Customer concentration in a small business acquisition

A CIM's largest-customer percentage starts a question. It does not answer whether the customer will stay, how much profit depends on the account or who keeps the relationship working. A searcher needs to connect the customer schedule to the business they would actually own.

Buyers and lenders set their own concentration tolerances. There is no percentage in this guide that makes a deal acceptable or unacceptable. Your task is to establish the exposure, test what supports retention and decide what evidence you need before committing more time or capital.

Start with the CIM's definition

Record the period, revenue basis and customer grouping behind the headline figure. Does the schedule cover a full financial year, trailing months or year-to-date trading? Does it show invoiced sales, recognized revenue or cash receipts? Use the first-pass CIM checklist to preserve the seller's claim and its source before building your own view.

Request customer-level revenue for several completed years and the latest comparable period. Stable anonymized identifiers can support an initial screen while the seller controls disclosure of names. Ask for a mapping that stays consistent across exports. A renamed account should not appear to be a new customer.

Reconcile each period's customer total to the financial statements with the seller and your financial diligence provider. List credit notes, unallocated sales and timing differences separately. A neatly ranked list is not reliable if its denominator cannot be explained.

Build both revenue and gross-profit views

Create a schedule with one row per customer and columns for revenue, direct costs and gross profit in each period. Record the cost-allocation method. If the seller cannot produce customer-level costs, mark the profit view as incomplete and discuss what can be reconstructed with your QoE provider.

Calculate each account's share of total revenue and total gross profit for the same period. Review the largest accounts individually and together. Compare the latest period with the equivalent prior-year period so seasonal work does not look like unexplained growth or churn.

Gross profit needs interpretation. Check whether freight, subcontractors, discounts, returns and service labor are treated consistently. A highly profitable account may consume management time that is not allocated to it. Gross profit is not the cash available after overhead, debt payments and investment.

Keep a separate view of collections and overdue balances. A customer can contribute reported profit while absorbing cash through slow payment. Ask whether disputed invoices, rebates or service failures explain the balance.

Group accounts that share a decision-maker

Several billing names may depend on one parent company or procurement team. Preserve the individual accounts, then add a related-customer grouping with the evidence for each relationship. Ask who can approve purchases, renegotiate pricing or replace the supplier across locations.

Do not assume common ownership means every branch buys together. Equally, separate legal entities do not prove independent buying decisions. Investigate franchise networks, purchasing groups and referrals through a single channel where relevant. Keep confirmed common control separate from a suspected commercial dependency.

Work through the exposure

Synthetic example. All customers, figures and operating assumptions below are invented. The percentages illustrate arithmetic, not concentration limits.

A service business reports $2,000,000 in annual revenue and $800,000 in gross profit. The customer schedule reconciles to those totals. Alpha East and Alpha West have the same parent and a shared purchasing manager.

Customer	Revenue	Direct costs	Gross profit
Alpha East	$400,000	$200,000	$200,000
Alpha West	$200,000	$100,000	$100,000
Other customers combined	$1,400,000	$900,000	$500,000
Total	$2,000,000	$1,200,000	$800,000

Alpha East alone represents $400,000 ÷ $2,000,000 = 20% of revenue. The related Alpha group represents $600,000 ÷ $2,000,000 = 30% of revenue and $300,000 ÷ $800,000 = 37.5% of gross profit. Looking only at the largest billing account understates the shared exposure.

Assume the group leaves, all $300,000 of its direct costs disappear and overhead remains unchanged. Revenue falls to $1,400,000 and gross profit falls to $500,000. If annual overhead is $450,000, operating profit before interest and tax falls from $350,000 to $50,000. This simplified case assumes no replacement sales or transition costs.

The next diligence question is whether those direct costs really disappear when the work stops. Retained staff or committed subcontractor costs would make the outcome worse than this case. Compare the group's earlier-year revenue and margins, then ask what changed and whether the latest result is repeatable. The calculation identifies what to investigate; it does not predict a customer departure.

Read the contract and the relationship together

Request the signed agreements, amendments, purchase orders and relevant renewal correspondence for material accounts. Prepare a contract summary for counsel covering term, renewal, termination, pricing, volume commitments and service obligations. Ask counsel to assess assignment and change-of-control provisions against the proposed transaction structure, including whether any consent is needed. Do not infer transferability from a contract's end date.

Then map the people. Who won the account? Who handles complaints, negotiates prices and receives the customer's calls? Does anyone besides the seller have credibility with the buyer at the customer? BDC's acquisition diligence guide includes customer concentration and ownership of key relationships among the commercial questions to investigate.

Use the first owner call questions to explore the seller's role without treating a reassuring answer as proof. Arrange any customer contact through an agreed process with the seller and advisors. Record what interviews establish and what remains a management assertion.

Test tenure, churn and renewal evidence

For each material account, record the first sale, recent order history, next renewal or tender date and any known budget change. Long tenure deserves a follow-up question about why the customer stays. It does not settle whether the relationship will survive a change in ownership.

Track lost and shrinking accounts as well as new wins. Agree what counts as churn for this business: a project customer may buy irregularly, while a recurring-service customer has a clearer renewal cycle. Ask for explanations supported by order records or correspondence. Distinguish a completed project from dissatisfaction and a temporary pause from a confirmed loss.

Carry the findings into the deal and transition

Turn unresolved dependencies into named requests in the diligence checklist. Set a decision point for each material gap. A missing contract, an upcoming tender and an owner-only relationship require different evidence and different transition work.

Bring retention sensitivities into valuation discussions with your advisors and lender. Explain the earnings affected and the assumptions behind any price discussion rather than applying a mechanical concentration discount. An earnout or seller note with retention-linked terms may be an option to discuss with counsel, tax advisors and the lender, not a recommendation. Ask them about permitted structures, measurement disputes and financing constraints before proposing terms.

For the ownership plan, assign introductions, account responsibility and renewal follow-ups. Agree the seller's transition involvement and a process for monitoring service problems. Building additional customer relationships takes time; do not assume diversification will fund the first debt payment.

SearchWare's AI CIM screening helps review source evidence and prepare follow-up questions. Its Diligence Portal organizes requests and shared documents. Bring one deal's customer questions to a SearchWare trial, and review plans and availability.