Double Counting in GHG Reporting
Avoiding double counting is essential to ensure greenhouse gas reports and carbon claims remain accurate, credible, and trusted.
The Standards
ISO 14064-1:2018 and the Greenhouse Gas Protocol require double counting to be avoided, but whether or not double counting matters depends on how the reported information is used. This explains why national (country) inventories are compiled from a top-down approach and not from bottom-up regional or company data to avoid double counting.
The GHG Protocol defines double-counting as:
“Two or more reporting companies take ownership of the same emissions or reductions.”
Double counting can occur in three main forms:
Double counting of emissions – two entities claim the same emissions in their footprint.
Double counting of reductions – two entities claim the same avoided or reduced emissions.
Double issuance – two separate carbon credits or certificates are issued for the same reduction activity.
These distinctions are important because each has different implications for the credibility and integrity of reported data or claims. For example, double issuance can undermine the environmental integrity of a carbon market, while double counting of emissions may have less impact if the data is not used for offsetting but could still distort benchmarking or performance tracking.
Why Double Counting Matters More in Some Contexts
For corporate GHG inventories used purely for internal management, double counting may have a limited impact—though it can still mislead internal decision-makers or affect the allocation of reduction targets. However, in contexts involving offsetting, compliance obligations, or external comparisons, the consequences are far more serious. In voluntary and compliance carbon markets, double counting or double claiming of the same reduction can result in overstated environmental impact, loss of stakeholder trust, and potential non-compliance with market rules.
Double Counting Examples
Double counting in voluntary carbon accounting usually occurs in three main forms:
Two or more organisations hold interests in the same joint venture but use different consolidation approaches (e.g. equity share vs operational control), emissions from the joint venture could be double counted. Double counting is common in voluntary reporting where individual companies measure emissions in a silo without initial consultation with majority shareholders or sister companies.
The incorrect assignment of ISO Categories and GHG Protocol Scopes can result in two or more companies double counting the same emissions in the same scope.
Ownership of project reductions used for carbon credits is not clear, unique serial numbers are not issued, and there is no evidence of retirement on a suitable registry to prevent multiple claims.
Double Counting Within a Single Organisation
In our assurance work, we find instances where emissions are double counted within the same company. While this doesn’t meet the GHG Protocol definition of double counting, it is worth noting and should be avoided. A simple example is when a company reports air travel emissions using activity data (i.e., passenger kilometres x emission factor). The company also reports purchased goods and services using the spend-based method and includes the dollar value paid to air travel suppliers in the inventory. Therefore, air travel emissions are reported twice.
Assurance and Materiality Considerations
Your assurance provider will check and raise double counting issues with you and assess the materiality of the impact of double-counting on the intended users of the verified footprint or disclosure. Where double counting is identified, our auditors will consider:
The scale of the duplication relative to the total inventory.
The context, i.e. whether the footprint is used for internal reporting, external disclosure, regulatory compliance, or offsetting claims.
The potential impact on stakeholders, such as misleading investors, customers, or regulators.
In high-integrity reporting, eliminating double counting is essential for ensuring transparency, comparability, and credibility, particularly in the context of increasing scrutiny of corporate climate claims.
Feel free to contact us at info@mchugh-shaw.co.nz to discuss your assurance requirements or request our free GHG Protocol Scope vs ISO Category Comparison Table. We have over 15 years of experience and complete ISO 14064-1, GHG Protocol, ISO 14067, Airport Carbon Accreditation, Eco Choice Aotearoa, Product Stewardship and Aotearoa New Zealand Climate Standard assurance.
Last Updated August 2025