How long does due diligence typically take?

For UK SME transactions, due diligence typically takes 4-8 weeks. The duration depends on the complexity of the business, the number of workstreams (financial, legal, commercial, tax, operational), and how well-prepared the seller is. A well-organised data room and responsive management team can significantly shorten the process.

Who pays for due diligence?

Each party pays for their own advisors. The buyer pays their accountants, lawyers, and any specialist consultants conducting the investigation. The seller pays for their own legal and accounting advisors who support the process, prepare the data room, and respond to queries. Total seller-side DD costs typically range from £15,000 to £50,000 depending on deal size and complexity.

Can due diligence kill a deal?

Yes. Material findings during due diligence — such as undisclosed liabilities, financial irregularities, regulatory breaches, or customer concentration risks — can cause buyers to withdraw or significantly renegotiate the price. This is why proactive preparation and honest disclosure are so important. Surprises during DD are the single biggest cause of deal failure.

What if the buyer uses due diligence to renegotiate the price?

This is common and should be anticipated. Some buyers use DD findings — however minor — as leverage to reduce the price. A good advisor will help you distinguish between legitimate concerns requiring adjustment and opportunistic renegotiation tactics. Having competitive tension (multiple interested buyers) is the most effective defence against price-chipping during DD.

Should I do vendor due diligence before going to market?

Vendor due diligence (VDD) — where the seller commissions their own DD report before approaching buyers — is increasingly popular for larger transactions. It identifies and addresses issues before they become buyer concerns, accelerates the process, and demonstrates professionalism. For businesses valued above £5 million, VDD is often a worthwhile investment. For smaller transactions, thorough internal preparation achieves a similar effect at lower cost.

How to Handle Due Diligence as a Seller

What Due Diligence Means for Sellers

Due diligence is the buyer's investigation into your business — a systematic examination of financial, legal, commercial, and operational information to verify that what you've represented is accurate and to identify any risks. For sellers, it's often the most stressful phase of the M&A process: intrusive, time-consuming, and occasionally uncomfortable.

However, well-prepared sellers not only survive due diligence — they use it to strengthen their negotiating position. A clean, well-organised due diligence process signals to the buyer that the business is professionally managed, which reinforces confidence and protects valuation.

Preparing for Due Diligence

Setting Up Your Data Room

A virtual data room (VDR) is the standard platform for sharing due diligence documents securely. Popular providers include Datasite, Ansarada, and iDeals, though simpler solutions can work for smaller transactions. Your data room should be:

Well-organised: Use a clear folder structure following standard due diligence categories (financial, legal, tax, commercial, operational, HR, IT, property).
Access-controlled: Grant different access levels to different parties. The buyer's lead advisor may see everything, while specialist consultants should only access their relevant sections.
Watermarked: Apply dynamic watermarks showing the recipient's name on every document to deter unauthorised sharing.
Activity-tracked: Monitor who is viewing which documents and how often — this provides valuable intelligence about buyer priorities and concerns.

Pre-Due Diligence Housekeeping

Before opening the data room, conduct your own internal review. Address issues proactively rather than having buyers discover them:

Ensure all company filings are up to date (Companies House, HMRC, regulatory bodies)
Resolve any outstanding director loan accounts
Confirm all key contracts are signed and filed (not just operating on verbal agreements)
Update the statutory registers and company minute books
Review employment contracts for consistency and completeness
Obtain any missing third-party consents or waivers

Common Due Diligence Requests

Financial Due Diligence

Financial DD is typically the most intensive workstream. Expect requests for:

3-5 years of statutory accounts and management accounts
Monthly management accounts for the current year and prior year
Detailed revenue analysis by customer, product, and geography
Gross margin analysis and cost breakdowns
Working capital analysis and cash flow forecasts
Details of any related-party transactions or owner benefits
Tax returns and correspondence with HMRC
Debtor and creditor ageing schedules

The buyer's accountants will probe for quality of earnings — distinguishing between sustainable, recurring profits and one-off or unsustainable elements. Being transparent about add-backs and normalisations from the outset builds trust and avoids adversarial negotiations later. Our valuation guide explains how earnings quality affects multiples.

Legal Due Diligence

Legal DD covers the company's constitutional documents, contracts, litigation history, intellectual property, regulatory compliance, and property arrangements. Common requests include:

Articles of association and shareholder agreements
Material contracts (customer, supplier, partnership agreements)
Employment contracts and staff handbook
IP registrations and licence agreements
Property leases and title documents
Insurance policies and claims history
Details of any current or threatened litigation

Commercial Due Diligence

Commercial DD examines the market dynamics, competitive positioning, and sustainability of the business's revenue streams. Buyers may request:

Market analysis and competitive landscape overview
Customer concentration analysis and contract renewal pipeline
Sales pipeline and forward order book
Pricing strategy and discount history
Customer satisfaction data and churn rates

Managing Red Flags and Difficult Questions

Every business has imperfections. The key is how you handle them. Attempting to hide issues is almost always counterproductive — experienced DD teams will find them, and the discovery will damage trust far more than the issue itself.

Better strategies include:

Disclose proactively: If you know there's a skeleton in the cupboard, raise it early with context and mitigation. "We had a customer dispute in 2024 which was resolved through mediation — here's the documentation" is far better than having the buyer discover it in your email archives.
Provide context: Raw data without context invites the worst interpretation. Accompany sensitive disclosures with explanatory notes that provide the full picture.
Demonstrate remediation: Where issues have been identified and fixed, show the evidence. A problem that's been resolved demonstrates management capability; one that's been hidden suggests the opposite.
Be responsive: Slow responses to DD queries create suspicion and frustration. Set internal targets for response times (48-72 hours maximum) and assign clear responsibility for each workstream.

Maintaining Deal Momentum

Due diligence is where many deals lose momentum — or die entirely. The process is inherently negative (it's designed to find problems), and without active management, it can create a spiral of queries, concerns, and renegotiation attempts.

To maintain momentum:

Set a clear timeline: Agree a DD schedule with the buyer upfront, with defined milestones and a target completion date. Open-ended processes drift.
Manage query flow: Channel all DD requests through your advisor rather than allowing direct contact between the buyer's team and your staff. This maintains control and prevents inconsistent or incomplete responses.
Keep running the business: The biggest risk during DD is that the seller becomes so consumed by the process that the business suffers. Delegate DD responsibilities where possible and maintain your focus on trading performance — nothing kills a deal faster than deteriorating results during the sale process.
Stay commercially focused: Not every DD finding requires a price adjustment. Work with your advisor to distinguish between genuine issues and negotiating tactics, and respond accordingly.

At VAMOS, managing the due diligence process is one of our core responsibilities. We act as a buffer between you and the buyer's DD team, ensuring queries are handled efficiently, sensitive issues are managed carefully, and deal momentum is maintained throughout.