You’re several months from an exit you’ve been planning for years. Your corporate finance adviser has mentioned vendor due diligence. A colleague who sold recently says you probably only needed vendor assist. Your instinct is to ask what the difference is before committing to either.
That instinct is right. The two terms refer to different services, different price points, and different relationships with whoever ends up buying your business. Getting clear on the distinction before you brief an adviser is time and money well spent.
What’s the choice you’re actually facing?
Vendor assist and vendor due diligence are both sell-side advisory services, but they serve different purposes. Vendor assist focuses on getting you sale-ready: organising financial information, tightening accounting policies, preparing management for buyer questions, and fixing issues before they surface. Vendor due diligence produces a formal, independent report the buyer can legally rely on. The duty of care runs to the buyer, which is what makes it a materially different product.
Vendor assist (VA) is designed for the seller’s benefit only. The report or workplan belongs to you, and no duty of care is owed to the eventual buyer. VA is typically lighter, more flexible in scope, and less expensive than a full VDD engagement. The adviser’s job is to help you sort out what needs sorting before anyone looks, without forming an independent view buyers can rely on.
Vendor due diligence (VDD), by contrast, is commissioned by the seller but produced by an independent third party, usually a transaction services or corporate finance firm, to a standard that allows the finished report to be shared with potential buyers. In a competitive process, the successful buyer may formally receive the report with an agreed duty of care. Mercer & Hole notes that VDD can give sellers more control over process timing, reduce business disruption, and surface value-critical issues before going to market.
When does vendor assist make the better choice?
Vendor assist works best when your buyer universe is small and well-defined, typically a trade buyer or strategic partner who already knows your sector. If you’re expecting one or two realistic acquirers, each of whom will run their own due diligence anyway, a formal VDD report adds cost without reducing buyer effort. VA lets you fix visible weaknesses and tighten your financial narrative before anyone sees them.
VA is also worth considering when the business has untidy corners that need sorting before a formal review would expose them. Saffery describe vendor assistance as a dry run of due diligence, giving owners a clear list of improvements and the time to address them. Moore Kingston Smith positions it as a flexible alternative to VDD, tailored to management bandwidth and cost constraints. Henderson Loggie note it is particularly suited where the vendor needs help preparing for sale rather than producing a report for buyer reliance.
For owner-managed service firms, a VA engagement can also be the right place to build out data governance artefacts: records of processing activities, data protection impact assessments, and model inventories if AI is in use. The ICO’s guidance on data sharing in mergers and acquisitions makes clear that sellers must consider how personal data is handled during a transaction. Having that documentation ready before the first buyer conversation reduces a common source of late-stage concern.
When does vendor due diligence make sense?
Vendor due diligence suits competitive, multi-bidder processes, particularly where private equity is in the room. When three or more parties are running parallel interest, a single independent report reduces duplication: rather than each bidder commissioning their own financial review, they receive the VDD report you have already commissioned. Price Bailey notes that addressing issues early through this approach can shorten the process, reduce management disruption, and support a stronger final valuation.
VDD also makes sense when you want to control the information narrative in an auction. A well-prepared report means issues enter the process on your terms rather than each bidder uncovering them independently and reaching different conclusions. Mercer & Hole notes that vendor-initiated due diligence allows early identification of issues that can be resolved before going to market, which is a meaningful advantage in a competitive process.
In UK practice, the successful buyer in a structured process often pays for the right to rely on the VDD report. Smith & Williamson, now part of Evelyn Partners, explains that VDD reports are initially addressed to the seller but can be released to a defined buyer group with an agreed duty of care, reducing the need for each bidder to run a full independent financial review. For regulated service firms, the FCA’s operational resilience framework has added another standard component to buy-side questionnaires: evidence that important business services and their dependencies have been mapped, with a compliance deadline that passed in March 2022.
What does it cost to get the call wrong?
Choose VA when your process is a competitive PE auction and bidders will still commission full buy-side due diligence regardless. That means duplicated questions, repeated management presentations, and an extended timetable while your business still has to trade. Commission full VDD for a bilateral trade sale to a single known buyer and you may spend tens of thousands on a report the buyer’s own advisers will largely replicate anyway.
UK mid-market advisers indicate that VA fees typically run to the low-to-mid five figures, while full VDD can reach mid-to-high five figures, occasionally into the low six figures on complex deals. Those figures are indicative and vary by transaction size and complexity, but the cost differential is real. Pay more than you need to and you’ve consumed advisory budget that could have gone on legal fees or management preparation. Pay less and you’ve handed buyers an information asymmetry.
There is a timing risk alongside the cost one. Price Bailey cautions that undertaking sell-side diligence too late limits your ability to address issues before buyers discover them, raising the risk of late-stage price reductions or a process that collapses. VA started early gives you time to fix what is fixable. VDD commissioned too close to market produces a formal document of issues you no longer have time to resolve.
The data and cyber angle adds a further layer. The ICO fined British Airways £20m in 2020 for security failings affecting around 400,000 customers’ data, and fined Marriott International £18.4m for weaknesses that pre-dated an acquisition and continued post-deal. These cases now appear in buyer diligence questionnaires as precedents. The NCSC’s guidance on cyber security in M&A urges both parties to identify and address cyber risks early, specifically to avoid late discoveries that derail negotiations.
What should you ask before you decide?
Before briefing any adviser, answer a few practical questions. How many realistic buyers are there? If it’s above three, and especially if private equity has expressed interest, VDD is worth the cost. Are your management accounts and forecasts in good shape? If not, VA-style preparation may deliver more value than a formal report built on unreliable numbers. What is your data and AI exposure?
On data and AI specifically, if your service firm uses AI to analyse customer data or operates in financial services, health, or education, buyers will routinely ask for documentation of your data governance arrangements. The ICO’s guidance on AI and data protection, along with its automated decision-making guidance, sets out what responsible operators are expected to have in place. If you sell into EU markets and any AI systems could fall under the high-risk categories in the EU AI Act, buyers with EU exposure will expect compliance evidence. Maximum fines under the Act can reach €35m or 7% of global annual turnover for serious non-compliance, and acquirers are beginning to build that risk into valuations.
On management bandwidth: VA is often used precisely to reduce the drain on leadership time by pre-empting buyer questions before they arrive. If your team cannot absorb months of Q&A without harming trading, that practical argument alone may make VA the right starting point, even if a more formal process follows.
Neither route is universally right. The best advisers will clarify which structure fits your deal before you commit to anything. If yours hasn’t raised the distinction unprompted, it’s a question worth asking early.
