UKAS Accreditation
When It Is Required, and When It Is Not.
Approximately a dozen UKAS-accredited GHG verifiers operate in the United Kingdom. Whether your organisation needs one depends if your report is for a mandatory compliance scheme like UK-ETS. This page sets out where accreditation is mandatory, where it is optional, and what to assess in a verifier in either case.
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Background
What UKAS Accreditation Is
The United Kingdom Accreditation Service is the national accreditation body recognised by government to assess organisations that provide certification, testing and verification services. For greenhouse gas verification specifically, accreditation is granted against ISO 14065 and ISO 17029, which set process and competence requirements for verification bodies.
Accreditation is awarded for a defined scope — specific schemes, specific gases, specific reporting standards — and maintained through periodic surveillance audits. It is a credential held by the verification body, not by an individual engagement or opinion.
What accreditation certifies
- The verification body has documented procedures meeting ISO 14065 / ISO 17029.
- Personnel competence requirements have been independently assessed.
- Impartiality and independence controls are in place and reviewed.
- The body operates within a defined accredited scope, audited at intervals.
What accreditation does not certify
- That any individual verification opinion is materially correct.
- That the lead verifier on your engagement holds particular sector experience.
- That an opinion will be issued more quickly, or at lower cost, than from a non-accredited body.
- That UKAS accredited verification is required for the report you are preparing.
Reference
Where Accreditation Is Required
The table below summarises the verification position for the schemes and standards we are most commonly asked about. It is indicative — scheme rules evolve, and the operator of any specific scheme remains the authoritative source.
| Standard / Scheme | Notes |
|---|---|
| Requires UKAS-accredited verification | |
| UK Emissions Trading Scheme (UK ETS) | Annual emissions reports must be verified by a verifier accredited to ISO 14065 by UKAS for the relevant activity scope. |
| CORSIA (international aviation) | Participating aeroplane operators are required to use verifiers accredited under the CORSIA framework, typically routed through national accreditation bodies including UKAS. |
| Does not require UKAS-accredited verification | |
| Climate Change Agreements (CCA) | Verification arrangements are set by the Environment Agency under the scheme rules. UKAS accreditation is not mandated. |
| Voluntary carbon credit issuance | Verra (VCS), Gold Standard and similar registries each maintain their own approved-verifier lists. UKAS accreditation is one possible route but is not required. |
| ISO 14068-1 carbon neutrality | Third-party verification is expected. UKAS accreditation is not specifically mandated by the standard. |
| Streamlined Energy & Carbon Reporting (SECR) | Qualifying companies must disclose energy use and emissions in their annual report. Independent verification is encouraged but not statutorily required. |
| TCFD- and ISSB-aligned disclosures | Where assurance is required by jurisdiction, the verifier accreditation is typically not prescribed by the framework itself. |
| GHG Protocol Corporate Standard inventory | Organisations may report against the GHG Protocol with or without third-party verification. No accreditation requirement attaches to the framework. |
| ISO 14064-1 inventory development | Inventories may be self-declared. Where third-party verification is sought, the choice of verifier is the organisation's. |
| Science Based Targets initiative (SBTi) | Targets are validated by SBTi. Ongoing inventory verification is encouraged but no specific verifier credential is mandated. |
| CDP disclosure | External verification contributes to higher CDP scoring but the verifier credential is not specified by CDP. |
| Internal GHG management & supply-chain assurance | Verification is commissioned at the organisation's discretion. Methodology, independence and sector evidence become the relevant selection criteria. |
Scheme requirements change. The above is intended as a general orientation. Confirm current verification requirements with the relevant scheme operator before commissioning any engagement.
Verifier Selection
What to Assess in Any Verifier
Whether or not a verifier is UKAS-accredited, the same underlying questions determine whether their opinion will hold up to scrutiny. The following are the controls and credentials we would suggest assessing on any engagement.
