Due diligence does not test whether a business is good — it tests whether the financial data proves it. The most common deal delays are caused by the seller’s inability to produce requested data, not by what the data shows. A buyer’s advisory team arrives with 200+ data request items spanning three years of monthly management accounts, customer-level revenue data, normalised EBITDA workings, and working capital analysis. Vendor due diligence preparation typically takes 3-6 months and can add 10-15% to deal value by reducing buyer uncertainty. A company with £2M EBITDA selling at 6x faces a £12M negotiation where a 10% discount driven by data uncertainty costs £1.2M — the standard outcome when sellers enter diligence unprepared. Both Deloitte and EY report that sell-side VDD processes significantly reduce deal timelines and improve price certainty. The minimum requirement is 12 months of clean, granular, consistent management accounts before the process begins.
A mid-market company enters a sale process. The owner expects the conversation to focus on growth potential, market position, and strategic fit. The buyer’s advisory team — typically a Big 4 or mid-tier accounting firm — arrives with a data request list running to 200+ items. They want three years of monthly management accounts, customer-level revenue data, contract details, normalised EBITDA workings, working capital analysis, and a clean trail from the accounting system to every number in the information memorandum.
This is where deals slow down, reprice, or collapse. Not because the business is weak, but because the data is not ready.
PwC estimates that data readiness issues are a contributing factor in the majority of mid-market deal delays. The information exists somewhere — in the accounting system, in spreadsheets, in the finance director’s head — but it is not organised, reconciled, or presentable in the form that due diligence requires.
What Due Diligence Actually Tests
Financial due diligence is not a re-audit. It is an investigation of the quality and sustainability of earnings, the normalised cost base, the cash conversion profile, and the key risks embedded in the financial structure.
Earnings quality. The buyer wants to understand what EBITDA would look like in their hands. This means stripping out owner-related costs, one-off items, related-party transactions at non-market rates, and any items that will not recur post-completion. Every adjustment needs supporting evidence. “The owner’s car costs £30K per year” needs the lease agreement, the allocation basis, and proof it is personal.
Revenue analysis. Not top-line growth. Granular breakdown by customer, product, geography, and contract type. Customer concentration, churn rates, contract renewal terms, and pricing trends. If your accounting system does not capture revenue at this level of detail, reconstructing it during a live deal process is expensive and unreliable.
Working capital. Monthly working capital balances for at least 24 months, with a clear understanding of what is “normal.” Seasonality, large one-off items, and intercompany balances must be identified and separated. The working capital mechanism in the sale agreement is one of the most disputed areas in mid-market deals — and the quality of data directly determines the outcome.
Net debt and debt-like items. Every liability, contingency, and off-balance-sheet commitment. Deferred revenue, provisions, pending claims, tax exposures. If it is not in the accounts, it will be in the data room — or it will be found and used against the seller’s price.
The Vendor Readiness Process
Smart sellers do not wait for a buyer to request data. They prepare a vendor due diligence (VDD) — a sell-side report that addresses the same questions a buyer would ask, produced on the seller’s timeline, under the seller’s control.
Deloitte and EY both report that VDD processes in the mid-market significantly reduce deal timelines and improve price certainty. The logic is straightforward: a buyer facing an information vacuum increases their risk premium. A buyer facing a clean, pre-analysed data set reduces it.
The preparation involves: cleaning up the chart of accounts so reporting is consistent across periods, preparing a normalised EBITDA bridge with documented adjustments, building customer and revenue analytics at the granularity buyers expect, preparing working capital analysis on a monthly basis, and assembling a data room with organised supporting documentation.
Common Readiness Failures
Inconsistent management accounts. The format changed three times in three years. Different cost classifications in different periods. No bridge between management accounts and statutory accounts. The buyer’s team spends weeks just making the data comparable.
Missing granularity. Revenue is captured at the invoice level but not tagged by customer segment, contract type, or product line. Rebuilding this from invoices during diligence is possible but slow, expensive, and prone to error.
Owner adjustments in the FD’s head. The FD knows that £50K in consulting costs was a one-off restructuring expense. But there is no documentation, no board minute, and no way for a buyer’s advisor to verify it. Undocumented adjustments get rejected.
What This Means for Mid-Market Companies
If a transaction is on the horizon — even a distant one — the preparation should start now. The minimum is 12 months of clean, granular, consistent management accounts before the process begins. Ideally, 24 to 36 months.
The cost of preparation is a fraction of the value at risk. A company with £2M EBITDA selling at 6x is negotiating a £12M price. A 10% discount driven by data uncertainty — because the buyer cannot verify revenue sustainability or normalised costs — is £1.2M. That is not a theoretical risk. It is the standard outcome when sellers enter diligence unprepared.