Your Biggest Customer Just Became a Climate Reporter. The Scope 3 Questionnaire Is Coming.

On 1 July 2026, Australia’s second cohort of mandatory climate reporters came into scope. Entities in that group must prepare sustainability reports for financial years commencing on or after that date.

If you run a small or mid-sized business, your instinct is that this has nothing to do with you. You are almost certainly right that you do not have to report. And you are almost certainly wrong that it has nothing to do with you.

Because AASB S2 requires those entities to disclose Scope 1, Scope 2 and Scope 3 greenhouse gas emissions. Scope 3 is their value chain. Their value chain is you.

You are not required to report. You are about to be required to answer.

Every article written about mandatory climate reporting is written for the reporting entity: the listed company, the large private group, the super fund. Almost nobody is writing it for the supplier sitting three links down the chain, who will never file a sustainability report in their life and who is nonetheless about to receive a spreadsheet with their name on it.

That spreadsheet is the whole story. Your customer’s directors have to sign off on a disclosure that includes emissions you generated on their behalf. They cannot produce that number without you. And they cannot produce it from a guess.

“Reasonable and supportable information”: the phrase that changes the conversation

AASB S2 sets an information threshold: what an entity discloses must rest on reasonable and supportable information. For Scope 3, the standard’s measurement framework pushes reporters to prioritise direct measurement and verified data from their value chain, not convenient assumptions.

Sit with what that means from where you are standing. A number you invent in a questionnaire becomes a misstatement in your customer’s annual report. Their auditors will test it. Their directors carry it. Nobody carries that risk on behalf of a supplier for very long.

So the questionnaire is not a form. Strip away the branding and the deadline and what has actually landed on your desk is a data-quality audit of your business, commissioned by your largest customer. I have spent twenty years watching organisations discover, under exactly this kind of pressure, that they cannot substantiate a number they have been reporting confidently for years. It is not a pleasant discovery, and it is a much worse one to make in front of a customer.

What a credible answer requires

Not a consultant’s report. Not a carbon-neutral logo. Four unglamorous things:

• Data you can trace to a source. Fuel purchased, electricity metered, kilometres driven, waste weighed, tied to an invoice or a meter, not an estimate someone did once in a meeting.
• A method you can describe. If you allocated emissions across customers, how? Somebody will ask, and “we split it evenly” needs to be a decision you can defend, not one you improvised the night before.
• Someone accountable for the number. Not “finance thought ops had it.”
• A check that the number is right before it leaves the building. Because once it is in your customer’s report, correcting it is not a quiet conversation.

Look at that list again. Traceable data, a defined method, clear ownership, an internal check. You have just described the operating core of an environmental management system, and you have described it without once mentioning a standard.

Which is why this ends up at ISO 14001, whether you like it or not

I am not going to pretend ISO 14001 was designed for climate disclosure. It was not. But the machinery it forces you to build is precisely the machinery this problem demands: a register of what you actually consume and emit, a compliance obligations register, monitoring and measurement with defined methods, and an internal audit that tests whether the numbers hold up.

The difference between a business with an EMS and one without, when the questionnaire lands, is not sophistication. It is calm. One of them opens a system and reads off a figure. The other one starts a group chat.

And here is the part I would push hardest, because it is the part with money in it. This is going to become a tender differentiator before it becomes a requirement. A procurement team that has just been handed a Scope 3 obligation will very quickly start preferring suppliers who make that obligation easy. Being the supplier who answers cleanly, on time, with data that survives a question, is going to win work. That window is open now and it will not stay open, because eventually everybody will be able to do it and it will just be table stakes.

Am I in scope? (Almost certainly not, but check properly)

I am deliberately not going to publish the dollar thresholds here, and I want to be straight with you about why. The obligation to prepare a sustainability report turns on section 292A of the Corporations Act and on whether you must already prepare an annual financial report under Chapter 2M. ASIC sets out three separate gateways: a corporate size test (you meet two of three thresholds, being consolidated revenue, consolidated gross assets and employee numbers), an emissions test (you are a registered corporation with NGER reporting obligations), and a value-of-assets test for registered schemes, RSEs and retail CCIVs.

Those tests have exact numbers attached, and getting them slightly wrong in a blog post is precisely the sort of thing that ends up quoted back at someone in a board paper. So: if there is any chance you are near the line, read ASIC Regulatory Guide 280 and take advice from your accountant. That is a legal and accounting question, not an ISO one, and I am not going to pretend otherwise.

What I will tell you plainly is this: your reporting obligation is not the interesting question. You can be entirely, comfortably out of scope and still lose a contract because you could not answer a Scope 3 request. The regulation applies to your customer. The consequences apply to you.

What I would do before the questionnaire arrives

1. Work out which of your customers are in scope. Large listed and large private groups, and anyone already reporting under NGER. If one of them is more than a small share of your revenue, this is now a commercial risk, not an environmental one.
2. Try to answer the question yourself, today. How much electricity did you consume last financial year? How much fuel? Can you produce the evidence in under an hour? The exercise is the diagnosis.
3. Fix the data before you fix the paperwork. A policy on a wall does not produce a defensible number. A meter reading does.
4. Decide who owns it. One name.
5. Then, and only then, think about a system, whether that is a full ISO 14001 certification or simply an EMS built to the standard’s logic without the certificate. Both work. One costs more and opens more doors.

The honest summary

A large customer of yours has just acquired a legal obligation that they cannot discharge without your data. They will be polite about it for one cycle. After that, the suppliers who cannot answer will quietly stop being on the list. Not out of malice, but because every unverifiable number in a supply chain is a risk sitting on somebody’s balance sheet, and it is not going to be theirs.

You have this financial year to be the easy supplier. I would use it.

Talk to us

If you want to know whether your environmental data would survive a customer’s scrutiny, a gap analysis is the fastest honest answer. If you want to build the system, ISO mentoring lets your own team do it with an experienced auditor over their shoulder. Costs and timelines for the full path are set out on our ISO 14001 certification cost page.

And if the questionnaire has moved past emissions and started asking about climate resilience or physical exposure, that is a different document again. A climate risk assessment is what answers it.

Email hello@streamline.business, use our contact form, or call Brisbane 07 3667 8280, Sydney 02 8315 7780, or Melbourne 03 9034 3990.

Sources: AASB S2 Climate-related Disclosures; ASIC, “Who must prepare a sustainability report?” and ASIC Regulatory Guide 280. Nothing in this article is legal, accounting or financial advice. Whether you are a reporting entity is a question for your accountant and RG 280, not for us.