Supplier Concentration Risk When Buying a Business in Australia
Supplier concentration risk is what you've got when a business relies on one or two key suppliers for the majority of its inputs — materials, parts, product, or a critical service. In the context of buying a business in Australia, it means the seller has built their margins and their operations around a relationship that may not automatically transfer to you, and may not survive the ownership change at all. This is different from customer concentration risk, but the consequences can be just as damaging: higher costs, interrupted supply, or a wholesale repricing of the deal economics you thought you were buying.
The issue is common in trades businesses. And most buyers either don't ask about it, or ask too late.
What Supplier Concentration Actually Means
Supplier concentration means a meaningful portion of a business's purchasing — materials, parts, subcontracting, product — flows through a small number of relationships. The rule of thumb used in private equity is that any single supplier accounting for more than 30% of total purchases represents a concentration risk worth investigating. For small trades businesses, that threshold is breached routinely without the owner even being aware of it.
A plumbing business might run 70% of its materials through a single wholesaler. An electrical contractor might source all switchboards and cable from one distributor. A painting contractor might buy everything from one paint brand on a personal trade account.
None of these are automatically bad arrangements. The question is whether they survive the sale — and on what terms.
This type of risk sits squarely in operational due diligence. Module 5 of the Playbook covers how to structure the full due diligence process for small Australian business acquisitions.
Why Trades Businesses Are Particularly Exposed
Service and trades businesses in Australia are structurally prone to supplier concentration for a few reasons, and understanding them helps you know where to look.
Margin is built into trade accounts. A painting business's profitability often depends on a 15-20% trade discount from a specific brand — Dulux, Taubmans, Solver. That discount is tied to the account, not the business. And the account is often in the seller's personal name (which is more than most people check before they sign).
Relationships are personal and informal. In blue-collar industries, supplier relationships are built over years, often informally. "I get a good deal because they know me" is not a transferable asset. When ownership changes, the supplier's account manager goes home and the new owner starts from scratch with whoever picks up the phone.
Working capital depends on supplier credit. A landscaping business that buys materials on 60-day terms from one key supplier may have its entire working capital model underwritten by that relationship. Lose the credit terms, and you've suddenly got a cash flow problem you didn't price for.
Subcontractors count as suppliers too. If a fencing business subcontracts 40% of its jobs to one crew who work almost exclusively for this business, that's a form of supplier concentration — and one that can walk out the door after settlement with no warning and no contractual obligation to stay.
I saw a commercial cleaning business recently that sourced all its cleaning products from a single distributor at negotiated contract pricing. The contract was between the distributor and the seller personally. After settlement, the buyer spent six months renegotiating — and ended up paying 18% more for the same products while they built enough purchase history to qualify for equivalent terms. The seller had mentioned the "great supplier relationship" three times during the sales process (which, to be fair, it was — for the seller).
Red Flags to Look For
You won't see supplier concentration risk on the face of a profit and loss statement. You have to ask for it. Some signs that should prompt further investigation:
Gross margins that sit above industry norms. If a trades business is running margins materially better than typical for the sector, some of that may reflect supplier arrangements — pricing, rebates, or volume discounts — tied to the current owner. Worth understanding before you assume those margins are structural.
Vague answers about where materials come from. Sellers who say "we have a really good relationship with our supplier" without naming the supplier, explaining the commercial terms, or being able to produce documentation are telling you something, even if they don't mean to.
Creditor payments concentrated in one entity. When you get access to the accounts payable ledger in due diligence, look at supplier diversity. If 60-70% of creditor spend flows through one name, that's your concentration — and your investigation starting point.
Credit terms that seem better than market. Extended terms (60 or 90 days) from a supplier can reflect good relationship management. They can also reflect a relationship a new owner won't inherit.
Rebates or volume incentives that the business seems to depend on. These often appear as credits against cost of goods in the financials. Find out if they're documented, on what basis they're calculated, and whether they'd continue post-sale.
It's worth adding these to your due diligence checklist alongside the standard financial checks.
How to Assess Supplier Concentration in Due Diligence
This sits in operational due diligence — not the initial financial review, and definitely not a skim of the information memorandum. You need actual creditor data over at least 24 months to form a view.
Step 1: Request a full creditor analysis by annual spend. Ask for a list of every supplier and the total amount paid over the last two financial years, by supplier. Calculate each supplier's share of total purchases. Any single supplier above 25-30% warrants a more detailed look.
