The honest answer
Technology due diligence costs vary considerably, and anyone who gives you a number without knowing your deal isn't being straight with you. But there are clear ranges for different types of transaction, and understanding them will help you plan your budget and ask the right questions of any adviser you approach.
Typical cost ranges
The fee for technology due diligence is primarily driven by the size and complexity of the deal. Here are the typical ranges across different transaction types.
Pre-LOI or lightweight review: £5,000 to £10,000
A pre-LOI review is a rapid assessment carried out before heads of terms are agreed. The goal is to identify any obvious blockers or material risks that might affect whether you proceed, and at what price. Access to the target is usually limited, so the work draws on public information, company filings, technical footprint, and sometimes a short management call. It's not a substitute for full diligence, but it's a cost-effective way to avoid committing to a process on a target that has structural problems.
Boutique and smaller transaction: £10,000 to £25,000
For smaller deals — typically under £10m enterprise value — a focused scope covering the key risk areas will usually fall in this range. The work covers architecture, team, security basics, and technical debt. It won't include penetration testing or deep code review, but it gives you enough to make an informed decision and build a post-acquisition plan.
Mid-market: £25,000 to £50,000
Mid-market deals between £10m and £100m enterprise value typically require a more thorough exercise: structured management sessions, access to the data room, a detailed technical assessment, and a full written report. This is the range where advisers also spend more time on integration risk, team dependencies, and the commercial implications of what they find. Expect three to five weeks of work.
Large-cap and complex transactions: £50,000 to £100,000+
Large or structurally complex transactions — multi-entity groups, cross-border targets, regulated industries, or businesses with significant legacy infrastructure — require more time and often a broader team. At this end of the market, costs can exceed £100,000, particularly where security testing, code review, or integration workstream support is included. The scope is typically agreed in detail upfront, with a phased approach aligned to the deal timeline.
What drives the cost
Within each range, several factors push the fee up or down. Understanding them helps you have a more productive conversation with any adviser you approach.
Scope. A review limited to architecture, team, and security basics costs less than one that includes code review, security testing, integration planning, or commercial risk analysis. Being clear about what you need — and what you don't — is the fastest way to control cost.
Timeline. Compressed timelines cost more. If you need a full assessment in two weeks rather than four, expect a premium. Diligence run in parallel with other workstreams during a busy deal process typically requires more resource.
Complexity of the target. A clean SaaS business with modern architecture and good documentation takes less time than a multi-product group with legacy systems, mixed cloud and on-premise infrastructure, and gaps in the data room. Complexity compounds cost at every step.
Access. Good access to technical management, clear data rooms, and responsive sellers reduce the time spent chasing information. Poor access adds time and cost, and is often a red flag in its own right.
Reporting requirements. A management summary and a set of findings has a different cost profile from a full written report designed for an investment committee or a lender. If you need the output in a specific format or for a specific audience, make that clear at the outset.
Buy-side vs sell-side: who pays and how the economics differ
In a standard buy-side mandate, the buyer commissions and funds the diligence. It's a deal cost, typically treated as part of the transaction expenses alongside legal and financial advisory fees. For PE and VC investors, technology DD is a standard line item. For corporate acquirers, it's increasingly expected by deal teams and boards.
In a sell-side mandate, the seller commissions a vendor due diligence report, either to share proactively with bidders or to use as the basis for a managed process. The seller funds this directly. A well-prepared vendor DD report can reduce the time and cost of a buyer's own diligence, which can accelerate the process and reduce price chipping late in negotiations.
Sell-side preparation work — helping a management team get their data room in order, identify gaps, and prepare for technical questions — is a separate category. This tends to be lighter in scope and lower in cost, but the return on investment is high if it prevents a bidder from walking away or reducing their offer.
Is it worth it?
Technology due diligence typically costs between 0.1% and 0.5% of deal value. For most transactions, that makes it one of the cheaper line items in the deal budget. The question isn't whether you can afford it — it's whether you can afford to skip it.
The most common post-deal surprises are technical ones: a code base that needs a full rewrite, a dependency on a single engineer who leaves, a security gap that surfaces in the first compliance audit, or infrastructure costs that bear no relationship to what was disclosed. Each of those was visible during diligence if someone looked.
Remediation costs are almost always higher than prevention costs. A code base rewrite post-acquisition can cost several times the original diligence fee. A security incident during the hold period can be an order of magnitude worse. The fee for a thorough technical assessment is usually small relative to what it protects against.
Even where the findings don't change the decision to proceed, they improve it. A buyer who understands the technical risk profile can structure the deal appropriately — through price, through warranties, through earnout mechanics, or through a realistic post-acquisition plan. That's not just risk management. It's deal craft.
How TechDD can help
TechDD provides technology due diligence for PE investors, VC funds, and corporate acquirers across a range of deal sizes and sectors. Work is scoped to the mandate — whether that's a pre-LOI review, a full mid-market assessment, or a vendor DD report prepared for a sale process.
Peter Rossi leads the practice. He has completed 22 acquisition integrations across five countries inside a PE-backed group, co-founded InfoSaaS and sold it to private equity in 2021, advised on £300m+ of PE and VC investment decisions, and spent four years at McLaren, including work on the Formula 1 programme. He brings operator experience to every engagement — not just a checklist.
If you're planning a transaction and want to understand what a technology review would involve and what it would cost, get in touch.
FAQ
How much does technology due diligence cost in the UK?
For most transactions, technology due diligence in the UK costs between £10,000 and £50,000, depending on deal size, scope, and complexity. Pre-LOI reviews can be completed for £5,000 to £10,000. Large or complex transactions can exceed £100,000.
Who pays for technology due diligence?
In most cases, the buyer pays. Technology DD is a standard deal cost for PE and VC investors. In some transactions, the seller commissions a vendor DD report to share with bidders, which the seller funds directly.
Can technology due diligence be done quickly?
A high-level review can be completed in one to two weeks. A full mid-market DD exercise typically takes three to five weeks. Compressing timelines is possible but usually carries a cost premium and may limit the depth of the assessment.
What is included in a technology due diligence report?
A typical report covers: architecture and infrastructure, team structure and key person risk, security posture, development practices, technical debt, and licensing. The scope varies by mandate. Some reports also include security testing, code review, or integration risk assessment.
How do I reduce the cost of technology due diligence?
Sellers can reduce the cost of a buyer's DD process by preparing well: maintaining documentation, having a clean data room ready, and being available for timely responses to queries. Buyers can reduce cost by having a clear scope, a realistic timeline, and selecting an adviser with relevant sector experience.