Why most small business sales fail at due diligence — and how to avoid it

Industry data consistently shows that a significant proportion of agreed business sales are either withdrawn, renegotiated, or significantly reduced in price during due diligence. For small business transactions, the rate is even higher than in larger deals — primarily because sellers have had less exposure to the process.

Here are the most common reasons deals fail or get renegotiated at DD stage:

Financial restatement surprises: When a buyer's accountant restates the P&L and finds EBITDA is significantly lower than presented, the entire deal economics change. This happens frequently when sellers haven't proactively normalised their financials. The fix: do it yourself, first.

Customer concentration: A buyer discovers that 40% of revenue comes from one customer with a rolling 30-day contract. Suddenly the business looks very different. If you have concentration risk, address it before sale — either by growing other customers or by securing longer contracts with key accounts.

Key person dependency: The buyer's team meets the management team and realises the founder is doing five people's jobs. No buyer wants to acquire a business that's entirely dependent on the seller staying. This is the most common structural issue in small business sales.

Undisclosed liabilities: Pending litigation, HMRC disputes, personal guarantees, director loans — these emerge during legal DD and create deal uncertainty. Full disclosure early is always better than discovery late.

IT and data issues: Increasingly common. A cybersecurity review reveals inadequate data protection practices, or a systems audit finds that key business data is stored on personal devices. Buyers have become more sophisticated about this.

The pattern across all of these is the same: the issue existed before the sale process started, wasn't addressed, and then became a negotiating tool for the buyer. The solution is always the same too — identify and address issues before going to market, ideally 12–24 months in advance.