Customer Concentration Risk: When One Client Is Too Much of Your Revenue

Your biggest customer is your best customer right up until the moment they are your only real customer. An IT services firm doing ₦8,000,000 a month with ₦3,200,000 of it from a single client does not have a great account. It has a dependency, and that dependency is quietly setting its payment terms, its collections policy, and its payroll risk.

Work out the number

Take the last twelve months of revenue, group it by customer, and divide your largest customer's total by the whole. That percentage is your customer concentration. Do it again for your top three combined.

There is no official threshold, but the practical reading is simple. Under 10 percent and no single customer can hurt you. Around 20 percent and you would feel their loss for a quarter. At 30 percent and above, they know they matter, and their finance team knows it too. Past 50 percent you are not really running a business with customers, you are running a department of theirs with worse job security.

Then run the same calculation on your receivables, which is the number most owners never look at. If one customer is 60 percent of everything currently outstanding, a single late payment is not a nuisance, it is your entire cash gap.

Concentration is what costs you your terms

The damage shows up first in negotiation, and it never looks like damage at the time.

They ask for Net 60 instead of Net 30. You want to say no, but they are 40 percent of the top line, so you say yes and tell yourself you will make it up on volume. Then they pay at day 75 anyway. You want to put them on credit hold, but pausing work on 40 percent of your revenue is not a real option, so you do not. You want to send a firm reminder, but the account manager is nervous about the relationship, so it goes out warm and gets ignored.

Every one of those is a normal commercial decision. Together they mean the customer, not you, decides your payment terms and decides whether your collections process applies to them. A business with ten customers at 10 percent each can enforce its terms because losing any one of them is survivable. That is the whole difference. Enforcing your terms takes very little courage when losing the customer would not hurt you, and a great deal of it when it would.

One late payment, no payroll

Take the same firm. Revenue ₦8,000,000 a month, ₦3,200,000 of it from the big account, salaries of ₦2,500,000 due on the last Friday. The client's parent company changes its payment run, and one month's invoice lands three weeks late.

You are profitable. You are also short ₦3,200,000 in the week payroll is due, and the other ₦4,800,000 is spread across customers who are on their own terms and not due yet. So you cover payroll from reserves, or from a loan, or from your own pocket. This is the profitable-but-broke trap, and concentration is what turns it from a bad month into an existential one, because there is no other customer big enough to fill the hole.

How to de-risk without firing your biggest customer

You almost never fix concentration by dropping the account. You fix it by making the account safer and making it smaller as a share of the whole.

1. Set a target and work the pipeline against it. No customer above 25 percent within twelve months. It is a sales goal, not a finance goal, so it belongs in the sales pipeline where someone owns it.
2. Tighten the terms on the big account, do not loosen them. The largest exposure should have the shortest terms, not the longest. It is the opposite of what usually happens.
3. Take deposits and bill in stages. A ₦3,200,000 monthly engagement with 30 percent up front is a very different risk from the same engagement billed in full in arrears.
4. Invoice more often, in smaller pieces. Monthly beats quarterly. Weekly beats monthly. You find out something is wrong sooner and less money is exposed when you do.
5. Set a credit limit per customer and enforce it. Decide the maximum you are willing to be owed by one account before work stops, write it down before you need it, and stick to it when the number is hit.
6. Hold a reserve sized to their biggest invoice. If you can survive them paying 60 days late, they stop being able to set your terms by accident.

Knowing your exposure before it bites

Most owners can name their biggest customer instantly and cannot tell you what share of their outstanding cash that customer is holding today. Arvalox tracks receivables by customer, so you can see concentration in your actual exposure rather than in last year's revenue, watch the balance on any one account against the limit you set, and get told when the account that matters most has started to drift late.