Step 2: Determine whether trade accounts are in the business name or personal name. This is the most important question for trades businesses. If the account is personal — and in Australian trades businesses, it often is — the supplier has no obligation to transfer it, offer the same terms, or honour existing pricing. Ask to see the account agreements.
Step 3: Request copies of any supplier contracts or pricing agreements. Most small trades businesses don't have formal supplier contracts, which is itself useful to know. If there are rebate agreements, preferred supplier arrangements, or volume pricing schedules, you need to see them and confirm whether they're assignable to a new owner.
Step 4: Understand the credit history and terms in detail. Get a trade reference from the key supplier that includes the current terms. Then find out what a new business would typically be offered as a starting position — the gap between the two is a rough quantification of the risk.
Step 5: Talk to the key supplier (in confirmatory due diligence). This feels uncomfortable but it's entirely legitimate once you're in confirmatory due diligence and the deal is progressing seriously. A conversation with the supplier's account manager will tell you whether they know about the sale, whether they're willing to continue the relationship, and on what terms. Most suppliers will say yes. Some won't. Better to know before settlement than after.
The operational due diligence checklist includes a supplier review section that covers all of these steps.
What to Do If You Find Supplier Concentration
Finding supplier concentration in due diligence doesn't mean you walk away. It means you price the risk.
Get a commitment in writing before settlement. Approach the key supplier and ask them to confirm in writing that they'll continue the relationship on the same terms with the new owner. Not all suppliers will do this — they may want to see how the new owner operates — but many will, especially for a long-standing account. A letter of support from the supplier has real value when you're deciding whether and how to proceed.
Use it as a price reduction lever. If the supplier won't commit, or if the account is personal and unlikely to transfer smoothly, that's a material risk that affects the value of the business you're paying for. You're entitled to reflect that in the offer — either through a lower purchase price, or through an earn-out structure that ties part of the payment to the business maintaining its cost base in the first 12-18 months after settlement.
Structure the seller handover to include supplier introductions. The seller handover period is often discussed in terms of customer relationships, but it's equally valuable for supplier introductions. Make it explicit in the sale and purchase agreement: the seller accompanies you to introduce you personally to key suppliers and facilitate account transitions within the first 30 days after settlement. It doesn't cost the seller anything, but it's worth a lot.
Start building alternative supplier relationships before day one. If the timeline allows and the seller is cooperative, there's nothing stopping you from beginning conversations with alternative suppliers while you're still in due diligence — so you're not starting from scratch on day one if the primary relationship doesn't survive.
What you shouldn't do is assume the relationship transfers automatically and deal with the consequences later. It doesn't show up as a problem immediately. It shows up three months in, when you're renegotiating terms you assumed were locked in, and your accountant is asking why your margins are soft.
The Connection to Customer Concentration
Supplier and customer concentration often travel together. A business with one dominant customer tends to have built its supply chain specifically around that customer's requirements — which typically means one key supplier providing specialised materials or product for that customer's jobs. Lose the customer, and you're suddenly over-committed to a supplier whose product no longer makes sense at the volume you were buying.
If you're already thinking about customer concentration risk when buying a business, treat supplier concentration as the back half of the same investigation. The due diligence process for a small business should address both systematically, not as afterthoughts.
Want the full operational due diligence checklist, including the supplier review section? Grab it free at /resources/operational-due-diligence-checklist-buying-business-australia.
And if this kind of thing is useful — the stuff that doesn't make it into the glossy broker information memorandums — The Leveraged Worker newsletter covers it each week. More at /blog.
FAQ
What is supplier concentration risk when buying a business?
It's the risk that a business depends on one or two key suppliers for most of its materials or inputs, and that those arrangements may not continue — or may cost significantly more — after a change of ownership.
How much supplier concentration is too much?
Any single supplier above 30% of total purchases warrants investigation. Above 50% from one supplier is a material due diligence concern that should affect your offer price or structure.
Do supplier trade accounts transfer automatically when you buy a business?
Not automatically. Accounts held in the seller's personal name don't transfer at all. Accounts in the business name usually continue, but pricing, credit terms, and discounts may change at the supplier's discretion with a new owner.
What should I ask the seller about their key suppliers?
Ask: are the accounts in the business name or personal name? What are the current credit terms? Are there formal pricing or rebate agreements? Will the supplier meet with me before settlement to confirm the relationship?
Is supplier concentration a deal-breaker?
Rarely on its own. It's a risk to quantify and price, not necessarily a reason to walk away — provided you can get commitments from the supplier or reflect the uncertainty in what you pay.