Certification · carbon reduction
The Carbon Trust Standard: the Route to Net Zero tiers and the published rules
The Carbon Trust Standard was launched in June 2008 to certify year-on-year carbon reduction, and the organisational certification the Carbon Trust presents today is the Route to Net Zero Standard, launched on 21 February 2022 in three tiers.
The Carbon Trust publishes the technical requirements its verifications follow, and this page sets them out from those documents, dated.
Like every scheme here, it is voluntary: it discharges no UK legal duty.
The name
From the Carbon Trust Standard to the Route to Net Zero Standard
The Carbon Trust Standard was launched in June 2008, with UK government support, to certify that an organisation had measured and actually cut its carbon emissions year on year.
The Carbon Trust’s ten-year retrospective states the design principle in five words: “No exaggeration or embellishment.
No offsetting.”
The name is still the one tender documents and comparison lists use when they ask for “the Carbon Trust Standard”.
The organisational certification the Carbon Trust presents on its site today is the Route to Net Zero Standard, launched on 21 February 2022 with ten pathfinder companies, in three tiers.
No retirement notice for the Carbon Trust Standard was found, and none is asserted here; the page on carbontrust.com that carries the older name, Standard Bearers, reads “Last updated November 2021”.
A buyer who asks for “the Carbon Trust Standard” in 2026 should ask the Carbon Trust, or the supplier, which certification and which tier the certificate is.
- Jun 2008Carbon Trust Standard launched
With UK government support, certifying year-on-year reduction.
- 2012Carbon neutral verification
Offered against PAS 2060.
- Nov 2021Standard Bearers page last updated
The page carrying the older name.
- 21 Feb 2022Route to Net Zero Standard
Three tiers; ten pathfinder companies.
- Sep 2023Carbon neutral verification ends
Existing labels valid until expiry.
- 20 Sep 2024Requirements Part 1 v1.0
Organisational footprint assurance requirements.
The register
One company, four names
The name history is also on the public register: company 06547658, incorporated on 28 March 2008 and active, has carried four names.
It was registered as The Carbon Reduction Standard Company Limited, became The Carbon Trust Standard Company Limited in June 2008, Carbon Trust Certification Limited in October 2011, and Carbon Trust Assurance Limited in August 2017.
The register records when the language changed; it says nothing about the quality of the work, and renaming a subsidiary is routine.
Anyone can check the record at Companies House, which is the place to confirm the legal entity behind any certificate.
| Name | Period |
|---|---|
| The Carbon Reduction Standard Company Limited | 28 Mar 2008 – 17 Jun 2008 |
| The Carbon Trust Standard Company Limited | 17 Jun 2008 – 17 Oct 2011 |
| Carbon Trust Certification Limited | 17 Oct 2011 – 16 Aug 2017 |
| Carbon Trust Assurance Limited | Since 16 Aug 2017; active |
The live certification
Route to Net Zero, in three tiers
In the Carbon Trust’s words: “We have developed 3 certification tiers to guide you on your journey to Net Zero.
As you progress through the levels, the qualifying requirements become more challenging and cover more aspects of carbon management.”
| Tier | Reductions | Target | Management practices |
|---|---|---|---|
| Taking Action | Historical reductions in operational emissions | A GHG emissions reduction target | Foundational CO2e management practices |
| Advancing | Science-aligned reductions in emissions | A science-aligned reduction target | Advancing CO2e management practices |
| Leading | 1.5°C-aligned reductions in emissions | A Net Zero target | Leading CO2e management practices |
Each tier’s certificate covers three things — reductions, a target and management practices — and the requirements rise with the tier.
The Taking Action target is “a GHG emissions reduction target” with no stated ambition level, Advancing requires science-aligned reductions and a science-aligned target, and Leading requires 1.5°C-aligned reductions and a Net Zero target.
The certificate name is the same at every tier, so the tier is the part of a claim that says which of the three was met.
At launch the Carbon Trust described a mechanism limiting how long a company may stay at a lower tier; no Carbon Trust page stating its terms was found, so no number of periods is given here.
“Science-aligned” and “1.5°C-aligned” refer to target-setting methods validated by the Science Based Targets initiative; the guide to setting science-based targets explains that route.
