, document:

Element	What to capture
Risk	What could go wrong
Likelihood	How probable (high / medium / low)
Impact	How severe if it happens
Mitigation	What you will do to reduce or manage it

Common categories of risk include:

• Market risk — demand does not materialise
• Technical risk — the solution does not work as expected
• Financial risk — costs exceed estimates
• Operational risk — the team cannot deliver
• Regulatory risk — rules change

Think of it like...

A seatbelt in a car. You do not wear a seatbelt because you expect to crash — you wear it because acknowledging the possibility and preparing for it is the responsible thing to do. Risk assessment is the seatbelt of project planning.

The Five Case Model — a comprehensive framework

The most rigorous approach to business casing is the Five Case Model, developed by HM Treasury and adopted internationally. It examines an initiative through five lenses:³

graph LR
    S[Strategic Case] --> E[Economic Case]
    E --> C[Commercial Case]
    C --> F[Financial Case]
    F --> M[Management Case]

    style S fill:#5cb85c,color:#fff
    style E fill:#4a9ede,color:#fff
    style C fill:#f0ad4e,color:#fff
    style F fill:#d9534f,color:#fff
    style M fill:#9b59b6,color:#fff

Case	Question it answers
Strategic	Does this align with our goals and priorities?
Economic	Which option delivers the best value for money?
Commercial	Can this be procured and delivered practically?
Financial	Can we afford it? What is the funding model?
Management	How will it be delivered, governed, and measured?

Not every business case needs all five cases in full. A startup deciding whether to build a feature might focus on the strategic and economic cases. A government investing millions in infrastructure needs all five.³

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Why do we use it?

Key reasons

1. It forces honest thinking before spending. Without a business case, decisions are driven by enthusiasm, politics, or whoever argues loudest. A business case replaces opinion with evidence and makes assumptions explicit.⁴

2. It enables comparison. When multiple projects compete for the same budget, business cases create a common language for evaluating them. Decision-makers can compare apples to apples instead of gut feelings to gut feelings.⁵

3. It protects against sunk-cost traps. Because the business case documents the expected return before work begins, it provides a benchmark to measure against. If reality diverges from the case, the organisation can stop early rather than throwing good money after bad.⁷

4. It aligns stakeholders. Writing a business case forces different parts of an organisation to agree on the problem, the priorities, and what success looks like — before anyone commits resources.¹

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When do we use it?

• When requesting budget for a new project, feature, or hire
• When choosing between competing initiatives with limited resources
• When launching a new product or entering a new market
• When justifying a technology investment (new platform, tool, or infrastructure)
• When a stakeholder asks “why should we do this?” and you need a structured answer
• When pivoting or killing a project — the business case for stopping can be as important as the one for starting

Rule of thumb

If the decision is reversible and low-cost, just try it. If it commits significant time, money, or reputation, write a business case first — even a short one. The discipline of writing it often reveals flaws that enthusiasm hides.

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How can I think about it?

The holiday analogy

Planning a holiday is a miniature business case. The problem: you are burnt out and need a break. The options: stay home and rest (do nothing), take a weekend trip (do minimum), fly somewhere for a week (recommended), take a month off and travel the world (ambitious alternative). The cost-benefit analysis: the week-long trip costs $2,000 but the mental health and productivity return is worth it. The risk: your flight gets cancelled (mitigation: travel insurance). The do-nothing consequence: burnout worsens and your work suffers.

• Problem statement = “I’m burnt out”
• Options = stay home, weekend, week, month
• Cost-benefit = money vs wellbeing
• Risk = cancellations, weather, illness
• Decision = book the week trip

The courtroom analogy

A business case is like a lawyer presenting their argument to a judge. The lawyer (author) does not get to decide — the judge (decision-maker) does. The lawyer’s job is to present the evidence (costs, benefits, risks), acknowledge the opposing arguments (alternatives, do-nothing), and make the strongest possible case for their recommendation — while being honest about weaknesses. A lawyer who hides risks loses credibility. A lawyer who presents only one option looks unprepared. The best lawyers make the judge’s decision easy, not manipulated.

