ISO 14064, UK ETS and the ISAE 3410 withdrawal
Verifying an emissions report is a different regime from assuring a sustainability disclosure, with its own standards and its own mandatory/voluntary line. UK ETS requires an accredited verifier; SECR requires none. ISO 14064 and ISO 14065 govern how the checking is done and who is allowed to do it — and the assurance standard most people still name for it, ISAE 3410, is already being withdrawn.
Mandatory for UK ETS, voluntary for SECR
The same activity — checking someone else's emissions numbers — is a legal duty under one UK regime and entirely optional under another, and the two are routinely conflated.
Under the UK Emissions Trading Scheme, GOV.UK's own guidance states the duty without qualification: 1 “Your chosen verifier must be accredited by the United Kingdom Accreditation Service (UKAS) to ISO 14065 and the Verification Regulation. The scope of their accreditation must cover the regulated activity you are reporting.”
Under SECR, the position is the opposite. DESNZ and Defra's Environmental Reporting Guidelines 2 state: “There is no requirement in the legislation for emission and energy use data, or narrative on energy efficiency action to be independently assured” — though voluntary assurance “is encouraged” as best practice. A stronger sentence in the same guidance goes further still: “There is no statutory requirement to have your environmental information audited. The statutory auditor of the financial statements is not required to audit environmental information in the Strategic or Directors’ Reports.”
No credential of any kind is legally required to prepare a SECR disclosure. That guidance is, however, dead-law bait on one point: its 2019 text recommends ISAE 3410 and “AA1000AS” as the standards to use for voluntary verification, and has not been revised since. ISAE 3410 is being withdrawn (see section 04) — cite the March 2019 guidance for the negative (no statutory requirement), never as live advice on which standard to apply.
ISO 14064-1, 14064-3 and 14065
Three ISO standards, three different jobs: quantifying, verifying, and accrediting the verifiers.
The ISO 14064 family separates the job of producing a GHG statement from the job of checking it, and adds a third standard to accredit the bodies doing the checking.
ISO 14064-1:2018 — quantification and reporting
Specifies principles and requirements for organisation-level GHG quantification and reporting.
Edition 2, published December 2018, and explicitly GHG-programme-neutral: "If a GHG programme is applicable, requirements of that GHG programme are additional" to the standard itself.
It now sits at ISO stage 90.92, "International Standard to be revised", with a successor already in development as ISO/WD 14064-1.2.
ISO 14064-3:2019 — verification and validation
Specifies requirements for verifying and validating GHG statements — the standard a verifier applies when checking someone else’s emissions report.
Edition 2, published April 2019, confirmed and at stage 90.93.
The 2019 edition reversed the title’s word order from the earlier "validation and verification" — a citation built by matching the old title order, or one referencing ISO 14065:2013’s scope, is describing a superseded document.
ISO 14065:2020 — accrediting the verification bodies
Sets requirements for the bodies that validate and verify environmental information — not for the companies being verified, but for the verifiers themselves.
Edition 3, published December 2020, reviewed and reconfirmed again in 2026.
It is a sector application of ISO/IEC 17029:2019, and its scope was deliberately broadened from GHG statements alone to "environmental information statements" generally.
This is the standard a UK ETS verifier’s UKAS accreditation is measured against.
ISO 14064-1:2018 is already scheduled for revision
ISO's own catalogue records ISO 14064-1:2018 at stage 90.92, 'International Standard to be revised', naming a successor already in development (ISO/WD 14064-1.2).
It remains the current edition today, but a page that only says 'confirmed 2024' and stops there is one revision behind.
Accreditation to ISO 14065 is what UKAS checks
Being competent at ISO 14064-3 is not the same as holding the accreditation UK ETS requires — that accreditation runs against ISO 14065 specifically.
ISO 14065 is one of sixteen accreditation activities set out in Appendix 1 of the DBT–UKAS Memorandum of Understanding 12, described there verbatim as “the accreditation of greenhouse gas validation and verification bodies.” It sits under UKAS’s wider statutory remit as the UK’s sole national accreditation body — the full legal basis, and the sixteen activities in full, are covered in our companion guide to UKAS accreditation.
One precision worth carrying: ISO 14065 is nota GB Designated Standard — it sits under “Other Requirement” in the MoU’s own classification, and is EU-harmonised in Northern Ireland. That distinction rarely affects a UK ETS verifier’s day-to-day work, but it matters for anyone tracing the accreditation’s exact legal footing.
ISAE 3410 is being withdrawn
The standard most explainers still name for GHG-statement assurance is on its way out — and the UK position on its replacement is genuinely unresolved.
The IAASB approved the withdrawal of ISAE 3410, Assurance Engagements on Greenhouse Gas Statements, in an announcement dated 8 May 2025 6. Verbatim: “The International Auditing and Assurance Standards Board (IAASB) has approved the withdrawal of International Standard on Assurance Engagements (ISAE) 3410, Assurance Engagements on Greenhouse Gas Statements”, with the withdrawal taking effect “from the effective date of ISSA 5000” — that is, 15 December 2026, a date this entry derives rather than one the announcement states directly. Internationally, ISAE 3000 (Revised) also ceases to apply to sustainability engagements from that same date.
For the UK specifically, this is unresolved. The FRC’s own Assurance Standards page 8 still lists ISAE (UK) 3000 (July 2020) as a current standard, and lists no ISAE (UK) 3410 at all. ISSA (UK) 5000 ¶11 7does say the practitioner performing an ISSA (UK) 5000 engagement “is not required to apply ISAE (UK) 3000” — but that narrower statement is not the same as a UK withdrawal of ISAE (UK) 3000 itself, which has not been located from a primary source. Do not assert that ISAE (UK) 3000 is withdrawn for UK sustainability engagements.
