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Overview

The /arckit.sobc command creates a Strategic Outline Business Case (SOBC) to justify investment in a technology project using the HM Treasury Green Book 5-case model.

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When to Use

  • Phase: Phase 4 - Business Case Justification
  • Timing: AFTER stakeholders and risk assessment, BEFORE detailed requirements
  • Purpose: Secure executive approval and funding to proceed with detailed requirements and design

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Business Case Lifecycle

ArcKit supports the UK Government business case lifecycle:
  • SOBC (Strategic Outline): High-level case for change, done BEFORE detailed requirements — this command
  • OBC (Outline Business Case): After some design work, with refined costs
  • FBC (Full Business Case): Detailed case with accurate costs, ready for final approval

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Command Usage

/arckit.sobc <project ID or initiative>

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Examples

# Create SOBC for existing project
/arckit.sobc 001

# Cloud migration programme
/arckit.sobc cloud migration programme

# New initiative
/arckit.sobc Create SOBC for payment modernization

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Interactive Configuration

The command asks you:
  1. Strategic Options:
    • 4 options (Recommended): Do Nothing + Minimal + Balanced + Comprehensive
    • 3 options: Do Nothing + two alternatives
    • 5 options: Do Nothing + four alternatives (complex programmes)
  2. Appraisal Depth:
    • Strategic estimates (Recommended): ROM costs and qualitative benefits
    • Semi-quantitative: ROM costs with quantified key benefits and basic NPV
    • Full quantitative: Detailed costs, quantified benefits, NPV, BCR, sensitivity analysis

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The 5-Case Model

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A. Strategic Case

Answers: “Why must we do this?”
  • Problem Statement: What’s broken? (from stakeholder pain points)
  • Strategic Fit: How does this align with organizational strategy?
  • Stakeholder Drivers: Map to stakeholder analysis
    • Link EACH driver to strategic imperative
    • Show intensity (CRITICAL/HIGH/MEDIUM)
  • Scope: What’s in/out of scope (high-level)
  • Dependencies: What else must happen?
  • Why Now?: Urgency and opportunity cost
Example: 
### Problem Statement
Legacy payment system processes 500 transactions/day with 7-day settlement. 
CFO faces £2M annual operational cost (D-1: Reduce costs - FINANCIAL, HIGH).
Customers complain about slow refunds (D-7: Improve satisfaction - CUSTOMER, HIGH).

### Why Now?
- Current system EOL in 18 months (vendor support ending)
- Competitor offers 2-hour settlement (market pressure)
- PCI-DSS 4.0 compliance required by 2025 (regulatory deadline)

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B. Economic Case

Answers: “What are the options and which gives best value?” Options Analysis (CRITICAL):
  • Option 0: Do Nothing (baseline)
  • Option 1: Minimal viable solution
  • Option 2: Balanced approach (often recommended)
  • Option 3: Comprehensive solution
For EACH option:
  • High-level costs (rough order of magnitude)
  • Benefits delivered (% of stakeholder goals met)
  • Risks
  • Pros/cons
Benefits Mapping:
  • Link EACH benefit to specific stakeholder goal from ARC-{PROJECT_ID}-STKE-v*.md
  • Quantify where possible (use stakeholder outcomes for metrics)
  • Categorize: FINANCIAL | OPERATIONAL | STRATEGIC | COMPLIANCE | RISK
Example: 
### Benefit B-1: £2M Annual Cost Savings
**Category**: FINANCIAL
**Stakeholder Goal**: CFO Goal G-1: Reduce processing time 7d → 2d
**Quantification**: 
- Current: 20 FTE × £100K = £2M
- Target: 13 FTE × £100K = £1.3M (30% reduction)
- Annual Savings: £700K
**Timeline**: Year 1: £200K, Year 2: £500K, Year 3: £700K
**Measurement**: Monthly FTE count and cost tracking
**Risk**: Medium (depends on successful change management)
Cost Estimates (high-level):
  • Capital costs (build)
  • Operational costs (run)
  • 3-year TCO estimate
Economic Appraisal:
  • Qualitative assessment (this is strategic, not detailed)
  • Expected ROI range
  • Payback period estimate
Recommended Option: Which option and why

