ACCU Buyer Due Diligence: What to Check Before You...

A procurement manager at an ASX-listed industrial company recently sent a one-line email to their broker: "Need 50,000 ACCUs by end of quarter, cheapest available." That email, if it ever surfaces in an ACCC investigation or AASB S2 audit working paper, is a problem. Not because buying ACCUs is wrong. Because "cheapest available" is not a defensible procurement standard for an instrument the Federal Court has now described as a financial product carrying integrity risk.

We build carbon accounting software, not a brokerage. We do not buy, sell or hold ACCUs on behalf of customers. But we sit close to the people who do. And what we keep seeing is the same gap: serious finance teams who would never sign a $2 million capex without a full options analysis are signing offset purchase agreements after one phone call and a PDF from a project developer.

The Chubb Review changed what reasonable due diligence looks like. So did the Safeguard Mechanism reforms. So did the ACCC's run of greenwashing cases. If your company is planning to buy Australian Carbon Credit Units or Safeguard Mechanism Credits in the next 12 months, this is what we think a defensible pre-purchase process looks like.

Why the Bar Just Moved

The Independent Review of ACCUs, chaired by Professor Ian Chubb and delivered to government in December 2022 (published January 2023), made 16 recommendations. The headline finding was that the scheme was "fundamentally well-designed". That sentence got quoted a lot by the Clean Energy Regulator. Less quoted: the recommendations themselves, which included closing the avoided deforestation method, restructuring governance of the ERAC, separating method development from regulation, and substantially tightening the Human-Induced Regeneration (HIR) method.

HIR was the method generating most ACCU volume for years. It rewards landholders for letting native vegetation regrow on cleared land. The academic critique, led by Professor Andrew Macintosh at the ANU Crawford School, argued that satellite imagery showed regrowth happening in places that had not actually been cleared, or where the credited regrowth was not attributable to project activity. Macquarie University researchers reached similar conclusions in peer-reviewed work. The CER pushed back, the Clean Energy Regulator's published response maintains the methods were sound, and the public debate is still live.

You do not have to take a side in that debate to act on it. The point is that integrity of supply varies, and the market knows it. That is why the secondary market consistently shows a price gap between Generic ACCUs and credits from specific high-integrity methods. It is also why the Integrity Council for the Voluntary Carbon Market (ICVCM) Core Carbon Principles exist as a separate quality overlay. A credit that meets CCP standards is a different commercial product than one that just clears the CER's minimum bar.

If you are a director or CFO signing an offset purchase, "the regulator approved it" is no longer the end of your due diligence. It is the start.

Methodology Mix Is the First Question

ACCUs are not fungible in any meaningful sense beyond the registry. A tonne credited under a landfill gas combustion project is generated by physically destroying methane that would otherwise have vented. You can meter it. You can audit the flare. The additionality question is largely a question of whether the project would have happened anyway without the credit revenue.

A tonne credited under a soil carbon project is fundamentally different. The carbon is in the top layer of farmland soil. Measurement uses sampling protocols with real uncertainty bands. Permanence depends on the landholder not ploughing, not changing land use, not losing the project to a bushfire over a 25 or 100 year period. None of that makes soil carbon worthless. It makes it a different risk profile, and it should price differently.

A practical methodology hierarchy for a risk-averse buyer in 2026 looks roughly like this. Landfill gas, alternative waste treatment, and industrial energy efficiency credits sit at the top because measurement is direct and additionality is reasonably defensible. Savanna fire management, which uses early-dry-season burning to reduce late-season wildfire emissions, has reasonable measurement science and significant Indigenous co-benefits, though the methodology has had its own integrity debates. Environmental plantings sit in the middle: real, measurable, but permanence-dependent. Soil carbon and HIR sit at the higher-risk end, not because they are necessarily bad projects, but because the integrity controversy is unresolved and your reputational exposure is higher.

We are not telling you which to buy. We are saying your purchase order should specify methods, not just volumes and vintages. "50,000 ACCUs, mixed methodology, lowest cost" is a procurement instruction written by someone who does not understand the product.

How to Actually Read a Project Page on the ACCU Registry

The CER publishes every registered project on the ANREU and ERF project register. Most buyers we talk to have never opened it. They should.

A project page tells you the proponent, the method, the location, the crediting period, the start date, the audit history, and the total ACCUs issued to date. That last figure is the one to read carefully. A project that has issued well above the modelled baseline for its method, especially in early years, deserves a question. A project whose ACCU issuance pattern jumps dramatically between audit cycles deserves another. Audit reports themselves are not always public, but the audit firm and audit dates are, and they are a useful signal.

Look at the crediting period choice. Vegetation projects can elect 25-year or 100-year permanence. A 100-year project carries a 5 percent buffer contribution and a more durable obligation; a 25-year project carries 20 percent and is, in plain English, a shorter promise. For a buyer planning to use credits against an AASB S2 net-zero claim that goes out to 2050, a 25-year-permanence credit retired in 2026 is a structurally short answer to a structurally long question. That does not disqualify it. It does mean your transition plan disclosure should be honest about the mismatch.

For property and infrastructure buyers, our earlier write-up on reading the integrity signals in the ACCU market in 2026 walks through some of the same registry mechanics in more detail.

The AAU vs ACCU Price Spread Tells You What the Market Thinks

In a healthy market for a homogeneous commodity, you would expect tight spreads. The Australian carbon market does not show tight spreads. Generic ACCUs and method-specific ACCUs (HIR-only, savanna, landfill gas) regularly trade with material differences. Safeguard Mechanism Credits, which are a completely separate instrument issued to Safeguard facilities that beat their baseline, trade at yet another level.

