Software Technical Due Diligence UK — What Investors & Acquirers Actually Check (2025)
Technical due diligence (TDD) for UK software businesses examines: architecture quality and scalability, code quality and technical debt, security posture (Cyber Essentials, pen test status), UK GDPR compliance (ICO registration, DPAs, data residency), IP ownership (assignment agreements), team capability and key person risk, and operational resilience. TDD is conducted by acquirers in M&A and by investors at Series A and beyond. A poor TDD report can reduce acquisition valuation by 15–40% or kill a deal entirely.
| TDD Area | What Reviewers Check | UK-Specific Angle |
|---|---|---|
| Architecture | Scalability, modularity, technology choices, technical debt | Microservices vs monolith appropriateness for current team size |
| Code Quality | Test coverage, code standards, documentation, maintainability | SOLID adherence, technical debt quantification in days |
| Security Posture | Pen test reports, vulnerability management, Cyber Essentials status | Cyber Essentials certification, CREST pen test date |
| UK GDPR Compliance | ICO registration, DPAs with processors, data residency, DPIA | AWS eu-west-2 or Azure UK South usage, Article 28 DPAs |
| IP Ownership | IP assignment agreements, open source licence audit | CDPA 1988 — contractor-created code may belong to contractor without explicit assignment |
| Team & Bus Factor | Key person dependency, documentation, handover risk | IR35 status of key contributors — liability risk for acquirer |
| Operational Resilience | Monitoring, incident response, backup/DR, SLA capability | FCA PS21/3 relevance for regulated businesses |
| Finding | Frequency | Impact on Valuation |
|---|---|---|
| No IP assignment from contractors/agency | Very common | Can be deal-blocking — acquirer does not own the software it is buying |
| UK GDPR: No Article 28 DPAs with SaaS processors | Common | Risk flag — ICO enforcement liability passes to acquirer |
| No penetration test evidence | Common | Security risk flag — may require escrow or price reduction |
| Significant unaddressed technical debt | Very common | 5–20% valuation reduction — acquirer prices in remediation cost |
| IR35 risk from key contractors inside IR35 | Common | Potential HMRC liability passes to acquirer |
| Cyber Essentials not certified | Common (for regulated/gov businesses) | May disqualify from certain contracts — revenue risk |
| AWS/Azure outside UK region (GDPR) | Common | UK GDPR compliance risk — remediation cost and ICO liability |
What Technical Due Diligence Actually Covers
TDD is not just a code review. A thorough UK technical due diligence covers seven areas:
The Most Common UK TDD Findings
Based on ClickMasters' experience supporting TDD preparation:
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