The published requirements
Requirements for assurance, version 1.0
The Carbon Trust publishes the technical requirements its organisational footprint verifications follow: Organisational carbon footprints: Requirements for assurance, Part 1: Technical, version 1.0, issued on 20 September 2024.
The document states its own audience: it “is intended to be used by both the Carbon Trust and external parties”, so a customer or a buyer can read what conformity requires.
Conformity is required to five external standards: the GHG Protocol Corporate Accounting and Reporting Standard, the Scope 2 Guidance, the Corporate Value Chain (Scope 3) Standard, the Land Sector and Removals Guidance, and PCAF’s financed emissions standard where relevant.
The boundary rule is precise: the organisation “shall choose the operational verification boundary (including Scope 1 and 2 emissions at a minimum), or shall have already a verified Scope 1 and 2 footprint where the organisation wishes for a Scope 3 footprint to be verified”.
Scope 3 is therefore verifiable and optional, and a certificate does not state on its face which boundary was verified.
The document flags its own provisional part: the section on the Land Sector and Removals Guidance will be rewritten when that guidance is finally published.
There is a matching Part 2 for claims, and an equivalent pair for product carbon footprints, of which Product carbon footprints, Part 2, version 3.2 carries the claim rules below.
The GHG Protocol guide and the Scope 3 guide explain the accounting the requirements rest on, and Scope 3 under UK SRS covers where value-chain emissions meet the UK standards.
| Part 1 covers | For example |
|---|---|
| Organisational boundary | Equity share, financial control or operational control |
| Operational verification boundary | Scope 1 and 2 at minimum; Scope 3 optional |
| Data and factors | Emission factors, Scope 2 treatment, allocation, primary and secondary data |
| Land and biogenic carbon | Land-based emissions and removals; biogenic carbon |
| Baselines | Base year and rebaselining policy |
| Materiality | Materiality and cut-off criteria |
| Verification | Evidence requests, site visits, re-verification of later years |
How a verification runs
Before, during and after a Carbon Trust verification
Part 1 sets out the process as well as the accounting rules.
Everything below is from version 1.0 of that document.
| Stage | What Part 1 requires |
|---|---|
| Before the engagement | Confirm the objective, the intended claim, site or organisational verification, the consolidation approach, the organisational and operational verification boundaries, exclusions, materiality, sites, key parameters, time period, footprinting tool and data sources |
| Tools | Any footprinting tool may be used; a third-party tool must conform to the GHG Protocol, be third-party assured or accessible, and allow the data to be traced |
| Site-level option | A single site may be verified, with or without the logo; without it, the boundary must cover all the operational emissions of that site and technical committee approval is requested through the Client Manager |
| First stage | Calculation data input: the footprint, its data, the methodology, any other third-party audits and sufficient evidence, submitted as aggregated data before verification |
| Second stage | Transaction-level data and compliance: transaction listings, sampled invoices, a site visit and interviews |
| Findings | The document defines nonconformities (NC) and opportunities for improvement (OFI), and distinguishes an exclusion from an omission |
| Later years | Re-verification of subsequent years is covered by its own section |
Part 1 defines the minimum requirements for verifying an organisational footprint “without the use of the Carbon Trust organisational verification logo”; a claim with the logo also has to meet Part 2.
Organisations must use the latest version of the requirements, unless the project commences within six months of the contract being signed.
It names the Carbon Trust’s own Organisational Footprinting Tool and Value Chain Model as approved footprinting tools, while allowing any tool that meets its requirements.
The data the first stage asks for is the same data a company needs for SECR or a Carbon Reduction Plan, which is why the work overlaps even though the obligations are separate.
Claims
What counts as a reduction, and what a claim says
| Rule | What the requirements say |
|---|---|
| Offsets | “Reductions which are not eligible for the claim: • Use of offsets.” |
| Reductions outside the organisation’s control | May be claimed, for example grid decarbonisation, but must be identified as such |
| Claim periods | Two years for achieved reductions and two for planned reductions; one year for a validated forward-looking claim |
| From the third verification | A footprint that has not increased may be accepted in place of a reduction, with written justification and evidence of actions taken in the previous 24 months |
| Named organisational claims | “Reduced” and “reduced and climate projects funded” |
| Logo | A footprint may be verified without the right to use the logo |
The offsets exclusion carries the 2008 principle into the current documents: a reduction claim rests on actions within the organisation’s control or influence.