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C. Commercial Case

Answers: “How will we procure this?” Procurement Strategy:
  • UK Government: Digital Marketplace route (G-Cloud, DOS, Crown Hosting)
  • Private Sector: Build vs Buy vs Partner
Market Assessment:
  • Supplier availability
  • SME opportunities (UK Gov requirement)
  • Competition considerations
Sourcing Route: How will we acquire this? Contract Approach: Framework, bespoke, managed service? Example: 
### Procurement Strategy
**Route**: Digital Marketplace G-Cloud 14
**Rationale**: 
- 150+ payment gateway suppliers available
- Pre-competed framework (faster procurement)
- SME-friendly (60% of suppliers)
- Compliant with TCoP Point 11 (Purchasing Strategy)

### Shortlist Criteria
- PCI-DSS Level 1 certification (MANDATORY)
- UK data residency (MANDATORY)
- 99.99% uptime SLA (MUST)
- Open Banking API support (SHOULD)

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D. Financial Case

Answers: “Can we afford this?” Budget Requirement: How much needed? Funding Source: Where does money come from? Approval Thresholds: Who must approve?
  • UK Gov: HMT approval needed above £X?
  • Private: Board approval needed?
Affordability: Can organization afford this? Cash Flow: When do we need money? Budget Constraints: Any spending controls? Example: 
### Investment Summary (3-year)
**CAPEX** (Year 1):
- Software licenses: £500K
- Implementation: £800K
- Data migration: £200K
- **Total CAPEX**: £1.5M

**OPEX** (per annum):
- Managed service: £300K/year
- Support contracts: £100K/year
- Cloud hosting: £200K/year
- **Total OPEX**: £600K/year

**3-Year TCO**: £1.5M + (£600K × 3) = £3.3M

**Funding Source**: Spending Review 2024 settlement (confirmed)
**Approval**: CFO (< £5M threshold), no HMT approval needed

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E. Management Case

Answers: “Can we deliver this?” Governance:
  • Who owns this? (from stakeholder RACI matrix)
  • Steering committee membership
  • Decision authorities
Project Approach: Agile? Waterfall? Phased? Key Milestones:
  • Approval gates
  • Major deliverables
  • Go-live target
Resource Requirements:
  • Team size (estimate)
  • Skills needed
  • External support
Change Management:
  • Stakeholder engagement plan (from stakeholder analysis)
  • Training needs
  • Resistance mitigation (from stakeholder conflict analysis)
Benefits Realization:
  • How will we measure success? (use stakeholder outcomes)
  • Who monitors benefits?
  • When do we expect to see benefits?
Risk Management:
  • Top 5-10 strategic risks
  • Mitigation strategies
  • Risk owners (from stakeholder RACI)
Example: 
### Governance
**SRO**: CFO (Accountable - from RACI)
**Project Board**:
- CFO (Chair)
- CTO (Technology authority)
- Operations Director (Service delivery)
- Finance Director (Budget holder)
**Meeting Frequency**: Monthly

### Risk Management
**Top Risks** (from ARC-{PROJECT_ID}-RISK-v*.md):
- R-001: Vendor lock-in (TECHNOLOGY, High, 16) → CTO mitigation: Open standards
- R-003: Cost overrun (FINANCIAL, High, 15) → CFO mitigation: Stage-gate approvals
- R-007: Change resistance (OPERATIONAL, Medium, 12) → Ops mitigation: Co-design workshops

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Traceability to Stakeholders

Every element must link back to stakeholder analysis: 
Stakeholder Driver D-1 (CFO: Reduce costs - FINANCIAL, HIGH)
  → Strategic Case: Cost pressure driving change
    → Economic Case: Benefit B-1: £2M annual savings (maps to CFO Goal G-1)
      → Financial Case: 18-month payback acceptable to CFO
        → Management Case: CFO sits on steering committee (RACI: Accountable)
          → Success Criterion: CFO Outcome O-1 measured monthly

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Decision Framework

  • Recommendation: Which option to proceed with?
  • Rationale: Why this option? (reference stakeholder goals met)
  • Go/No-Go Criteria: Under what conditions do we proceed?
  • Next Steps: If approved, what happens next?
    • Typically: /arckit.requirements to define detailed requirements
    • Then: /arckit.business-case-detailed with accurate costs