That dispersion is information. The market is telling you that buyers with sophisticated integrity policies are paying more for credits they can defend, and credits with weaker defensibility are clearing at a discount. If your broker quote is well below the published market average and you have not asked why, you are buying integrity risk without pricing it.

Safeguard Mechanism Credits (SMCs) deserve their own consideration. SMCs are issued under the Safeguard Mechanism reforms when a covered facility beats its declining baseline. The integrity profile is different from ACCUs because the underlying activity is industrial abatement at a facility already subject to mandatory reporting and audit under NGER. That gives SMCs a different defensibility story for a Safeguard-liable buyer. It does not make them automatically superior for voluntary use, and the supply pool is much shallower.

The ICVCM and Climate Active Overlays

The ICVCM Core Carbon Principles are a global quality threshold. CCP-eligible methodologies are published progressively, and a credit from a CCP-approved methodology carries a brand of integrity that goes beyond domestic regulator approval. For Australian ACCUs, the CCP assessment process has been mixed: some methods have been assessed favourably, others have not yet been ruled on, and HIR has faced sustained scrutiny.

Climate Active is the other overlay most Australian buyers encounter. The scheme requires retiring eligible offsets against a measured boundary to achieve certification. As covered in our piece on what net-zero claims actually mean in Australia, the federal government's Climate Active review has signalled significant changes, and the term "carbon neutral" is under live policy review. Retiring credits under a scheme whose underlying claim language is being rewritten is itself a transition risk.

A buyer applying genuine due diligence should be able to answer, for any planned purchase: which method, which CCP status, which Climate Active eligibility, which crediting period, and which audit history. If your broker cannot answer those, find a different broker.

ACCC Greenwashing Exposure

This is where it stops being an abstract integrity discussion. Section 18 of the Australian Consumer Law prohibits misleading or deceptive conduct in trade or commerce. The ACCC has prosecuted carbon-related claims, has issued updated environmental and sustainability claims guidance, and has signalled that vague carbon neutral marketing is a priority.

Our deeper look at ACCC greenwashing enforcement and the penalty trajectory covers the case patterns. The short version: a company that buys ACCUs from a contested method, retires them against a "carbon neutral" claim, and later faces academic critique of that method has a documentary trail that does not look favourable in litigation. The defence "the credits were approved by the CER" exists, but it is weaker than buyers seem to assume, because the ACCC is testing the consumer-facing claim, not the regulatory approval status.

For finance teams, this matters because greenwashing exposure now flows into AASB S2 risk disclosures. If "loss of social licence from a contested offset portfolio" is a material risk for your company, it has to be in the disclosure. Our AASB S2 climate risk register guide covers how to actually put that on paper.

A Pre-Purchase Checklist a CFO and Sustainability Lead Can Run Together

Before any ACCU or SMC purchase, we think the following questions should be answered in writing, jointly approved by finance and sustainability, and filed alongside the purchase order.

Check	What you are looking for
Method	Named method, not "generic". Justification for why this method fits the company's integrity policy.
Vintage and crediting period	Issuance year, 25 vs 100 year permanence, alignment with the company's target horizon.
Project register entry	Direct URL to the ANREU project page. Reviewed by procurement, not the broker.
Audit history	Auditor identity, last audit date, any compliance flags published by CER.
ICVCM CCP status	Method CCP eligibility, current assessment status.
Climate Active eligibility	If certification is the use case, eligibility confirmed against current scheme rules.
Price benchmark	Purchase price compared to published market range for that method. Variance explained.
Counterparty	Broker or developer creditworthiness. Custody and retirement process documented.
Use case	Voluntary, Safeguard surrender, or Climate Active. Documented and consistent with public claims.
Greenwashing review	Marketing language tested against ACCC guidance. Sign-off by legal or external advisor.

That is ten questions. None of them are exotic. Most procurement teams already apply equivalents to far less risky purchases. The fact that offsets often skip this process is not a sign that offsets are special. It is a sign that the function buying them has not yet matured.

Where Carbonly Fits, Honestly

We do not broker credits. We do not maintain a buyer's marketplace, and we have no commercial interest in steering you toward any particular project. What we do is the boring work that sits underneath defensible offset use: the measured emissions inventory the credits are supposed to address.

Our scenario builder lets a transition planner model a residual-emissions trajectory under different reduction pathways, so the volume of credits you would need is a derived output, not a guess. The targets module tracks progress against an SBTi-aligned pathway so retirement decisions sit in a strategy, not a panic buy. The MACC and action library help you defend why you are buying credits rather than abating further internally, which is increasingly the question auditors are asking. The audit trail and source-document tracking module is where credit retirement statements and registry confirmations get filed against the period they relate to, so a future assurance provider can reconstruct the claim.

We are not the answer to "should I buy ACCUs". We are the answer to "can I prove what I emitted, what I reduced, what I retired, and why". If you cannot answer those four questions cleanly, no offset purchase will hold up under AASB S2 assurance or ACCC scrutiny.

One Action to Take This Week

Pull the last 24 months of any offset retirements your company has made. For each, write down the method, the project ID, the price paid, the use case, and the public claim it supported. If any of those fields is blank, that is the first work to do, before the next purchase order. Defensible offsetting starts with knowing what you already bought.

ACCU Buyer Due Diligence: What to Check Before You Purchase a Single Tonne