ISO 14064-3 Verification: Getting Your GHG Inventory Verified

What is ISO 14064-3 verification of a GHG inventory?

It is the independent review of a greenhouse gas (GHG) statement that has already been prepared, carried out under ISO 14064-3:2019 and ending with an opinion on its reliability. It covers historical data: last year’s inventory, not your projections.

The full title is “ISO 14064-3:2019 — Greenhouse gases — Part 3: Specification with guidance for the verification and validation of greenhouse gas statements”. This second edition was published in April 2019 by subcommittee ISO/TC 207/SC 7; it cancelled and replaced ISO 14064-3:2006, and ISO confirmed it in 2024. The text runs to 54 pages and is sold in English, French and Spanish. According to iso.org, it applies to organization, project and product GHG statements and is GHG-programme neutral: if a programme applies to you (a regulatory scheme, a registry, a customer’s specification), its requirements come on top of the standard’s.

This guide takes the side of the company being verified. To build the inventory itself, see our ISO 14064-1 requirements guide; for the full service, from scoping to verification, see our page on GHG inventories to ISO 14064.

Verification, validation or agreed-upon procedures?

ISO 14064-3:2019 distinguishes three types of engagement. Choose before you sign, because the type decides what you receive.

The foreword states that no opinion is expressed on an agreed-upon procedures engagement: the intended users interpret the findings. Annex D covers mixed engagements that combine these types.

The clauses that matter to the verified company

The table of contents is public on iso.org; the requirements themselves are in the paid text.

The standard also defines the players. The responsible party provides the GHG statement and its supporting information; usually, that is your company. The intended user relies on the statement to make decisions: a customer, a bank, a programme administrator, a regulator. The client is whoever requests the verification. The verifier is a competent and impartial person, and the independent reviewer a competent person who is not part of the verification team.

Certification or verification: what can you actually get for a carbon inventory?

Verification, never certification in the sense of a management-system certificate. The company receives an opinion on a specific statement, for a given period and boundary, at an agreed level of assurance.

“ISO 14064 certification” is a common phrase, but it does not match what the standards provide: ISO 14064-1:2018 sets out how to quantify and report an inventory, ISO 14064-3:2019 how to verify it. Neither provides for certifying the company itself, the way ISO 14001 does for an environmental management system.

The verification regulation of the Moroccan Standards Institute (Institut marocain de normalisation, IMANOR) is explicit (section 10.4): the holder must never present the verification opinion as a certification, a recognition of environmental performance or a permanent validation beyond the boundary and period verified. In case of misleading use, IMANOR may demand that the use stop, publish a clarification, or withdraw or suspend the opinion.

Under IMANOR’s scheme, the opinion states the boundary assessed, the period covered, the level of assurance and the conclusion on the conformity and reliability of the statement; it also lists the main findings, limitations and any qualifications or nonconformities. ISO 14065:2020, for its part, has an annex on types of opinions (Annex A) and another on referring to verified statements and using marks (Annex B).

Three rules for your communications:

• quote the opinion as it stands, with its boundary, period and level of assurance;
• do not write “certified carbon footprint” or “ISO 14064 certified company”;
• do not turn a verified inventory into a neutrality claim. In the EU, Directive (EU) 2024/825 has banned, since 27 September 2026, claiming on the basis of greenhouse gas offsetting that a product has a neutral, reduced or positive impact on the environment in terms of GHG emissions. See our article on Directive 2024/825 and environmental claims and our page on carbon neutrality.

Limited or reasonable assurance: which level should you choose?

The level your statement’s user requires. Reasonable assurance gives a positive conclusion at the cost of extensive work; limited assurance gives a negative conclusion after fewer tests. The level is agreed before the engagement, with the verifier and the recipient.

ISO 14064-3:2019 added requirements and guidance on the use of levels of assurance, and an Annex A on limited assurance verifications. For plain definitions, the clearest EU text is recital 60 of Directive (EU) 2022/2464 (CSRD): a limited assurance conclusion is usually expressed in negative form, stating that nothing has been identified to conclude that the subject matter is materially misstated; a reasonable assurance conclusion is usually expressed in positive form, and the work includes consideration of internal controls and substantive testing. IMANOR’s regulation sums it up: a high level of confidence based on extensive evidence gathering in one case, a moderate level based on targeted checks in the other.