• Lawyer = business case author
• Judge = decision-maker / sponsor
• Evidence = data, projections, analysis
• Opposing arguments = alternatives and risks
• Verdict = approved, rejected, or revised
• Precedent = the business case becomes a reference for future decisions

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Concepts to explore next

Concept	What it covers	Status
cost-benefit-analysis	How to quantify and compare the costs and benefits of different options	stub
risk-assessment	How to identify, evaluate, and mitigate project risks	stub
stakeholder-analysis	How to identify who is affected by a decision and what they need	stub
prd	What to build and for whom — the next document after a business case is approved	complete
scope-management	How to control what is in and out of a project once approved	complete
unit-economics	The financial building blocks (CLV, CAC, margins) that feed into a business case	complete

Some of these cards don't exist yet

They’ll be created as the knowledge system grows. A broken link is a placeholder for future learning, not an error.

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Check your understanding

Test yourself (click to expand)

1. Explain the difference between a business case and a business plan. When would you use each?
2. Name the five dimensions of HM Treasury’s Five Case Model and describe what question each one answers.
3. Distinguish between tangible and intangible benefits. Give two examples of each for an e-commerce project.
4. Interpret this scenario: a startup founder skips the business case and jumps straight to building because “speed matters more than process.” Six months later, the product has no users and the team is out of money. Using what you have learned, explain what a business case would have revealed before building started.
5. Connect this concept to unit-economics. How do metrics like CLV, CAC, and contribution margins feed into the cost-benefit analysis of a business case?

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Where this concept fits

Position in the knowledge graph

graph TD
    PR[Product Requirements] --> BC[Business Case]
    PR --> PRD[PRD]
    PR --> TS[Technical Specification]
    BC --> CBA[Cost-Benefit Analysis]
    BC --> RA[Risk Assessment]
    BC --> SA[Stakeholder Analysis]
    BC -.->|justifies| PRD
    BC -.->|informs| SM[Scope Management]
    style BC fill:#4a9ede,color:#fff

Related concepts:

• prd — once a business case is approved, the PRD defines what to build. The business case is “should we?” and the PRD is “what exactly?”
• scope-management — the business case establishes the boundaries of what was approved; scope management enforces them during delivery
• unit-economics — CLV, CAC, and contribution margins are the financial building blocks that make a business case’s cost-benefit analysis credible

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Sources

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Further reading

Resources

• The Beginner’s Guide to Writing a Business Case (Asana) — Step-by-step guide with examples, ideal for first-timers
• How to Write a Business Case (Atlassian) — Practical walkthrough with template, focused on tech teams
• The Five Case Model Overview — The official site for HM Treasury’s five-case framework
• Five Steps to Develop a Solid Business Case (Chase Group) — Concise five-step process with worked examples
• How to Write a Business Case (Notion) — Modern, template-driven guide for startups and small teams

Footnotes

1. Asana. (2025). The Beginner’s Guide to Writing a Business Case. Asana Resources. ↩ ↩² ↩³ ↩⁴

2. Business Case Analysis. (2025). Business Case vs Business Plan: Know the Difference. Business Case Analysis. ↩

3. APMG International. (2025). The Five Case Model: A Global Standard for Smarter Public Investment. APMG International. ↩ ↩² ↩³ ↩⁴

4. Atlassian. (2025). How to Write a Business Case?. Atlassian Workstream. ↩ ↩² ↩³

5. ProjectManager. (2025). How to Write a Business Case (Example & Template Included). ProjectManager. ↩ ↩²

6. Project-Management.info. (2025). Cost-Benefit Analysis for Business Cases (Definition, Steps, Example). Project-Management.info. ↩ ↩²

7. Adobe Workfront. (2025). How to Write a Business Case: Template & Examples. Adobe. ↩ ↩²