38% of M&A deals fail during due diligence. We analyse the most common findings, their impact on the final price, and how to prepare your business to get through the process with confidence.
The due diligence process in a business acquisition is, by most accounts, the single most consequential phase of any M&A transaction. European deal data consistently shows that between 35% and 40% of transactions that reach the due diligence stage never close. The reasons are rarely dramatic: most deals fall apart not because of fraud, but because sellers discover—alongside the buyer's advisors—realities they never fully knew about their own business.
This article takes a data-driven look at due diligence in practice: what buyers actually find, how findings shift prices, and which red flags tend to kill deals before the ink ever dries.
What due diligence really means in a business sale
Due diligence is the structured investigation a buyer conducts before committing to an acquisition. Its purpose is to verify that the business presented in the information memorandum matches the actual financial, legal, tax, and operational reality. But in practice, it is also one of the most powerful pricing tools a buyer has.
Every material finding becomes leverage. A contingent tax liability, an undocumented client contract, a key employee without a non-compete—each one translates into a price reduction request, an escrow holdback, or an additional representation in the sale and purchase agreement. Sellers who enter due diligence unprepared consistently leave money on the table.
The numbers behind due diligence outcomes
Looking at M&A market data across Europe's small and mid-cap SME segment:
- 38% of deals that enter due diligence do not close. Roughly half collapse due to findings the buyer considers unacceptable; the other half break down over the pricing gap the due diligence itself creates.
- 62% of deals that do close see a price adjustment during or after the process. The average adjustment ranges from 8% to 12% off the letter of intent price.
- Tax contingencies are the most common finding in SME acquisitions, appearing in over 70% of processes. Not all represent real risk, but buyers consistently put a value on them.
- Undocumented client contracts rank as the second most common friction point. In service businesses, more than half of revenue often rests on verbal agreements or auto-renewing contracts that were never properly formalized.
- Key-person dependency—typically the founder—is the qualitative factor that adds the most risk premium and most consistently suppresses the final price.
The five dimensions of a thorough due diligence
A complete due diligence covers five domains. In SME transactions, buyers decide how deeply to investigate each based on deal size and perceived risk.
Financial due diligence
The most time-intensive area. It scrutinizes three to five years of financial statements with focus on EBITDA quality—separating recurring from one-off items—working capital trends, actual debt (including implicit obligations such as operating leases, overdue payables, or informal shareholder loans), and customer concentration risk. A common finding: the adjusted EBITDA in the information memorandum can diverge 20–30% from the figure the due diligence team calculates once personal expenses are properly carved out.
Legal due diligence
Reviews the corporate structure, existing contracts (with customers, suppliers, employees, and landlords), intellectual property ownership, and ongoing or potential litigation. In SMEs, the most frequent issues are employment contracts with non-compliant terms and lease agreements containing transfer restrictions that complicate the transaction structure.
Tax due diligence
Analyses open tax years, VAT and corporate income tax returns, related-party transactions, and applied tax reliefs that may not transfer to a new owner. Undocumented intercompany pricing and overstated deductions are the two most common findings across SME acquisitions.
Commercial due diligence
The most qualitative domain. It assesses competitive positioning, client retention rates, revenue pipeline, and contract dependencies. Private equity buyers always commission this area; strategic buyers with direct sector knowledge may rely on their own judgment instead.
Operational and HR due diligence
Examines internal processes, systems, technology infrastructure, and staff structure. The central question: can the business run without the seller, and what will it take to retain the team that makes it work day to day?
What buyers actually find: most common issues in SME acquisitions
Based on deal experience across the Spanish and broader European SME market, the most recurring findings—ranked by pricing impact—are:
- EBITDA inflated by personal expenses: vehicles, personal travel, family salaries booked as business costs. These are often already partially known; the problem is the ones that weren't disclosed upfront.
- Unprovisioned tax contingencies: buyers respond with an R&W insurance requirement, a price holdback, or both.
- Implicit debt: deferred supplier payments, undisclosed shareholder loans, or material operating lease obligations. All are deducted directly from the equity price.
- Unformalized client contracts: buyers either require formalization before closing or discount a percentage of the price as client attrition risk following the ownership change.
- Key employees without non-compete agreements: the risk of the founder or a key commercial director leaving with the client base is always quantified and reflected in the price.
- Undisclosed litigation: even minor cases, if intentionally omitted, can trigger indemnification clauses in the final contract and create post-closing liability.
Realistic costs and timelines
For SMEs valued between €1M and €10M, advisory fees for a complete due diligence typically break down as follows:
- Financial DD: €8,000–€25,000
- Legal DD: €5,000–€20,000
- Tax DD: €4,000–€15,000
- Commercial DD (PE-led or larger deals): €20,000–€80,000
A complete due diligence process on a €2–8M transaction typically costs the buyer between €20,000 and €60,000 in advisory fees alone, plus legal costs for negotiating the sale and purchase agreement. Timeline: 4–10 weeks for SME-scale processes is the standard.
How to prepare your business for due diligence
The best due diligence outcome for a seller is one prepared well in advance. These steps make the most measurable difference:
- Organize corporate documents: minutes, deeds of incorporation, share register, and any amendments—all current and consistent.
- Formalize critical contracts: clients above 5% of revenue, key employees, strategic suppliers, and the property lease.
- Separate personal and business expenses clearly: buyers don't penalize historical mixing—they penalize the inability to explain it cleanly.
- Build a clean data room: organized by area (financial, legal, tax, HR, contracts). Disorganized data rooms slow the process and increase buyer suspicion.
- Consider a vendor due diligence: commissioning your own internal review before the sale process starts typically costs less than the price adjustment it prevents.
Red flags that kill deals
Not all findings are equal. Most are manageable with price adjustments or contractual protections. These are the ones that most often end negotiations entirely:
- Discrepancies between filed accounts and internal management accounts
- Ongoing tax inspections with undetermined outcomes
- High senior management turnover in the past two years
- Unexplained loss of a major client
- Unprotected intellectual property in technology or product-driven businesses
Frequently asked questions about due diligence in business acquisitions
Who pays for due diligence?
The buyer typically bears the full cost. In competitive processes, sellers sometimes commission a vendor due diligence (VDD) upfront and share it with all bidders, reducing total process costs and accelerating timelines for everyone involved.
Can the seller limit the due diligence scope?
Yes. It's common to defer commercial deep-dives and client interviews until the contract is in advanced negotiation, and to require enhanced NDAs before sharing competitively sensitive data with any prospective buyer.
What happens when findings emerge?
Most findings are resolved through price reductions, escrow arrangements, specific seller representations, or R&W insurance. Only the most serious—or those the seller cannot or will not remediate—lead to deal termination.
How long should due diligence take for an SME?
For businesses valued between €1M and €10M, a complete financial and legal process typically takes 4–8 weeks. Processes running beyond 10 weeks without clear justification often signal significant findings or poor document organization on the seller's side.
What is a virtual data room?
A secure cloud repository where the seller uploads required documents and the buyer accesses them in a controlled manner, with access logs tracking which documents each party has reviewed. Purpose-built platforms like Intralinks or Datasite are standard on larger deals; well-structured shared drives work for smaller SME transactions.
Does due diligence guarantee a safe acquisition?
No. It reduces risk; it does not eliminate it. Sophisticated fraud, future market risks, and post-closing surprises remain possible. That's precisely why the sale and purchase agreement always includes seller representations and warranties plus post-closing recourse mechanisms.