“Reduced and climate projects funded” states the funding of climate projects as a separate fact beside the reduction, rather than folding it into the reduction.
The third-verification clause applies only from the third verification, only where the footprint has not risen, and only with written justification and evidence of actions over the previous 24 months.
A verification letter is a statement about the footprint; a label licence is permission to make a claim in public with usage guidelines attached, and the requirements treat them differently.
The Carbon Trust’s label portfolio covers a product carbon footprint label, an assured model label, an organisational carbon footprint label and participation in Amazon’s Climate Pledge Friendly programme, with a public directory of labelled products.
Read a claim
What a particular claim covers
A Carbon Trust claim is made of four parts: the tier or label, the verified boundary, the kind of claim, and which verification it is.
The tool beside this text takes each part in turn and sets out the Carbon Trust rule that applies to it, with the document it comes from.
It interprets nothing beyond those documents: where a claim leaves a part out, the tool says which question to ask.
The same questions work for a supplier’s certificate in a tender and for a company’s own claim before it is published.
The ESG reporting guide covers how such a claim is usually presented alongside wider disclosures, and the carbon reporting guide covers the UK regimes that sit beside it.
Read a Carbon Trust claim
Describe the claim you are reading. Each answer adds the Carbon Trust rule that applies to it.
The Carbon Trust’s own published terms, read 1 October 2026.
Nothing you choose is saved.
Carbon neutral
Carbon neutral verification ended in September 2023
The Carbon Trust offered carbon neutral verification from 2012, against PAS 2060, and its verification page now states that it stopped offering it in September 2023.
It describes the change as moving the verification and label towards “a greater emphasis on reduction, more rigorous and ambitious requirements and language to enhance clarity of meaning”.
A Carbon Neutral label already on a product remains valid until its verification period expires, so seeing one is not evidence of a false claim.
The standard underneath has since gone too: BSI stopped delivering the PAS 2060 scheme on 1 January 2025 and withdrew it at the end of 2025, and UKAS set 31 December 2025 as the migration deadline.
Its successor, ISO 14068-1:2023, was itself withdrawn by ISO on 11 September 2026 and is being replaced by ISO 14068:2026, Climate change management — Carbon neutrality.
The PAS 2060 and ISO 14068 guide sets out the dates, and the carbon offset consultant guide covers advice on offsetting separately.
“From September 2023 we are no longer offering carbon neutral verification.
You may still see products in the market with the Carbon Neutral label; this label is valid as it applies to the products or packaging that have been verified as Carbon Neutral, until the verification period expires.”
The Carbon Trust, Carbon neutral verification, read 1 October 2026
Who verifies
The scheme owner, and the bodies it approves
The Carbon Trust’s scheme-owner statement says its Carbon Label Conformity Assessment System “is owned by Carbon Trust Scheme Owner Ltd, a legally independent subsidiary of the Carbon Trust Group”.
Verification against the scheme requirements “is conducted by CT Assurance Ltd or other CT SO Ltd approved Conformity Assessment Bodies”.
Approved bodies must “demonstrate accreditation (or a commitment to achieving accreditation) to ISO/IEC 17029, ISO 14065 and ISO 14066” from a national accreditation body that signs the International Accreditation Forum’s Multilateral Recognition Arrangement.
The three standards do different jobs: ISO/IEC 17029 covers validation and verification bodies generally, ISO 14065 applies it to environmental information, and ISO 14066 sets competence requirements for verification teams.
The statement’s wording includes bodies with “a commitment to achieving accreditation”, so whether a particular body is accredited is a question for the UKAS directory, not for the scheme document.
The document also describes training, pilot verifications and ongoing oversight for approved bodies.
Accreditation
What accreditation means for a verification body
UKAS calls accreditation and certification “two closely related but distinct steps on the quality assurance ladder”: an organisation is certified, and the body that certifies or verifies it is accredited.
The regime for greenhouse gas verifiers moved recently: UKAS required validation and verification bodies accredited to ISO 14065 for greenhouse gas assertions to transition to ISO/IEC 17029 by 30 June 2024.
