Most commentary on commercial due diligence is written with large-cap private equity in mind: hundred-page market studies, commissioned surveys, dedicated teams. For buyers operating at sub-£50 million deal values, that model is neither practical nor proportionate. What matters is a focused, senior-led review that tests whether the commercial assumptions in the business case are supportable. This guide covers what commercial due diligence actually checks at the lower end of the market, where the common mistakes sit, and what founders and operators on both sides of a deal should prepare.
What commercial due diligence is actually checking
Commercial due diligence is not a market-sizing exercise. At its core, it is an assessment of whether the target business holds a defensible position that will survive under new ownership. That breaks into three practical questions. First, is the revenue base as stable as the information memorandum suggests? Second, is the competitive position strong enough to sustain margins over the investment horizon? Third, are the growth assumptions realistic given how the market actually behaves?
In a lower-mid-market context, the answers come primarily from customer and competitor analysis, not from desk research or published reports. Speaking directly with customers, lapsed customers, and market participants who have a reason to know the target's standing is where the meaningful signal sits. Report-based analysis has its place, but it cannot substitute for primary work when the business is largely invisible in aggregate data.
The information memorandum is a starting point, not a source
Sellers present their businesses well. That is reasonable and expected. The information memorandum will typically show a coherent market narrative, a customer list that appears diversified, a pipeline that looks healthy, and revenue trends that support the valuation. Commercial due diligence begins by treating each of those claims as a hypothesis to test, not a fact to accept.
Customer concentration is the single issue most frequently understated in lower-mid-market transactions. A business with eight listed customers may derive the majority of its recurring revenue from two of them. Both may be on contracts with break clauses, or with individuals rather than procurement departments, meaning the relationship does not automatically transfer. Understanding the true concentration, the contract terms, and the relationship structure is foundational work that no amount of management presentation replaces.
Similarly, stated pipeline figures are only as reliable as the CRM discipline behind them. A pipeline of named opportunities is worth examining closely: stage definitions, age of entries, whether lost deals are accurately marked, and whether the conversion assumptions in the forecast are consistent with historical close rates. Weak pipeline hygiene is not disqualifying, but it changes how much weight the revenue growth case can carry.
Competitive position at subscale
Lower-mid-market businesses rarely operate in markets with a cleanly defined competitive set. They often compete against regional independents, specialist boutiques, and larger players who treat the segment as secondary. Commercial due diligence has to map the real competitive dynamics rather than accepting the simplified version presented in a deck slide.
The critical distinction is whether the competitive advantage is structural, such as a proprietary process, a long-term contract, or a genuine switching cost, or whether it is personal, resting on a founder relationship that may not transfer. Primary research conducted independently of management is the most reliable route to an honest answer. Customers who have switched away, or who were approached and chose a competitor, often provide clearer signal than those still on the books and carefully managed through the sale process.
Where buyers go wrong
The most common mistake is starting commercial diligence too late. Commercial work should begin alongside financial due diligence, because the commercial findings inform how the financial assumptions need to be stress-tested. A revenue forecast that looks reasonable on paper may carry a different risk profile once the customer concentration picture is clear.
A second mistake is relying entirely on management interviews. Management teams in owner-managed businesses are, almost by definition, optimistic about their own commercial position; primary research with customers and competitors needs to sit alongside those conversations, not replace them. A third mistake, common among first-time acquirers, is treating commercial diligence as a box to tick rather than as the primary input to price and structure. If the findings reveal genuine concentration risk or a competitive position more fragile than presented, that has direct implications for how the deal is priced and whether earn-out mechanisms are appropriate.
What sellers and targets should prepare
If you are a founder or operator preparing for a sale process, the commercial section of your data room will receive close scrutiny. Buyers focus on customer contracts (particularly renewal terms and break provisions), sales history at customer level over at least three years, and documented evidence of competitive wins and losses. An honest account of where concentration risk sits builds more credibility with serious buyers than a data room that appears to obscure it.
Reference-ability matters. Buyers will want to speak with customers directly, and having two or three customers who are willing to take a call is worth more in credibility terms than any number of testimonial quotes in a document.
Scope and timing at the lower end of the market
For a deal in the £5 million to £50 million range, a well-scoped commercial due diligence programme can be completed in four to six weeks, led by a senior practitioner with direct sector knowledge rather than delegated to analysts working from a standardised template. The output is a structured view on the sustainability of the revenue base, the strength of the competitive position, and the credibility of the growth case, with a clear statement of what the diligence did and did not test. That is the document that supports the investment committee or the bank, and it should be written with that audience in mind.
If you are preparing for an acquisition or a sale process and want a direct conversation about how commercial due diligence should be scoped for your transaction, book a consultation with the Blash Advisory team.