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UK Government Specifics

For UK Government/public sector projects:

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Strategic Case Includes

  • Policy alignment (manifesto commitments, departmental objectives)
  • Public value (not just efficiency, but citizen outcomes)
  • Minister/Permanent Secretary drivers
  • Parliamentary accountability

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Economic Case Includes

  • Social Cost Benefit Analysis (if required)
  • Green Book discount rates (3.5% standard)
  • Optimism bias adjustment (add contingency)
  • Wider economic benefits

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Commercial Case Includes

  • Digital Marketplace assessment (G-Cloud, DOS)
  • SME participation commitment
  • Social value (minimum 10% weighting)
  • Open source consideration

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Financial Case Includes

  • HM Treasury approval thresholds
  • Spending Review settlement alignment
  • Value for money assessment
  • Whole-life costs

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Management Case Includes

  • Service Standard assessment plan
  • GDS/CDDO engagement
  • Cyber security (NCSC consultation)
  • Accessibility (WCAG 2.2 AA compliance)
  • Data protection (ICO/DPIA requirements)

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Output File

Creates: projects/{project}/ARC-{PROJECT_ID}-SOBC-v1.0.md Contains:
  • Executive Summary (2-3 pages)
  • Strategic Case: Why we need to act (10-15 pages)
  • Economic Case: Options and value for money (15-20 pages)
  • Commercial Case: Procurement approach (5-10 pages)
  • Financial Case: Funding and affordability (5-10 pages)
  • Management Case: Delivery capability (10-15 pages)
  • Appendices: Stakeholder analysis, risk register, assumptions
Total Length: Executive-ready for senior leadership and Treasury approval

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Prerequisites

MANDATORY (command will warn if missing):
  • STKE (Stakeholder Analysis) - SOBC must link to stakeholder goals
If stakeholder analysis doesn’t exist:
  • DO NOT proceed with SOBC
  • Tell user: “SOBC requires stakeholder analysis to link benefits to stakeholder goals. Please run /arckit.stakeholders first.”
RECOMMENDED (read if available):
  • PRIN (Architecture Principles) - Strategic alignment
  • RISK (Risk Register) - Risks for Management Case

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Common Patterns

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Pattern 1: Technology Modernization

  • Strategic Case: Legacy systems failing, stakeholder frustration high
  • Economic Case: 3-5 options from do-nothing to complete rebuild
  • Commercial Case: Cloud migration, Digital Marketplace G-Cloud
  • Financial Case: £2-5M over 3 years, CFO approval needed
  • Management Case: Phased migration, minimal disruption

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Pattern 2: New Digital Service

  • Strategic Case: Citizen/customer demand, competitive pressure
  • Economic Case: MVP vs full-featured comparison
  • Commercial Case: Build in-house vs platform vendor
  • Financial Case: £500K-2M year 1, ongoing £200K/year
  • Management Case: Agile delivery, beta to live

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Pattern 3: Compliance/Risk Driven

  • Strategic Case: Regulatory requirement, audit findings
  • Economic Case: Minimum compliance vs best practice
  • Commercial Case: Specialist vendors, certification needed
  • Financial Case: Non-negotiable spend, insurance cost reduction
  • Management Case: Deadline-driven, stakeholder compliance team owns

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Quality Checks

Before delivery, verifies:
  • All benefits trace to stakeholder goals
  • At least 3 options evaluated (including Do Nothing)
  • Costs estimated for 3-year period
  • Procurement route identified
  • Funding source confirmed
  • Governance structure defined with RACI
  • Top 5-10 risks included from risk register
  • Benefits realization plan included
  • Recommendation clear with rationale

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Next Steps

After creating SOBC:
  1. Present to Senior Responsible Owner (SRO) for approval
  2. Present to Architecture Board
  3. If approved: Run /arckit.requirements to define detailed requirements
  4. After requirements: Refine to Outline Business Case (OBC) with firmer costs
  5. After design: Create Full Business Case (FBC) for final approval

Stakeholders

MANDATORY prerequisite for benefit mapping

Risk Management

Risk register feeds Management Case Part E

Requirements

Next step after SOBC approval

Roadmap

Strategic roadmap from investment plan

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Example Outputs

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Key References

See Codes of Practice guide for full Rainbow of Books mapping.