What Happens During Due Diligence When Selling a UK Business?

Due diligence begins the moment Heads of Terms are signed and typically runs for four to eight weeks — longer if your records are disorganised or the buyer's team is slow. As the seller, you are no longer pitching. You are being scrutinised. The buyer's accountants, lawyers, and tax advisers will examine everything you told them during the deal process and test whether it holds up. How well you handle this period has a direct bearing on whether the deal completes — and at what price.

Table of Contents

What is the data room and what goes in it?

A data room is a secure, organised digital repository — usually hosted on a platform such as Datasite, Intralinks, or a simpler equivalent — where you upload documents for the buyer's advisers to review. Think of it as the single source of truth for your business: everything the buyer needs to verify the deal is in there.

Setting it up properly before DD formally begins saves significant time and signals to the buyer that you run a tight ship. A poorly organised data room — incomplete, badly labelled, with obvious gaps — tells the buyer something about your business before they have read a single document.

What typically goes into the data room:

  • Corporate documents: Certificate of incorporation, articles of association, shareholder agreements, board minutes, Companies House filings, any historic share issuances or restructuring
  • Financial records: Three to five years of statutory accounts, management accounts, aged debtor and creditor reports, bank statements, loan agreements, hire purchase and leasing schedules
  • Contracts: Key customer contracts, supplier agreements, any long-term commitments, exclusivity arrangements, and any contracts with change of control clauses
  • HR and employment: Contracts for all employees (especially senior management), details of any ongoing disciplinary matters, pension arrangements, details of any TUPE obligations from past transactions
  • Property: Leases, title deeds, rent review schedules, any dilapidations issues or environmental surveys
  • Intellectual property: Trade mark registrations, patents, software licences, website and domain ownership
  • Litigation and regulatory: Any current or historic litigation, HMRC correspondence, regulatory licences, sector-specific compliance records
  • Insurance: Current policies and claims history

The more complete and well-labelled your data room, the faster DD moves.

What are the four main DD workstreams?

Financial due diligence

This is usually the most intensive workstream. The buyer's accountants — typically a mid-tier or Big Four firm depending on deal size — are looking at the quality of your earnings, not simply the headline profit figure.

Their focus will be on:

  • EBITDA quality: Are your profits repeatable and sustainable? They will strip out one-off items, director remuneration above a market rate, personal expenses run through the business, and any revenues that are unlikely to recur.
  • Working capital: What is the normalised level of debtors, creditors, and stock needed to run the business day-to-day? This feeds directly into the locked-box or completion accounts mechanism in the deal.
  • Cash generation: How well does EBITDA convert into actual cash? Businesses with slow-paying customers or high stock levels may show good profits but poor cash conversion.
  • Capex requirements: Is the business under-invested? Are there asset replacement costs on the horizon that the buyer will bear?

Commercial due diligence

Commercial DD may be conducted by the buyer's corporate finance team or an external consultant. They are asking: does this business have a defensible market position, and will it continue to grow after the sale?

Key areas of focus:

  • Customer concentration (if your top three customers represent 60% of revenue, that is a risk)
  • Quality and length of customer contracts
  • Competitive dynamics — who else is in your market and why do customers choose you?
  • Pipeline and forward order book
  • Revenue visibility and recurring income

The buyer's solicitors will review the data room for anything that could create liability for the buyer post-completion. They are particularly focused on:

  • Corporate structure and share ownership — is the legal title to the business clean?
  • Employment contracts and any disputes
  • Property — title, lease terms, any issues that could affect the buyer's use of the premises
  • Intellectual property ownership — is the IP properly registered and owned by the company, not an individual?
  • Contractual change of control clauses — do any key contracts allow the counterparty to terminate on a change of ownership?
  • Regulatory compliance — are all licences and permits current and transferable?

Tax due diligence

Tax DD is often underestimated by sellers. The buyer's tax advisers will look at:

  • HMRC compliance — are VAT returns, PAYE, and corporation tax filings up to date and accurate?
  • Any historic liabilities — unpaid tax, penalties, open HMRC enquiries
  • R&D tax credit claims — are they robust and well-documented?
  • The proposed transaction structure from a tax perspective — share sale versus asset sale, treatment of deferred consideration, earn-out mechanics

This article contains general information only and does not constitute financial or tax advice. Every business sale is different. Speak to a qualified UK tax adviser about your specific situation before making any decisions.

What does a typical DD timeline look like?