Methodology Standard
Verification should be conducted against the GHG Protocol and ISO 14064-3. Ask to see the audit methodology before engagement.
Remote Verification
Remote verification is now standard practice for many engagements. Confirm the verifier is experienced in conducting remote work and conforms to ISO 14064-5:2026, the methodology standard for remote verification of GHG statements.
Independence
A verifier that also offers paid methodology consultation cannot reliably opine on the same work. Do not engage a consultant for verification work as independence is crucial.
Sector Evidence
Ask for examples of completed verifications in your sector. Emissions drivers, data sources and material risks differ markedly between sectors.
Who will actually do the work?
The senior verifier you meet during pre-engagement is often not the person who will conduct your audit. In many firms, the fieldwork is delegated to junior staff with limited experience. Ask who will perform the work and who will sign the opinion — and make sure you are comfortable with the answer.
Findings Process
Ask how findings are documented, how disputes are handled, and what happens if the initial submission does not meet the standard. Process matters as much as credentials.
Buyer Beware
What “Accredited” Actually Covers
UKAS accreditation is granted not as a blanket credential but for a precisely defined scope of activity, set out on the verification body’s accreditation certificate and published on the UKAS register. Two verifiers may both display the UKAS logo while being accredited for entirely different things.
The relevant question for a buyer is therefore not “are they accredited” but “are they accredited for what we are asking them to do.” A surprising number of accreditation certificates, examined against the inventory in front of you, do not pass that test.
A real example from the UKAS public register
“Validation and verification of environmental information to ISO 14065:2020 – Regulated Programmes.”
Product accredited: Verification of carbon dioxide emissions data from Maritime Transport.
That accreditation is properly held. Within its scope — one regulated activity, one gas, one sector, one transport mode — it carries the assurance UKAS is designed to confer.
Outside that scope, it confers nothing. It does not transfer to corporate inventory verification. It does not transfer to multi-entity, multi-country programmes. It does not transfer to value-chain Scope 3 work, nor to the methodological complexity of CHP allocation, refrigerant loss calculation, fleet emissions, half-hourly electricity analysis, spend-based and activity-based Scope 3 across all 15 GHG Protocol categories, or Scope 4 avoided emissions. It does not transfer to any of the work a typical FTSE-listed corporate, NHS trust, local authority or financial-services inventory actually demands.
Two adjacent disciplines, two very different jobs
To make the gap concrete, set the scope above against what a typical corporate GHG engagement actually demands — particularly as the GHG Protocol Actions and Market Instruments (AMI) revision moves towards multi-statement reporting. The same word, “verifier”, conceals two adjacent disciplines that share little methodological ground.
What the accredited scope covers
Maritime fuel CO2 verification
- - One gas: carbon dioxide
- - One activity: fuel combustion in maritime transport
- - One data type: bunker fuel records
- - One regulatory regime: a defined compliance scheme
- - Standardised emission factors per fuel type
- - Single reporting boundary set by the regulator
Properly accredited, properly executed, properly assured — for the work it is accredited for.
What a corporate AMI-aligned engagement demands
Corporate GHG footprinting against the GHG Protocol
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All seven Kyoto gases, GWP-weighted to CO2e
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Scope 1, Scope 2 (location- and market-based), Scope 3 across all 15 categories, and Scope 4 avoided emissions where included
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Multi-entity, multi-country consolidation; control vs equity-share boundary decisions; intra-group eliminations
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Energy attribute certificates (REGOs, GoOs, I-RECs) tested for temporal matching, deliverability and additionality under the AMI market-based statement
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Consequential accounting for the AMI GHG impact statement — avoided emissions, reductions and removals, within and beyond the value chain
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CHP energy allocation, refrigerant loss reconstruction, fleet and homeworking methodologies, half-hourly electricity data, custom and hybrid emission factors
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Scope 3 spend-based, activity-based and supplier-specific approaches across procurement, capital goods, transport, use-phase and end-of-life
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Non-GHG indicators under the AMI fourth statement — intensity metrics, low-carbon procurement percentages, financial contributions to mitigation
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Reporting boundaries set by the GHG Protocol, refined by sector guidance, tested against CDP, SBTi, CSRD, ISO 14064-1 and ISO 14068-1 disclosure rules
The GHG Protocol revision is venturing into methodological ground that an ISO 14065 accreditation, by itself, does not evaluate a verifier against.
