Before You Sign: A Practical Due Diligence Checklist for Vetting UK Suppliers

Supplier failure rarely announces itself in advance. From the customer's side, it tends to arrive as a sudden email about administration, a lapsed insurance policy, or an unfulfilled order at the worst possible moment. The disruption is not confined to the failed company; it cascades directly into the businesses that depended on it.

The remedy is unglamorous but effective: systematic due diligence before signing. For small and mid-sized UK firms, the following framework covers the essentials without requiring a compliance department to administer it.

Start with the Public Record

Companies House is free, searchable and underused. Before entering a significant supplier relationship, review:

• Filing history. Are accounts filed on time? Late or missing filings often signal internal disarray or cash flow distress. Note whether accounts are audited or have qualified opinions.
• Financial statements. Look beyond the headline profit figure. Examine liquidity (current assets against current liabilities), the level of director loans outstanding, and whether the company carries meaningful cash reserves or is precariously financed.
• Directors. Who are they, when were they appointed, and how frequently have they changed? High turnover at board level warrants questions.
• Charges and registrations. Outstanding charges against company assets indicate secured borrowing, which affects how the company might fare in a distressed scenario.

Alongside Companies House, a quick check of county court judgments and a review of the company's credit file — available at modest cost from the major credit reference agencies — will reveal payment behaviour that accounts alone cannot.

Read the Warning Signs in the Numbers

Financial red flags tend to follow familiar patterns. Be alert to:

• Persistent losses combined with shrinking working capital
• A reliance on short-term borrowing to fund day-to-day operations
• Significant intercompany balances or loans to connected entities
• A sudden change of auditors or accountants
• Requests for unusually large upfront payments or shorter payment terms than the market norm

None of these is automatically disqualifying. Collectively, they shape the questions you should ask — and how much concentration risk you are willing to accept.

Assess Key-Person and Concentration Risk

For many smaller suppliers, the business is effectively one or two individuals. That is not inherently a problem, but it changes the risk profile. Consider what happens if the principal leaves, falls ill, or exits the business. Is there a succession plan? Is the expertise documented, or does it live entirely in one person's head?

Equally, examine the dependency running in the other direction: how much of your operation relies on this single supplier? Where a supplier is critical, dual-sourcing or holding buffer stock may cost more per unit but is cheap insurance against operational paralysis.

Ask the Right Questions Before You Commit

Due diligence is partly documentary and partly conversational. Useful questions include:

• What professional indemnity and public liability insurance do you carry, and can you evidence it?
• What is your approach to subcontracting or outsourcing parts of the work?
• What are your business continuity arrangements if your systems or premises become unavailable?
• Can you provide references from clients of a similar size and sector?

The responses matter less for their content than for their specificity. Vague or defensive answers are themselves informative.

Build It into the Contract

Finally, embed the findings. Sensible contractual protections include service levels with remedies, audit or information rights, termination triggers tied to insolvency events or service failure, and — where appropriate — a requirement to notify you of material adverse changes in the supplier's financial position.

Due diligence cannot eliminate the risk that a supplier fails. What it does is ensure that when it happens, your business sees it coming, understands its exposure, and holds the contractual tools to respond. In supplier relationships, as elsewhere, the cheapest time to protect yourself is before you sign.