When One Contract Pays the Group: A Board Guide to Customer Concentration
Photo: Foreign, Commonwealth & Development Office, CC BY 2.0, via Wikimedia Commons
Customer concentration is one of the quietest risks in a UK group. It rarely appears as a single line in management accounts. Instead, it shows up as a subsidiary that has grown around one contract, a sales team that has learned one buying process, and a board pack that reports consolidated revenue without showing how much of it depends on a single customer. When that customer renegotiates, delays or leaves, the effect can move quickly from a sales problem to a covenant problem.
The distortion in the group picture
A group can look diversified at the top and be fragile underneath. One subsidiary may generate most of its revenue from a single retailer, contractor or public sector body, while other subsidiaries provide the balance. Consolidation smooths the picture. Shared services, cross-guarantees and management charges can then transmit the shock across the group. If the contract is lost, the subsidiary may still carry the same cost base, the same lease and the same people, while the group faces lower EBITDA and a tighter lending position. That is why customer concentration belongs in board reporting, not only in sales reviews.
Quantify exposure properly
The first step is to measure concentration at the right level. Group revenue by customer is useful, but it can hide the subsidiary view. Boards should see the top customer as a percentage of revenue and gross margin for each subsidiary, as well as for the group. They should also see receivables concentration, contract duration, renewal dates, termination rights, volume commitments and any price review mechanisms. A customer that represents 30% of group revenue may be 70% of one subsidiary. A contract with a long notice period is different from one that can be terminated for convenience at 30 days. The metric should be consistent, reported quarterly and explained when it moves.
Stress-test the covenants before the lender does
Concentration risk becomes urgent when it meets leverage. A useful board exercise is to model the loss of the largest contract under three scenarios: immediate termination, phased run-off over six to twelve months, and a price reset or volume reduction. For each scenario, show revenue, EBITDA, working capital, capital expenditure and covenant headroom. If the group has a leverage covenant, interest cover test or liquidity requirement, the board should see the headroom in pounds and months, not just a ratio. It should also review material adverse change clauses, concentration limits and any lender reporting obligations. Early dialogue with lenders is usually better than a surprise waiver request.
Protect the contract where possible
Contract protection is not a substitute for diversification, but it buys time. Groups should review notice periods, termination for convenience, change of control provisions, exclusivity, minimum volume commitments, service credits and transition assistance. Where the customer has significant bargaining power, the group may not win every point, but it should know which clauses matter. Auto-renewal traps and uncapped service credits deserve particular attention. Credit insurance or parent guarantees can help in some sectors, but they should be priced and disclosed rather than used to avoid the underlying issue.
Diversify with discipline
Diversification is easier to recommend than to deliver. A group with a dominant contract should not simply tell every subsidiary to sell more. It should identify adjacent customers, cross-sell services from other parts of the group and test new routes to market with proper investment appraisal. Sales incentives should reward margin and durability, not only revenue from the largest account. Targets should be specific: reduce the top customer to a stated percentage of subsidiary gross margin over a defined period, and report progress alongside the risk. Diversification has a cost, so the board should approve it as an investment rather than treat it as a sales aspiration.
Make it a standing board item
A concise concentration dashboard can sit alongside the usual financial pack. It should show the top customer by subsidiary and group, contract expiry profile, pipeline coverage, covenant headroom under the stress scenarios and progress on mitigation. The board should also discuss account succession: what happens if the relationship manager leaves, or if the customer changes procurement strategy? These are governance questions because they affect the reliability of the group plan. Customer concentration is not a reason to panic. It is a reason to measure, stress-test and negotiate before reliance becomes a governance problem.