Both columns describe legitimate verification work. They are not, however, the same work. The credential earned for the left column does not transfer to the right. More on the GHG Protocol and the AMI multi-statement framework →
Where Carbon Verification Limited focuses
Corporate GHG footprinting. Two decades of practice across 23 economic sectors, with full Scope 1, 2 and 3 coverage including all 15 GHG Protocol Scope 3 categories and, where applicable, Scope 4 avoided emissions. Multi-entity, multi-country programmes. Value-chain emissions complexity. The methodological depth that the foremost corporate disclosure frameworks — CDP, SBTi, CSRD, ISO 14064-1, ISO 14068-1 — actually require.
This is the work we do. It is the work most organisations need verified. And it is the work that compliance-market accreditation, granted for narrow regulated activities, rarely covers.
Agility
Keeping Pace With Evolving Standards
Accredited verification bodies operate within a scope defined and approved by UKAS. Adopting a new methodology, an updated standard, a new sector specialism or a new evidence-gathering technique requires a formal scope-extension submission — a regulated process that takes time to complete. For clients in evolving sectors, in newly regulated supply chains, or with inventories that touch frontier methodological questions, that lag is a real commercial cost.
A more fundamental point sits beneath the procedural one. UKAS accreditation is granted against ISO standards, not against the GHG Protocol. The GHG Protocol Corporate Standard is the foremost international framework for corporate GHG assertions and the framework that underpins CDP, SBTi, CSRD, ISO 14064-1, ISO 14068-1 and almost every other major reporting scheme. There is no UKAS accreditation pathway against the GHG Protocol itself. Accreditation against ISO 14065 confirms a verifier’s procedures conform to a verification body standard. It does not confirm currency with GHG Protocol revisions, correct application of them, or readiness for forthcoming developments such as the GHG Protocol Actions and Market Instruments (AMI) multi-statement framework.
We operate free from accreditation‑imposed constraints. While grounded in the same ISO framework, we are not limited by a fixed scope to defend. By tracking GHG Protocol revisions in real time, we adopt updated standards and methodologies the moment they become operational—ensuring our clients benefit from the most current and authoritative practices available. Four areas where this matters most for clients:
Updated ISO standards
ISO 14064-5:2026, governing remote verification, entered our active methodology on publication. The same approach applies to revisions of ISO 14064-1, ISO 14064-3 and ISO 14066: where the standards body issues an update, we update our procedures against it without waiting for an accreditation scope-extension cycle.
GHG Protocol AMI multi-statement framework
The forthcoming GHG Protocol Actions and Market Instruments (AMI) revision restructures corporate reporting into four distinct statements: a physical GHG inventory; a market-based inventory reflecting qualified contractual instruments such as REGOs, GoOs and I-RECs with temporal matching, deliverability and additionality metadata; a GHG impact statement covering avoided emissions and removals within and beyond the value chain; and non-GHG indicators. Each carries new evidential demands. We are tracking the AMI revision in real time and our verification methodology is being prepared against the four-statement structure ahead of formal adoption.
New sectors and inventory boundaries
Accredited scope is granted sector by sector. A body whose scope was granted for energy generation cannot extend to manufacturing without UKAS approval. We assess each engagement against the team competence requirements of ISO 14066 and accept or decline on that basis. New sector entry is a competence question, not a regulatory one.
New evidence-gathering techniques
Satellite imagery, LiDAR-derived spatial measurement, secure remote sensing platforms, AI-assisted document review and structured data-extraction tools each carry their own risks and benefits. Under ISO 14064-5:2026 we risk-assess each technique and adopt it where fit for purpose. We are not waiting for a scope amendment to use the tools that produce better evidence.