Two regulatory reference points, checked on 11 November 2026:

• CSRD. Your European customer’s auditor gives an opinion based on a limited assurance engagement. Directive (EU) 2026/470 (Omnibus) removed the requirement for the Commission to adopt reasonable assurance standards, to avoid higher assurance costs, and pushed the adoption of limited assurance standards back to 1 July 2027 (Article 26a of Directive 2006/43/EC, as amended by Article 1 of Directive 2026/470). Its recitals also ask assurance providers to respect the protections given to companies in the value chain. More on our page on CSRD, VSME and ESG questionnaires.
• CBAM. According to the European Commission, CBAM verifiers provide reasonable assurance that the calculation of embedded emissions is correct.

For a first voluntary verification, limited assurance tests your method and your evidence file; move to reasonable assurance when a recipient requires it or once your internal controls are mature.

The other parameter to agree is the materiality threshold: the size of error above which it counts as material. It is set in the contract or imposed by the applicable GHG programme.

Who can verify your inventory: ISO 14065, ISO 14066 and accreditation?

An independent body that meets ISO 14065:2020, with a team competent under ISO 14066:2023, and accredited if your recipient requires it. Whoever prepared your inventory cannot verify it.

ISO 14065:2020 — “General principles and requirements for bodies validating and verifying environmental information”. Third edition, published in December 2020, confirmed in 2026, 31 pages; it replaced ISO 14065:2013. According to iso.org, it is a sector application of ISO/IEC 17029:2019. Its scope now covers all environmental information, with an Annex E specific to GHGs, and it is the basis for accrediting verification bodies.

ISO 14066:2023 — “Environmental information — Competence requirements for teams validating and verifying environmental information”. Second edition, published in August 2023, 24 pages; it replaced ISO 14066:2011 and widened its scope from GHGs to all environmental information. It is sold in English and Spanish only. It covers the team, technical experts and the independent reviewer, and stresses professional scepticism, defined as an attitude that includes a questioning mind and a critical assessment of evidence.

How to choose a verifier

• Does the statement’s recipient (customer, bank, programme) require an accredited verifier, and against which standard?
  
• An accreditation certificate to ISO 14065:2020 is provided, naming the accreditation body and a scope that covers organization-level GHG statements.
  
• The body took no part in preparing your inventory and has not advised your company on it.
  
• The proposed team has experience in your sector; a technical expert is planned if your processes are specific.
  
• An independent reviewer, outside the team, reviews the file before the opinion.
  
• The proposal states the engagement type, level of assurance, criteria, period, boundary and materiality threshold.
  
• Rules on appeals, confidentiality and use of the opinion are in writing.
  

In Morocco: IMANOR’s verification scheme

IMANOR has published a regulation on the verification of greenhouse gas statements (reference RVDGES01, version 01, applicable from September 2025). Based on NM ISO 14064-3, the Moroccan adoption of ISO 14064-3, it sets the framework for the verification engagements IMANOR carries out:

• Legal basis: Law 12-06 on standardisation, certification and accreditation, and Law 75-24, which supplements it and designates IMANOR as the reference body for certifying carbon content (section 4.1 of the regulation).
• Reference standards: NM ISO 14064-1, NM ISO 14064-3, NM ISO 14065 and NM ISO 14066; IMANOR qualifies its verifiers against the NM ISO 14066 criteria.
• Scope: all sectors and all GHGs, in a regulatory or voluntary context, at a reasonable or limited level of assurance depending on the needs of the applicant or the intended user.
• Applicants: any private or public organization, whatever its size, with a finalised, documented inventory under a recognised GHG programme.
• Independent review by an examiner outside the team, and a national register of organizations whose statements have been verified.

The regulation does not say whether this verification activity is itself accredited to ISO 14065:2020. If your customer or lender requires an accredited verifier, ask before you apply.

The CBAM case

For the embedded emissions of an installation exporting cement, fertilisers, iron and steel, aluminium, hydrogen or electricity to the EU, the rule is different. According to the European Commission, only national accreditation bodies of EU (or EEA) countries grant CBAM accreditation; a verification company established outside the EU may apply to any accreditation body offering the service. The first CBAM verification reports are expected from January 2027, and declarants will finalise their declarations for 2026 in September 2027. See our article on the CBAM definitive period and our page on CBAM for exporters.