Accreditation programmes under the 2013 edition of ISO 14065 ran only until that date, so “accredited to ISO 14065:2013” is not a current UK credential for any body.
The check takes one search: name the body that issued the verification and look it up in the UKAS directory, which shows whether it is accredited and for what scope.
The UKAS accreditation page explains the directory and the legal basis, and sustainability assurance covers assurance of reported disclosures, which is a different engagement.
Targets
The SBTi versions the upper tiers refer to
The Advancing and Leading tiers are defined by reference to science-aligned and 1.5°C-aligned targets, so the version of the SBTi standard in force matters to what a tier means at a given date.
The SBTi published its Corporate Net-Zero Standard Version 2.0 on 11 June 2026, and V1.3.1 remains the operative standard for submissions today.
Validations against V2.0 open on 1 February 2027, companies may submit under either version until 31 January 2028, and V2.0 is mandatory after that.
The Carbon Trust publishes its own briefing on science-based targets, and its own Carbon Reduction Plan in the PPN 006 format.
The SBTi V2 guide sets out what the new version changes, and the climate transition plan guide covers the plan a net zero target sits inside.
- 11 Jun 2026CNZS V2.0 published
Not yet usable for validation.
- 1 Feb 2027Validations open against V2.0
Companies may submit under V1.3.1 or V2.0.
- 31 Jan 2028V1.3.1 submissions close
V2.0 mandatory thereafter.
Is it a legal requirement?
Does it satisfy any UK legal duty? No — it is voluntary
A Carbon Trust certificate, verification or label is voluntary, and it discharges no UK legal duty.
SECR and the Energy Savings Opportunity Scheme are statutory, with their own qualification tests and deadlines, and no certificate satisfies either.
Central government bidders on in-scope contracts are asked for a Carbon Reduction Plan under PPN 006 in a prescribed form; a certificate is not that plan, and PPN 06/21 still governs procurements begun before 24 February 2025.
A listed company reporting against UK SRS under the FCA’s final rules reports on a comply-or-explain basis for periods beginning on or after 1 January 2027; the UK SRS reporting guide covers what that means.
How a certificate is described to consumers is governed in the UK by the misleading-practices rules of the Digital Markets, Competition and Consumers Act 2024, with the CMA’s Green Claims Code as guidance, and the anti-greenwashing rule applies to FCA-authorised firms.
In the EU, Directive (EU) 2024/825 has applied to sustainability labels and offset-based product claims since 27 September 2026, and the Carbon Trust’s scheme-owner statement is its published response.
Does a Carbon Trust certificate satisfy a UK legal duty?
No. A Carbon Trust certificate or label is voluntary, and it discharges none of the duties below.
Choose a duty to see why, and the provision behind the answer.
SECR is a disclosure a qualifying company makes in its own directors’ report. A Carbon Trust certificate or label is not that disclosure and does not change whether a company is in scope; the guidance adds that there is no statutory requirement to have the environmental information audited.
SI 2018/1155, amending Schedule 7 to SI 2008/410 · SI 2018/1155; Environmental Reporting Guidelines (March 2019) Ch.1 Action iv
Answers rest on the provisions named in each row.
Nothing you choose is saved.
Before relying on one
Six questions for any Carbon Trust claim
| Ask | Why, from the published rules |
|---|---|
| Which certification and which tier? | Route to Net Zero has three tiers with different targets |
| Over what period? | Claim periods are fixed in the requirements |
| Which boundary was verified? | Scope 1 and 2 is the minimum; Scope 3 is optional |
| A verification, or a label licence? | A footprint can be verified without the right to use the logo |
| If it says carbon neutral, from when? | Carbon neutral verification has not been offered since September 2023 |
| Which body verified it? | Approved bodies may be accredited or committed to accreditation; check the UKAS directory |
Each answer is available from the certificate, the verification statement or the published requirements.
Questions about the measurement itself belong with the footprint: the carbon accounting and Scopes 1, 2 and 3 guides explain the terms, and product carbon standards cover product labels.
Where a company holds more than one mark, each answers its own question: see ISO 14001, B Corp certification and Planet Mark for their terms.
