With mandatory climate-related disclosures under AASB S2 now underway for Group 1 entities and Group 2 entering the phase in 2026, Australian accountants are increasingly tasked with handling greenhouse gas emissions data. Scope 1, 2, and (phased) Scope 3 emissions form a core part of the metrics and targets pillar, requiring accurate measurement, credible disclosure, and strategic advice to clients on reduction pathways and risks.
This deep dive outlines practical steps accountants can take to measure and report these emissions effectively. By building structured processes and leveraging available tools, practices can turn a complex regulatory requirement into a value-adding service that supports client resilience and compliance.
Understanding the Emissions Scopes Under AASB S2
AASB S2 requires disclosure of gross GHG emissions in metric tonnes of CO₂ equivalent, classified into Scope 1 (direct emissions from owned or controlled sources), Scope 2 (indirect emissions from purchased energy), and Scope 3 (other indirect emissions across the value chain). Scope 1 and Scope 2 are mandatory from the first reporting period, while Scope 3 benefits from a one-year transition relief, allowing entities to focus initial efforts on the more controllable direct and energy-related emissions.
The standard aligns measurement with the GHG Protocol Corporate Standard hierarchy, prioritising activity data and location-based or market-based methods for Scope 2. For Scope 3, entities must use reasonable and supportable information, starting with screening to identify material categories before refining estimates. This phased approach recognises data challenges, particularly for value chain emissions, and encourages progressive improvement in accuracy over time.
Accountants play a key role in ensuring emissions data integrates with financial reporting, supports materiality assessments, and informs client strategies on transition risks and opportunities.
Practical Steps for Measuring Scope 1 and Scope 2 Emissions
Begin by defining organisational and operational boundaries clearly, consistent with AASB S2 and the GHG Protocol. For most clients, this involves the equity share or operational control approach, depending on their structure and existing NGER reporting obligations if applicable.
Collect activity data from reliable sources such as utility bills for electricity (Scope 2), fuel purchase records for vehicles or on-site combustion (Scope 1), and refrigerant usage logs. Apply Australian-appropriate emission factors from sources like the National Greenhouse Accounts Factors or NGER methods to convert activity into CO₂-e tonnes. Many accountants start with spreadsheets for initial calculations, then migrate to dedicated carbon accounting software for automation and audit trails as volumes grow.
For Scope 2, decide between location-based (grid average factors) and market-based (contractual instruments like green power certificates) methods. Both may be disclosed to provide a fuller picture, with market-based often reflecting client procurement choices. Regular reconciliation against financial records helps verify data completeness and accuracy, reducing the risk of restatements in future periods.
Document assumptions, methodologies, and any changes from prior periods transparently. This supports assurance processes as limited assurance phases in and builds credibility with stakeholders reviewing the sustainability report.
Approaching Scope 3 Emissions Measurement and Phased Disclosure
Scope 3 presents the greatest challenge due to its value chain breadth, covering 15 categories such as purchased goods, upstream/downstream transportation, and use of sold products. AASB S2 allows a screening process to prioritise material categories, using spend-based, average-data, or supplier-specific methods depending on data availability.
Start with a high-level materiality assessment: map the client’s value chain, estimate emissions using industry averages or spend data from financial systems, and identify hotspots (often purchased goods/services or transportation for many Australian businesses). Engage key suppliers early to request primary data where feasible, framing requests around mutual benefits like collaborative reduction targets.
As transition relief applies in the first year, focus initial reporting on qualitative descriptions of Scope 3 risks and planned improvements. Over time, refine estimates by building supplier engagement programs or adopting hybrid calculation approaches. Tools like emissions databases or platforms that integrate with accounting software can streamline this, providing default factors while allowing overrides for client-specific data.
Accountants can add significant value here by advising on how Scope 3 links to financial impacts, such as supply chain disruptions or financing conditions tied to emissions performance, helping clients prioritise actionable categories.
Tools and Processes to Make Emissions Data Manageable
Enhance workflows by integrating emissions tracking into existing practice management or ERP systems where possible. Many firms use dedicated carbon accounting platforms that import data from Xero or MYOB, apply factors automatically, and generate reports aligned with AASB S2 requirements.
Implement internal controls such as data validation checklists, version tracking for calculations, and periodic reviews to ensure consistency. Training team members on GHG Protocol basics and AASB S2 specifics builds capability without overwhelming resources.
For clients with limited internal expertise, accountants can guide on starting small: establish a baseline using available data, set interim targets, and monitor progress through dashboards that link emissions to financial metrics. This practical foundation supports credible disclosures and positions the firm as a strategic partner in sustainability.
Some practices manage increased data demands by exploring offshore support for routine emissions calculations or data collation, allowing onshore teams to concentrate on advisory interpretation and client strategy discussions. For guidance on such options, see our resources on how to prepare for accounting outsourcing or the BOSS Outsourced Accounting FAQ.
Sources
AASB S2 Climate-related Disclosures standard (2024).
CA ANZ Understanding and Navigating Scope 3 Emissions guide (2025).
CPA Australia Carbon Accounting resources (2025).
Australian Government National Greenhouse Accounts Factors (2025 update).
ASIC Regulatory Guide 280 Sustainability Reporting (2025).
Industry guidance from Accountants Daily on AASB S2 implementation (2025–2026).
Frequently Asked Questions
What is the difference between Scope 1, 2, and 3 emissions under AASB S2?
Scope 1 covers direct emissions from owned/controlled sources, Scope 2 indirect emissions from purchased energy, and Scope 3 other value chain emissions. Scopes 1 and 2 are required from year one, with Scope 3 often phased in after transition relief.
How should accountants start measuring Scope 1 and 2 emissions for clients?
Define boundaries, collect activity data from bills and records, apply Australian emission factors, and document methodologies. Use spreadsheets initially, then consider integrated software for accuracy and scalability.
What transition relief applies to Scope 3 reporting?
A one-year relief allows entities to omit Scope 3 disclosures in the first reporting period, focusing instead on qualitative information about value chain risks and future plans while building data capabilities.
Which tools help streamline emissions calculations?
Carbon accounting platforms that integrate with accounting software, apply factors automatically, and generate AASB S2-aligned reports are useful. Many start with free databases and spreadsheets before advancing to dedicated tools.
How can accountants advise clients on Scope 3 hotspots?
Conduct screening assessments using spend or industry data to identify material categories, engage suppliers for better information, and link emissions to financial risks like supply chain costs or financing terms.
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