A businessman I will call Mr Moyo had landed the account every supplier wants.
A large corporate had moved most of its monthly orders to his company. The sales team celebrated. Mr Moyo hired more people, bought stock specifically for that account and stopped hunting as hard for new business.
Then the corporate delayed payment.
That is customer concentration risk. One large customer can look like growth on a spreadsheet while quietly becoming the one thing keeping your payroll, rent and tax payments alive.
Big customers are good.
Depending on one is dangerous.
Challenge: When One Customer Becomes the Business
Mr Moyo’s biggest account brought in about 45% of revenue. The business knew the revenue figure, but nobody had checked how much gross margin came from that customer, how old its unpaid invoices were or what customer-specific costs had been added to serve it.
The account had its own delivery arrangement. Its stock took up space. Staff spent most of their week handling its orders. Yet every sales meeting still called this dependence “growth.”
When the customer’s procurement process delayed payment, the business did not have a sales problem. It had a cash problem.
The uncomfortable lesson is simple. Revenue is not cash. A famous customer is not a guarantee. A signed contract is not money in the bank.
The Number That Should Make You Sweat
I do not like arbitrary rules such as, “No customer must be more than this percentage of sales.” Your business may handle a large account comfortably if it pays quickly, carries good margins and your fixed costs are low.
Another business can be in trouble with the same percentage because it has loan repayments, a heavy payroll and slow collections.
So do not copy a magic number from somebody’s WhatsApp group.
Run the numbers.
For a business earning 45% of revenue from one customer, model what happens if that customer pays thirty, sixty and ninety days late. Then model the full loss of the contract. Check whether cash on hand and expected collections can cover payroll, rent, tax and loan commitments without that customer’s next payment.
That is the real test. Not whether the customer is prestigious. Not whether the procurement manager calls you “partner.”
A Second Example: The Customer Who Was Profitable on Paper
Take a Zimbabwean distributor with one supermarket group as its biggest account. The group places big orders, but demands long credit terms, special deliveries and dedicated merchandising staff. The owner sees full trucks leaving the warehouse and assumes the account is carrying the company.
Then debtor ageing tells a different story. The largest customer has the biggest overdue balance, and the margin is thinner once the dedicated costs are included. The better decision may be to keep the account, tighten collections and stop accepting work that only looks profitable from the road.
Big turnover can make you feel rich before it makes you rich.
Approach: Build a Concentration Register, Not a Hope Register
Every month, I would put the largest accounts on one page. Not in the owner’s head. Not buried in an accountant’s annual file.
A customer concentration register should show the following for each major account:
-
Its share of total revenue, because sales alone show where dependence starts.
-
Its share of gross margin, because a high-revenue customer can still be eating your money.
-
Debtor days and overdue debt by customer, because late payment can break a healthy-looking business.
-
The overdue balance as a share of available cash, because you cannot pay salaries with an invoice that is still being “processed.”
-
Contracted revenue due to expire within ninety days, because expiry dates do not care about your optimism.
-
Customer-specific fixed costs as a share of total fixed costs, because dedicated vehicles, staff or premises can remain after the account leaves. Also track what your top five customers contribute to revenue. One large customer is obvious. A group of customers under common control can be just as risky, especially where the same group makes the buying decisions.
For a private business corporation, your day-to-day cash records, credit-sales records and credit-service records must identify counterparties under Zimbabwe company law, effective from 13 February 2020. That means your records should already be capable of showing who owes you money and what you sold them.
Use them.
A basic debtor ageing report and a monthly cash flow forecast are not admin work. They are survival tools.
Put Triggers in the Boardroom Before Trouble Arrives
Set escalation triggers before the account becomes a problem. The trigger should say what management must do, who must be told and how quickly the matter reaches the board.
For example, a serious payment delay from your largest customer should trigger a revised cash forecast, a collections call and a review of stock or costs committed to that account. The exact trigger depends on your liquidity and fixed-cost cover. There is no universal safe percentage.
The step people skip is writing down the decision.
Zimbabwean directors and officers must act in good faith, in the company’s best interests, and with the care, skill and attention expected of a diligent businessperson. A concentration register, downside cash forecast and board decision trail help show that discipline.
Governance is not a suit-and-tie word for listed companies.
It is how you prove you saw the hole before the business drove into it.
Results: Diversify the Pipeline Before You Need It
When Mr Moyo’s team finally looked at the account properly, the immediate result was not dumping the customer. That would have been emotional. The result was a plan to protect cash while the sales team rebuilt a wider pipeline.
They separated new prospects from wishful conversations. They chased smaller accounts with better payment behaviour. They also stopped adding customer-specific costs unless the contract could carry them.
That is account diversification. You do not need to replace one giant customer with another giant customer. You need enough real opportunities, across different buyers, to keep one delayed payment from becoming a company-wide emergency.
Hunt daily.
Your sales pipeline should have prospects at different stages: new leads, meetings held, quotations submitted and contracts close to signature. More importantly, it should show expected cash timing, not just a beautiful total at the bottom.
A quotation is not revenue. Revenue is not cash. Cash is what pays people on Friday.
For Zimbabwe Stock Exchange issuers, customer concentration can become an investor-facing matter. IFRS 8 requires disclosure when one external customer generates 10% or more of total revenue, although the customer does not need to be named. This applies to annual periods beginning on or after 1 January 2009. Zimbabwe Stock Exchange issuers must also publish audited annual financial statements under rules effective from 25 October 2019.
A small private company may not have those public disclosure duties. But do not wait until you are listed to start thinking like a business that wants to last.
As of November 2026, I found no Zimbabwe-specific customer-concentration rule change in the previous eighteen months. The discipline remains the same: review concentration, debtor ageing and contract expiry every month, not once a year when the damage is already wearing a tie.
Quote
“One large customer can grow your business. It must never be allowed to own it.”
Frequently Asked Questions
What is customer concentration risk?
It is the risk that losing one customer, receiving payment late or getting reduced orders from that customer disrupts revenue, cash flow, fixed-cost cover or debt repayments.
Is one large customer always bad?
No. A large account can be profitable and valuable. The danger starts when you have not tested payment delays, contract loss, margin and the costs built around serving that customer.
What should I review every month?
Review your largest customer’s revenue and gross-margin share, debtor days, overdue invoices, contract expiry, customer-specific fixed costs and your top-five customer concentration. Review them alongside your cash flow forecast.
Should I fire a customer that represents a large share of revenue?
Usually, no. First understand whether the real problem is margin, payment terms, contract risk or costs that you have allowed to grow around the account. Then build alternatives in your sales pipeline while protecting the relationship.
Your business should be able to lose an account without losing its dignity, its staff salaries or its future.
If one customer’s delayed payment would make you panic this month, do not wait for the panic. Run the stress test, fix your customer concentration risk and get your sales team hunting. Then get Why African Businesses Die Young, the practical guide to building a business your people can inherit, one that can lose its biggest customer and keep standing. Enquire today for a quote on copies for you and your management team. What percentage of your revenue can walk out through one customer’s door?