StageTypical TimingKey Activity
HoTs signedWeek 0Legal exclusivity begins; data room access granted
Initial data room reviewWeeks 1–2Buyer's advisers identify gaps; Q&A list issued
Management presentationsWeeks 2–3Face-to-face or video sessions with buyer's DD teams
Q&A roundsWeeks 2–6Seller responds to queries; additional documents uploaded
Draft SPA issuedWeeks 4–6Legal negotiations begin in parallel
DD reports issued to buyerWeeks 6–8Buyer's advisers present findings; deal risks identified
CompletionWeeks 8–14SPA signed; funds transferred

Well-prepared businesses with clean records routinely complete DD in four to six weeks. Poorly prepared ones can drag on for three to four months — by which point deal fatigue sets in and buyers start looking for reasons to renegotiate.

What causes delays in due diligence?

The most common causes of delay are within the seller's control:

  1. Incomplete data room at the outset — buyers issue a Q&A list and wait weeks for responses
  2. Inconsistencies between management accounts and statutory accounts — both need to be explainable
  3. Missing contracts — particularly customer agreements that were never formalised in writing
  4. HR issues — employment contracts that do not reflect actual terms, or employees on informal arrangements
  5. Outstanding HMRC matters — any open enquiry will cause the buyer's tax team to pause
  6. Property issues — leases with personal guarantees from the current owner, or properties held in a related entity rather than the trading company
  7. Change of control clauses — particularly in public sector contracts, NHS frameworks, or large corporate supply agreements

The single best thing you can do to accelerate DD is to prepare your data room thoroughly before HoTs are signed — not after.

What red flags come up most frequently?

In UK mid-market deals, these are the issues that most commonly cause a buyer to pause, reprice, or walk away:

  • Customer concentration — one or two customers representing a disproportionate share of revenue
  • Revenue that is informal rather than contracted — long-standing customers with no written agreement
  • Key-person dependency — if the business cannot function without the owner, the buyer has a problem
  • Undisclosed or informal remuneration — expenses, benefits, or family salaries that inflate true EBITDA when normalised
  • Litigation or regulatory action — even historic claims that were settled can raise questions
  • Environmental liability — particularly for manufacturing, construction, or waste management businesses
  • Pension deficit — defined benefit schemes can be a significant liability

None of these are necessarily deal-killers, but they will all be reflected in the buyer's valuation — and in their warranty and indemnity requirements.

What is price-chipping and how do you resist it?

Price-chipping is the practice of a buyer using findings from DD to justify a reduction in the agreed headline price. It is common. Not all of it is dishonest — some findings genuinely do change the risk profile of the deal. But some buyers use DD as a negotiating tool, raising minor issues to pressure the seller into concessions.

How to resist it:

  1. Prepare thoroughly before HoTs — a buyer who finds no surprises in DD has no credible basis for chipping
  2. Disclose known issues early — surprises discovered mid-DD give the buyer leverage; issues disclosed upfront do not
  3. Quantify any agreed adjustments carefully — if a customer has recently left, agree how the revenue impact is calculated before accepting a price reduction
  4. Keep your advisers close — your corporate finance adviser should be monitoring the buyer's DD process and pushing back on unjustified claims
  5. Know your alternatives — a buyer who knows you have no other options will be more aggressive; wherever possible, preserve competitive tension through the process

Before entering DD, it helps to understand what buyers are genuinely looking for beneath the financials — see What Buyers Look for in Due Diligence for a detailed breakdown. If you are not yet at the HoTs stage, Heads of Terms Explained covers what should and should not be agreed before you grant exclusivity.

FAQ

How long does due diligence take in a UK business sale? For a well-prepared business, four to six weeks is realistic. If records are incomplete or issues arise, eight to twelve weeks is common. Larger or more complex businesses can take longer still.

Do I have to provide everything in the data room upfront? No — buyers typically issue a document request list at the start and you respond in rounds. But uploading as much as possible at the outset speeds the process considerably and reduces the number of Q&A rounds.

What happens if the buyer finds something they were not told about? It depends on the materiality and timing of the discovery. At best, they will request an explanation. At worst, they will use it to reduce the price or seek a specific indemnity in the SPA. Deliberate non-disclosure of material issues can give the buyer grounds to rescind the deal.

Can I conduct my own due diligence on the buyer? Yes, and you should — particularly if any part of the consideration is deferred, structured as an earn-out, or dependent on the buyer's future financial performance. Understanding who you are selling to matters.

What is a management presentation in DD? It is a structured session — usually one to three hours — where your management team presents the business to the buyer's DD advisers. It covers strategy, operations, financials, and key risks. Being well-prepared for this session materially affects the buyer's confidence in the business.

What is a warranty and indemnity in the context of DD? Warranties are statements of fact about the business that you give in the SPA. If they turn out to be untrue, the buyer may have a claim against you. Indemnities are specific protections for known risks identified during DD. The scope and breadth of these are directly influenced by what the buyer finds in DD — which is another reason clean DD matters.

Use the free valuation calculator on the Succession Group website to get an indicative range for your business based on sector, revenue, and EBITDA. It takes under five minutes and gives you a realistic starting point before you enter any formal process.