Related guides
Where the footprint comes from and goes
Carbon accounting
How the footprint behind a verification is built.
Scopes 1, 2 and 3
The boundary terms the requirements use.
Scope 3 emissions
The optional part of the verified boundary.
Scope 3 under UK SRS
Where value-chain emissions meet the UK standards.
The GHG Protocol
The accounting standard the requirements are built on.
Product carbon standards
LCA and product footprint standards behind a label.
PAS 2060 and ISO 14068
The withdrawn standard and its successor.
Setting science-based targets
The route to the targets the upper tiers reference.
SBTi net-zero standard V2
What changes, and when it can be used.
Climate transition plans
The plan a Leading-tier target sits inside.
ESG questionnaires
Where a certificate is asked for.
ESG criteria
What a buyer scores.
For frameworks and advice around certification, see ESG frameworks in the UK, choosing a net zero consultant, global sustainability standards and the UK regulation timeline.
The documents
The Carbon Trust, the standards and the claims rules
The Carbon Trust
- The Carbon TrustThe Carbon Trust
- The Carbon TrustCarbon footprint labelling and the label directory
- The Carbon TrustBriefing: science-based targets
- The Carbon TrustCarbon Reduction Plan (2023)
- Companies HouseFind and update company information
Measurement and targets
- GHG ProtocolCorporate Accounting and Reporting Standard
- GHG ProtocolScope 2 Guidance
- GHG ProtocolCorporate Value Chain (Scope 3) Standard
- PCAFGlobal GHG Accounting and Reporting Standard
- ISOISO 14064-1 — organisational GHG quantification
- GOV.UK (DESNZ)Government conversion factors for company reporting
- SBTiScience Based Targets initiative
- SBTiStandards and guidance
- SBTiCompanies taking action
Accreditation, carbon neutrality and claims
- UKASUKAS — the UK national accreditation body
- IAFInternational Accreditation Forum
- UKASISO 14068-1 migration from PAS 2060 (technical bulletin)
- ISOISO 14068-1:2023 — catalogue record (withdrawn 11 September 2026)
- ISOISO 14001 — environmental management systems
- ISOISO/IEC 17021-1 — management system certification bodies
- GOV.UK (CMA)Green Claims Code
- CMAMisleading environmental claims — case page
- ASAEnvironmental claims — advertising rulings
- GOV.UK (DESNZ)Environmental reporting guidelines, including SECR
- GOV.UKEnergy Savings Opportunity Scheme (ESOS)
- Cabinet OfficePPN 06/21 — Carbon Reduction Plans (procurements before 24 February 2025)
Frequently asked
The Carbon Trust Standard, answered
What is the Carbon Trust Standard?
The Carbon Trust Standard was launched in June 2008, with UK government support, to certify that an organisation had measured and reduced its carbon emissions year on year, without offsetting.
The certification the Carbon Trust presents today for organisations is the Route to Net Zero Standard, launched on 21 February 2022.
Is the Carbon Trust Standard still available?
The Carbon Trust has not published a retirement notice that could be found, so ask the Carbon Trust.
Its current site presents the Route to Net Zero Standard as the organisational certification, and the page carrying the Carbon Trust Standard name reads “Last updated November 2021”.
What are the three Route to Net Zero tiers?
Taking Action covers historical reductions in operational emissions, a GHG emissions reduction target and foundational CO2e management practices.
Advancing covers science-aligned reductions, a science-aligned reduction target and advancing practices.
Leading covers 1.5°C-aligned reductions, a Net Zero target and leading practices.
Does the Carbon Trust publish its certification requirements?
Yes.
Organisational carbon footprints: Requirements for assurance, Part 1: Technical, version 1.0, issued 20 September 2024, states that it is intended to be used by both the Carbon Trust and external parties.
There is a Part 2 for claims and an equivalent pair for product footprints.
Does Carbon Trust verification cover Scope 3?
Optionally.
The requirements set Scope 1 and 2 as the minimum operational verification boundary; an organisation may have a Scope 3 footprint verified where Scope 1 and 2 are verified too.
Do carbon offsets count towards a Carbon Trust reduction claim?
No. The product requirements list use of offsets among reductions not eligible for a claim.