No UK entity is under a legal duty to assure sustainability disclosures
UK ETS's mandatory verification is the exception, not evidence of a general rule — stated regime by regime.
Under the Companies Act 2006, 9 section 414CB imposes disclosure duties only; no assurance, audit or verification obligation appears anywhere in the section. Under UK SRS, the FRC’s own FAQ 10 states plainly: “No. Reporting against the UK SRS is not currently mandatory.” Under FCA CP26/5, 11the FCA states it is “not proposing to set mandatory requirements for the assurance of sustainability reporting at this time” (¶7.5).
Set against that, UK ETS’s duty is real, mandatory, and narrow: it verifies a regulated emissions report under a specific trading scheme. Treating it as evidence that sustainability assurance is mandatory anywhere else in UK law is the error this page exists to correct.
UK entities under a legal duty to assure sustainability disclosures
Across the Companies Act 2006, UK SRS, and FCA CP26/5, none imposes an assurance, audit or verification duty over sustainability disclosures.
UK ETS's accredited-verification duty sits outside that count — it verifies a regulated emissions report, not a sustainability disclosure.
Does UK ETS require accredited verification of emissions data?
Yes.
GOV.UK's UK ETS guidance states it in the imperative: “Your chosen verifier must be accredited by the United Kingdom Accreditation Service (UKAS) to ISO 14065 and the Verification Regulation,” and “the scope of their accreditation must cover the regulated activity you are reporting.” This is a live, mandatory duty — but it is verification of a regulated emissions report under UK ETS, not assurance of a company's wider sustainability disclosures, and the two should never be conflated.
Does SECR require independent verification or assurance?
No.
DESNZ/Defra's Environmental Reporting Guidelines (March 2019) state plainly: “There is no requirement in the legislation for emission and energy use data, or narrative on energy efficiency action to be independently assured,” and separately, “There is no statutory requirement to have your environmental information audited.
The statutory auditor of the financial statements is not required to audit environmental information in the Strategic or Directors' Reports.” Voluntary assurance “is encouraged” as best practice, but no credential of any kind is legally required to prepare a SECR disclosure.
Is ISAE 3410 still the standard for GHG statement assurance?
It is being withdrawn.
The IAASB approved the withdrawal of ISAE 3410 (Assurance Engagements on Greenhouse Gas Statements), announced 8 May 2025, and confirmed the withdrawal “will take effect from the effective date of ISSA 5000” — 15 December 2026.
That date is derived from ISSA 5000's own effective date, not one the IAASB announcement states directly.
Internationally, ISAE 3000 (Revised) also ceases to apply to sustainability engagements from the same date.
Is ISAE (UK) 3000 withdrawn for UK sustainability engagements?
This is genuinely unresolved, and no page should assert otherwise.
As at the most recent check, the FRC's own Assurance Standards page still lists ISAE (UK) 3000 (July 2020) as a current standard, and lists no ISAE (UK) 3410 at all.
ISSA (UK) 5000 ¶11 does say a practitioner performing an ISSA (UK) 5000 engagement “is not required to apply ISAE (UK) 3000,” but that is narrower than a UK withdrawal of ISAE (UK) 3000 itself, which has not been found.
Does the UK ETS verification duty prove UK sustainability assurance is mandatory?
No, and this is the trap worth naming directly.
UK ETS's accredited-verification duty is real and mandatory — but it is verification of a regulated emissions report under a specific EU-derived trading scheme, not assurance of a company's UK SRS or other sustainability disclosures.
No UK entity is under any legal duty to obtain sustainability assurance of its wider disclosures: not under the Companies Act 2006 (s.414CB imposes disclosure duties only), not under UK SRS (the FRC's own FAQ says reporting against UK SRS is not currently mandatory, so there is nothing to assure that is itself mandatory), and not under FCA CP26/5, which expressly proposes no mandatory assurance requirement.
A SECR or UK SRS page should never borrow the UK ETS duty as evidence that assurance generally is required.
What is the difference between ISO 14064-1 and ISO 14064-3?
ISO 14064-1 is the standard an organisation uses to quantify and report its own GHG inventory.
ISO 14064-3 is the standard a third party applies to verify or validate that report once it exists — the verifier's rulebook, not the reporter's.
ISO 14065 sits a level above both: it accredits the bodies that are allowed to perform ISO 14064-3 verification in the first place, which is why a UK ETS verifier must hold UKAS accreditation to ISO 14065 specifically, not merely familiarity with ISO 14064-3.
Related guides & references
UKAS Accreditation: What It Covers, and Doesn’t
The statutory basis for UKAS accreditation, its sixteen accreditation activities, and the rule barring a certifier from also being your consultant
UK SRS Sustainability Assurance
ISSA (UK) 5000, the FRC Interim Register, and why no UK entity is required to assure its sustainability disclosures
GHG Protocol: Scopes and Calculation Methods
The accounting methodology that produces the emissions data a verifier then checks
SECR — Streamlined Energy and Carbon Reporting
Why SECR carries no verification requirement, and what lenders and customers expect anyway
UK SRS Scope 3 Reporting
Comply-or-explain relief and the data quality questions a verifier or assurer will ask first
Carbon Reporting Software
Choosing a system that produces an audit trail a verifier can actually follow
Authority Sources
- UK Emissions Trading Scheme for installations: how to comply
- Environmental Reporting Guidelines including SECR guidance
- ISO 14064-1:2018
- ISO 14064-3:2019
- ISO 14065:2020
- IAASB Announces Withdrawal of ISAE 3410
- ISSA (UK) 5000, General Requirements for Sustainability Assurance Engagements
- FRC Assurance Standards
- Companies Act 2006, section 414CB
- Sustainability Reporting Developments: FAQs
- FCA CP26/5
- DBT–UKAS Memorandum of Understanding 2023