For clients whose inventories sit in evolving methodological territory, agility is not a cosmetic benefit. It is the difference between verification that reflects current best practice and verification that reflects best practice from the last scope-extension cycle.
Accreditation against ISO standards is not accreditation against the GHG Protocol — and it is the GHG Protocol that defines what credible corporate reporting looks like. Helping clients stay aligned with the standard their disclosures are actually being read against is, for us, the more substantive form of assurance.
Cost & Value
Where the Cost of Accreditation Would Fall
UKAS accreditation is a regulatory instrument. It is the appropriate oversight mechanism for verification work that determines a regulated party’s compliance position — emissions allowances under the UK ETS, CORSIA reporting for international aviation, customs duties on imported carbon-intensive goods. In each of these contexts, a regulator depends on the verifier’s opinion, and the costs of independently audited accreditation are properly borne.
In the voluntary market, where no regulator depends on the opinion, the same costs are not extinguished. They are simply transferred to the client, who derives no regulatory benefit from the credential they are funding.
The four cost components
Direct UKAS fees
Initial assessment, annual surveillance, scope extensions and complaint investigations. Paid by the verification body to UKAS year after year and recovered through the verifier’s fee structure.
Internal preparation cost
Management system documentation, internal audits, management review cycles, scope-extension submissions, surveillance preparation and assessor liaison. Typically a multiple of the UKAS fee itself, paid in staff time and capacity displaced from billable verification work.
Client time during witness audits
UKAS assessors observe live verification engagements to confirm verifier competence. A client hosting a witnessed engagement contributes time, accommodates an additional auditor in interviews and data review, and accepts a degree of confidentiality exposure that would not otherwise apply. The witnessed audit assesses the verifier, not the client.
Distorted verification focus
During a witness audit, the verifier’s conduct is necessarily oriented to satisfying the assessor’s procedural checklist. The client’s actual reporting need — the questions that matter for their inventory, their disclosures, their boundary decisions — becomes secondary to the procedural demonstration the assessor expects to observe.
In the compliance market, these costs are justified: a regulator depends on them. In the voluntary market, they are recovered from clients who derive no regulatory benefit from the credential. We have taken the deliberate view that loading a compliance cost onto a non-compliance engagement is not in the client’s interest. We operate in full conformance with the same ISO standards an accredited body works to — ISO 14065, ISO 14066, ISO 14064-3, ISO 14064-5:2026 and ISO/IEC 17029 — and our procedures, impartiality controls, competence framework and findings process are publicly documented on this website and independently reviewable on that basis.
Our Position
Carbon Verification Limited and UKAS Accreditation
Carbon Verification Limited does not verify Emissions Trading Schemes in the mandatory compliance market.
Our work adds the most value in the substantial body of voluntary GHG reporting and assurance. This is our domain with nearly 2 decades of expertise across 23 industry sectors.
What we do undertake
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Voluntary GHG inventory verification against ISO 14064-3
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Internal GHG programme assurance
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Supply chain and Scope 3 emissions verification
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Sustainability report assurance for stakeholder reporting
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Pre-audit and de-risk engagements ahead of formal scheme submission
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Methodology and data quality reviews
What we do not undertake
- UK Emissions Trading Scheme verification
- CORSIA verification for participating aviation operators
If you need an accredited verifier, we will tell you
Where the standard you are reporting against requires a UKAS-accredited verification body, our position is straightforward: we will tell you, and we will direct you to the appropriate route.
If you are uncertain which category your reporting falls into, the reference table above is a useful starting point. A short scoping conversation will resolve most cases definitively.
Specialist expertise. Applied to your organisation.
Our team brings two decades of sector-spanning GHG verification experience to every engagement. Tell us about your organisation and we will assign the right expertise.
no consulting · no commissions · no other commercial interests