Customer Concentration: When One Client Is a Risk to the Business

Customer concentration is the share of revenue that comes from your largest customers. When one customer accounts for a large part of sales, the business’s profit, cash flow and bargaining position all depend on a relationship it does not control. Losing that customer, or having them delay payments or demand lower prices, can turn a profitable business into a loss-making one within a single quarter.

Concentration is not automatically bad. Many good small businesses start with one anchor client. The risk is in not measuring it and not planning for what would happen if it changed.

Measuring it

Three figures from last year’s sales ledger are enough:

• Largest customer’s share of revenue.
• Top three customers’ share.
• Top ten customers’ share.

Compute them on revenue and, separately, on receivables outstanding at year-end. A customer can be 20% of sales and 40% of the money owed to you if they pay more slowly than everyone else.

There is no official threshold. A practical working rule is to start planning for the risk once one customer passes about a fifth of revenue, or the top three pass half, and to test what losing the largest one would do, which is the next step.

What losing the largest customer would do

A packaging business:

The largest customer provides 45% of revenue. Without it, contribution falls by ₹31.5 lakh while fixed costs stay the same, and a ₹20 lakh profit becomes an ₹11.5 lakh loss.

Fixed costs do not fall immediately when a customer leaves. Staff, rent and equipment were sized for the larger business. Even if some costs can be cut, there is usually a period of months in which the business carries costs built for revenue it no longer has.

Assumes the same contribution margin on the remaining customers and no reduction in fixed costs. In practice, a large customer often buys at a lower margin, which softens the fall in contribution, but it also usually takes up capacity and staff time that do not disappear with it.

The quieter risks

Outright loss is the obvious risk. Three others are more common.

Pricing pressure. A customer who knows it is 45% of your business knows you cannot easily walk away. Annual price negotiations tend to go one way.

Payment terms. The same leverage stretches payment terms. When the largest customer moves from 45 to 90 days, the effect on cash is immediate and large, and is felt across the whole business.

Dependence on one contact. Many concentrated relationships rest on one buyer or manager. When that person moves on, the relationship can change overnight, whatever the contract says.

How lenders and buyers see it

Banks assessing a working capital limit look at receivables quality, and a large share owed by one debtor is a concentration of credit risk. Anyone considering buying or investing in the business will discount its value for concentration, because the future profit is less certain. Reducing concentration before either conversation strengthens the business’s position in both.

Reducing the exposure

1. Set a target and track it. For example, no customer above 25% of revenue within two years. What is measured quarterly tends to move.
2. Grow the next tier deliberately. Give sales effort and capacity to the customers ranked two to ten, not only to the anchor.
3. Widen the relationship with the large customer. Contacts in more than one department or site make the relationship less dependent on a single person.
4. Protect the contract. Notice periods, minimum volumes or a gradual exit clause buy time to replace revenue if the relationship ends.
5. Keep costs flexible. Where possible, use contract labour or outsourced capacity for the work that serves the largest customer, so costs can fall if volumes do.
6. Hold a larger reserve. A concentrated business needs more cash buffer than a diversified one of the same size.

Checking your own position

Concentration can also sit on the supply side. A business that buys a critical input from one supplier, or sells mainly through one marketplace or one distributor, carries the same kind of dependence. The same test applies: what happens to profit and cash if that relationship changes its terms or ends?

Take last year’s revenue by customer, sort it, and compute the three shares. Then run the table above for your own business: remove the largest customer, keep fixed costs where they are, and see what happens to profit and cash. If the answer is a loss, you know how much new revenue the business needs from others, and roughly how long you would have to find it.

Where this fits

• The contribution behind the calculation: contribution margin and pricing decisions
• When a large customer pays late: what to do when a customer is not paying
• The buffer a concentrated business needs: how much cash reserve to hold
• Tools: revenue and profit converter · break-even calculator