How does a verification run, step by step?

In five stages: scoping and contract, preliminary analysis and plan, site visit and evidence gathering, findings and corrections, then report, independent review and opinion. IMANOR’s regulation, aligned with ISO 14064-3, sets them out precisely.

1. Application. You submit a form and your GHG statement. Annex 1 of IMANOR’s regulation sets its minimum content: period and boundaries, sources by scope, GHG types, programme, emission factors and their source, uncertainty, assumptions and exclusions, results, and a signed statement of accuracy.
2. Admissibility. The verifier checks that the statement is complete and consistent, that the level of assurance suits the intended user and the programme, and that it has the competence and schedule required.
3. Proposal and contract. According to IMANOR, the duration of the engagement, and therefore the proposal, depends on the size of the organization, the number of sources and sites, data complexity and the level of assurance.
4. Inventory quality plan and team. You send your GHG inventory quality plan; IMANOR proposes a team, which you may challenge for a substantiated conflict of interest within two working days.
5. Preliminary analysis. The team reviews your emission sources, calculation methods, data collection systems and error risks; this is the basis for the verification plan.
6. Verification plan. It lists the data to verify, the sites to visit, the sampling plan and the schedule. A multi-site organization is verified on a representative sample of sites.
7. Site visit. Observation, review of records and interviews: whether emission sources exist, how measuring equipment works, how reliable monitoring and internal control procedures are.
8. Findings and corrections. During the engagement, the lead verifier flags conforming and nonconforming points and anomalies; you may supply further evidence or correct some errors before the final report.
9. Report, independent review and opinion. The report describes the work, the method (sampling, cross-checks, recalculations), limitations, areas for improvement and the conclusion. It goes through independent review, then you receive the opinion.
10. After the opinion. With IMANOR, a written, reasoned appeal is possible within seven working days. Clause 10 of ISO 14064-3:2019 deals with facts discovered after the verification.

Under IMANOR’s scheme, steps 5 to 9 take no more than three months, from the preliminary analysis to delivery of the verification report. The opinion goes only to the verified organization, or as the GHG programme provides, and can be shared with third parties only with its written consent or under a legal obligation.

How do you prepare your company for verification?

By building, from the first inventory, a quality plan and an evidence file that let anyone trace every reported tonne back to its supporting document.

Annex 2 of IMANOR’s regulation is a good list of what a verifier expects in the GHG inventory quality plan:

• a description of the organization, the list of emission sources and flows to monitor, and a simple diagram of sources, sampling points and measuring equipment;
• the allocation of monitoring and reporting responsibilities, and how staff competence is managed;
• the data flow, from primary data to emissions, with the formulas and IT systems used;
• calculation methods, uncertainty levels, default values and their sources;
• measurement methods and equipment, with frequency, range and uncertainty;
• testing laboratories, accredited to NM ISO 17025 or able to prove their competence;
• the plan’s version number and effective date;
• where relevant, NM ISO 14001 or NM ISO 50001 certificates.

Checklist before you have your inventory verified

• The intended user and its requirements are written down: level of assurance, accreditation, GHG programme, format of the opinion.
  
• The GHG statement is final, signed and dated, with its boundary and period.
  
• The inventory quality plan is up to date and version-controlled.
  
• Every activity data point traces to a document: invoice, meter reading, delivery note, refrigerant log.
  
• Every emission factor has its source, year and region in a register.
  
• Significant exclusions and assumptions are justified in writing.
  
• Meters and measuring equipment have calibration certificates.
  
• Estimates (missing month, broken meter) follow a written rule.
  
• A mock review has been done by someone who did not do the calculation.
  
• Figures already sent to customers match the statement.
  

The most frequent findings

Findings rarely concern a wrong calculation. They concern an unwritten boundary, a forgotten source (back-up generator, refrigerant, leased vehicle), a factor with no source or year, an estimate that changes from month to month, or a figure sent to a customer that differs from the report.

Which verification will your customers, banks and importers require?

Each one sets its own level of evidence. Ask before choosing a verifier, because the same statement may need two different verifications.

For lenders’ requirements, see our page on EBRD and IFC ESG requirements; for the wider ESG picture, our ESG and CSR page.