Customer concentration: when one client is too much of the business

Why does concentration matter to anyone but you?

For the business, a major customer is often a source of pride — proof of capability, a steady base load, a reference for new work. For a lender, the same customer is a single point of failure. If that customer reduces orders, changes suppliers, runs a tender, restructures or simply pays late, the business’s cash flow changes overnight, and so does its capacity to service debt.

That’s why concentration shows up in almost every credit assessment of an established SME, in every ledger funder’s eligibility rules, and in most buyers’ due diligence.

How should you measure it?

Measure concentration three ways, because they can tell very different stories.

Measure	How	What it reveals
Revenue share	Top customer’s sales ÷ total sales	Dependency of the top line
Gross profit share	Top customer’s gross profit ÷ total gross profit	Dependency of earnings — often higher or lower than revenue share
Debtor share	Top customer’s balance ÷ total debtors	Exposure to one payer at any moment

Calculate each for the top one, top three and top five customers, monthly. Look at the trend.

Illustrative only; no real business. An engineering firm finds its largest customer is about 28% of revenue but 41% of gross profit and 47% of debtors at year-end. The revenue figure understates the real exposure: that customer is both the most profitable account and the slowest payer.

How do lenders respond to concentration?

Cash-flow lenders focus on what happens to serviceability if the customer is lost or delays payment. They may reduce the facility size, require stronger cover, ask for more frequent reporting, or look for property security.

Ledger funders apply concentration limits: balances from any one debtor above a set share of the ledger may be excluded from funding. Combined with exclusions for aged or disputed invoices, the fundable ledger can be much smaller than it looks. Our comparison of debtor finance and working capital loans explains the trade-off.

Property-backed lenders still care, but security and exit carry more of the decision. For concentrated businesses, a facility secured on property — from $20,000 to $5,000,000 — can provide funding that a ledger or cash-flow lender would cap.

What softens the concern?

Not all concentration is equal. A lender will look at:

• Contract. A written agreement with a meaningful remaining term, pricing mechanisms and limited termination rights.
• Tenure. A relationship spanning many years and several procurement cycles.
• Customer strength. A financially strong counterparty — though strong customers can still be slow payers.
• Switching costs. Integration, accreditation or specialised capability that makes changing suppliers hard.
• Payment history. Consistent timing, even if slow.
• Your own plan. A pipeline of other customers and a target concentration level.

Slow payment is a real consideration with large counterparties. The Payment Times Reporting Regulator reported in February 2026 that the average number of days large businesses take to pay 95% of their small business invoices rose to 64 days from 58. The regulator’s Payment Times Reports Register lets you search reported payment times for large businesses — useful evidence when modelling a major customer’s likely behaviour.

If you’d like to understand how your concentration is likely to be viewed before you apply, talk to a specialist — enquiring doesn’t involve a credit check.

How to present concentration in a funding proposal

Don’t bury it. Put it in the business overview and deal with it directly:

1. State the top-customer shares on revenue, gross profit and debtors.
2. Describe the contract, tenure and payment history.
3. Explain why the relationship is durable.
4. Show a downside scenario: what happens to cover if that customer’s volume fell by a stated amount.
5. Describe the diversification plan and progress.

Our guide to writing a funding proposal shows where this fits.

Working capital: the hidden cost of big customers

Large customers often negotiate longer payment terms, more stock held on their behalf, or both. Each adds to the working capital the business must fund. Before accepting new terms:

• Model the effect on debtor and inventory days with the working capital cycle calculator
• Price the working capital cost into the contract
• Arrange funding before the terms take effect

A business that says yes to a major account without doing this is a textbook case of overtrading. If the account requires significant upfront investment, see contract mobilisation funding.

Reducing concentration over time

• Set a target. A maximum share for any one customer that the business works towards.
• Grow around the anchor. Use the capability built for the major customer to win similar clients.
• Diversify channels. Different industries or regions reduce correlated risk.
• Price for risk. Make sure the major account earns a margin that reflects its demands.
• Tighten terms where possible. Even a modest reduction in the big customer’s payment days reduces debtor concentration.

Concentration and business value

If you might sell in the next few years, concentration matters even more. Buyers weigh the risk of losing the key customer after the owner leaves, and often respond with lower prices or deal structures such as earn-outs linked to retention. business.gov.au’s guidance on selling a business emphasises accurate valuation and preparation; reducing concentration is one of the most effective preparation steps. See our guide to making a business sale-ready.

A worked stress test

Illustrative only; no real business. A $9 million turnover packaging supplier earns about $1.3 million EBITDA, and its largest customer contributes around a third of gross profit. Annual debt repayments are $520,000, so cash cover is comfortable at roughly 2.5 times.

The finance manager runs two scenarios a lender would run:

Scenario	EBITDA effect	Approximate cover
Largest customer cuts volume by half	EBITDA falls to about $1.0m after cost savings	About 1.9x
Largest customer lost entirely, partly replaced within a year	EBITDA falls to about $0.75m in the first year	About 1.4x
Largest customer extends payment terms by 30 days	EBITDA unchanged; working capital need rises	Cover unchanged, but facility headroom falls

The third row is the one owners often miss. A customer that stays but pays later doesn’t change the income statement, yet it can absorb a large part of the working capital limit. At this business’s scale, 30 extra days on a customer buying about $3 million a year ties up roughly $250,000 more in debtors.

Presenting this table in a funding proposal does two things. It shows the lender you’ve already done the analysis they would do, and it lets you argue the structure — a slightly longer term, a larger revolving limit, or property security — on your terms rather than theirs. Try the numbers yourself with the debt service cover calculator.

Concentration on the supply side

Concentration isn’t only about customers. A business that depends on one supplier for a critical input, one distributor for market access, or one platform for most of its sales carries a similar risk. Lenders ask about it less often, but buyers ask about it every time. Document alternative sources where you can, and keep the supply agreement’s term and pricing mechanism visible in your records.

Quick concentration checklist

• Top one, three and five customers by revenue, gross profit and debtors — updated monthly
• Written contracts for the largest accounts, with remaining term noted
• Payment history for each major customer over the last year
• A downside scenario showing cover without the largest customer
• A diversification target and progress against it

Is concentration holding back your funding?

A concentrated customer base doesn’t have to limit what the business can borrow. The right structure — often property-backed — can fund a business that a ledger or cash-flow lender would cap. Tell us about the major customers, the debtors and the security available.

There’s no credit check when you first enquire, and your customer details are handled by one specialist, not circulated among lenders. Please be accurate about turnover, top-customer shares and existing debt on the form — it lets us tell you straight away which structures fit. See if you qualify.