Reductions from actions outside the organisation’s control, such as grid decarbonisation, may be claimed but must be identified as such.
Does the Carbon Trust still do carbon neutral verification?
No. The Carbon Trust says that from September 2023 it is no longer offering carbon neutral verification, which it had offered since 2012 against PAS 2060.
Products already carrying the Carbon Neutral label remain validly labelled until their verification period expires.
Who verifies against the Carbon Trust’s schemes?
The Carbon Trust’s scheme-owner statement says its Carbon Label Conformity Assessment System is owned by Carbon Trust Scheme Owner Ltd, a legally independent subsidiary, and that verification is by CT Assurance Ltd or other approved conformity assessment bodies, which must demonstrate accreditation, or a commitment to achieving it, to ISO/IEC 17029, ISO 14065 and ISO 14066.
Is Carbon Trust certification a legal requirement?
No. It is voluntary and discharges no UK legal duty: not SECR, not ESOS, not the FCA’s UK SRS listing rules, and it is not a Carbon Reduction Plan under PPN 006.
What does a Carbon Trust label claim say?
For organisational footprints the named claims are “reduced” and “reduced and climate projects funded”.
A footprint can also be verified without the right to use the logo, so a verification and a label licence are different entitlements.
How long does a Carbon Trust reduction claim last?
Under the product requirements, claim periods are two years for achieved reductions and two for planned reductions, and one year for a validated forward-looking claim.
Which SBTi standard do the upper tiers refer to?
The Advancing and Leading tiers refer to science-aligned and 1.5°C-aligned targets.
The SBTi published Corporate Net-Zero Standard V2.0 on 11 June 2026; V1.3.1 remains the operative standard until validations open against V2.0 on 1 February 2027, and V2.0 becomes mandatory after 31 January 2028.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner.
Secondary commentary is never the source for a number.
- The Carbon TrustRoute to Net Zero Standard (read 1 October 2026)
The three certification tiers and what each certificate covers, in the Carbon Trust’s words.
- The Carbon TrustThe Carbon Trust launches new Route to Net Zero Standard (21 February 2022)
The launch date and the ten pathfinder companies.
- The Carbon TrustThe Carbon Trust Standard: looking back over a decade of real reductions
The 2008 Standard and its design principle, “No exaggeration or embellishment. No offsetting.”
- The Carbon TrustStandard Bearers — the Carbon Trust Standard page (“Last updated November 2021”)
The page that carries the Carbon Trust Standard name.
- The Carbon TrustOrganisational carbon footprints: Requirements for assurance, Part 1: Technical (v1.0, 20 September 2024)
Boundary, conformity standards, verification stages and re-verification.
- The Carbon TrustProduct carbon footprints: Requirements for assurance, Part 2 (v3.2)
Claim eligibility, the offsets exclusion and the claim periods.
- The Carbon TrustCarbon neutral verification (read 1 October 2026)
“From September 2023 we are no longer offering carbon neutral verification.”
- Carbon Trust Scheme Owner LtdScheme owner statement on the Empowering Consumers Directive
The scheme-owner structure and the approval bar for conformity assessment bodies.
- Companies HouseCarbon Trust Assurance Limited, company 06547658 — overview and previous names
The entity’s name history, read at the register.
- UKASValidation and verification body accreditation
The transition of GHG verification bodies from ISO 14065 to ISO/IEC 17029 by 30 June 2024.
- ISOISO/IEC 17029:2019 — validation and verification bodies
The general standard for verification bodies.
- ISOISO 14065:2020 — bodies validating and verifying environmental information
The sector application of ISO/IEC 17029, confirmed in 2026.
- ISOISO 14066:2023 — competence requirements for verification teams
The third standard in the approval bar.
- SBTiCorporate Net-Zero Standard Version 2.0
Published 11 June 2026; V1.3.1 operative until validations open against V2.0.
- BSIBS ISO 14068-1:2023 and the PAS 2060 withdrawal rule
The carbon-neutrality standard the Carbon Trust’s former verification ran against, and its successor.
- EUR-LexDirective (EU) 2024/825 — empowering consumers for the green transition
EU rules on sustainability labels and offset-based claims, applying from 27 September 2026.