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London Reporting Academy California SB 253 · Climate Corporate Data Accountability Act · Disclosure SB253-ASSURANCE

Third-party assurance

SB253-ASSURANCE · mandatory · narrative disclosure

For the first reporting year, check CARB guidance on reporting from data already held, with or without assurance. Record the assurance actually obtained. First-year enforcement discretion is not a permanent exemption.

Disclosure focus

The practical focus is on coverage and credibility, not just the fact that assurance exists. A useful explanation should help a reader understand whether the assurance covered the organisation’s full operations or only certain entities, sites, or emissions scopes, and whether the review was designed to support confidence in the reported figures as a whole or only in a narrower subset.

This LRA educational guidance supports disclosure preparation. For the exact requirements, always refer to the official CARB source.

Prepare

What to collect before drafting

Tick each field as the evidence lands. Owners are the teams that usually hold the source files.

  • Scope 1 and 2 coverage

    Sustainability reporting / Finance

    State the assurance level applied to the emissions figures for direct emissions and purchased-energy emissions.

    Evidence Assurance statement or report, plus the final emissions schedule showing which scopes were covered.

    Watch for Scope 1 and Scope 2 are mixed up, or the assurance level is stated for the wrong emissions boundary.

  • Assurance caveats

    Sustainability reporting / Legal

    Capture any stated limits, exceptions, or reservations attached to the assurance work.

    Evidence Assurance report wording, including any qualifications, exclusions, or scope restrictions.

    Watch for A qualification in the assurance report is omitted or softened, so the published note does not match the provider’s caveat.

  • Assurance conclusion

    Sustainability reporting / Finance

    Record the provider’s overall conclusion on the assured information, using the exact outcome they reached.

    Evidence Signed assurance opinion or conclusion section from the provider’s report.

    Watch for The conclusion is paraphrased into a different outcome, or the final wording does not reconcile to the signed assurance report.

  • Assurance provider

    Procurement / Sustainability reporting

    Identify the external party that carried out the assurance work and issued the statement.

    Evidence Engagement letter, provider letterhead, or signed assurance report naming the firm or practitioner.

    Watch for The named provider does not match the signed report or engagement letter, or an internal reviewer is listed instead of the external assurer.

  • Scope 3 assurance status

    Sustainability reporting / Supply chain

    Show whether the value-chain emissions information was assured, and if so, the status or extent of that assurance.

    Evidence Assurance report and the Scope 3 inventory or disclosure table showing the assured portion.

    Watch for The status is reported for the full value-chain inventory when only part of it was assured, or the assured and unassured parts are not separated.

  • Assurance method standard

    Sustainability reporting / Finance

    Name the assurance framework or method the provider used for the engagement.

    Evidence Assurance report, engagement terms, or provider methodology statement naming the standard applied.

    Watch for The assurance method is taken from a template or prior year and does not match the standard actually cited in the provider’s report.

Before you start

  • Have you pinned down which Scope 1 and Scope 2 figures will be covered, and which reporting period they come from?
  • Can you point each number back to a source record or working paper that someone else could follow?
  • Have you decided whether Scope 3 is being checked at all, or left outside this review?
  • Do you know which external reviewer will sign off, and whether they are independent from the organisation?
  • Have you settled the level of assurance, the method used, and any limits or caveats that came with the review?
  • Do you know the final conclusion the reviewer gave, in the exact form you will carry into the report?
+ Show SB253-ASSURANCE sub-elements (LRA working checklist)

How to prepare it

For the first reporting year, check CARB guidance on reporting from data already held, with or without assurance. Record the assurance actually obtained. First-year enforcement discretion is not a permanent exemption.
Confirm who carried out the work and what method they used. Record the external assurance provider and the assurance framework or approach named in the report, using the same source documents throughout.
Gather the supporting material behind the assurance result. This should include the evidence the provider relied on, plus the underlying records needed to support the stated level, status, and conclusion.
Prepare the disclosure text itself in clear business language. Set out the assurance level for Scope 1 and Scope 2, the conclusion reached, and any note on Scope 3 status, making sure each item matches the source evidence.
Add any caveats or boundaries that affect how the assurance should be read. If the provider set limits, exceptions, or qualifications, describe them plainly and keep them tied to the relevant part of the assurance statement.
Before finalising, check the disclosure against the official source and the provider’s report. Make sure the wording, figures, and narrative are consistent, and that nothing material has been omitted or changed in translation.

Request the data

Request the assurance pack from Finance

Translate the disclosure into an internal business question — then adapt it to your organisation's own language.

What third-party assurance evidence do we have for our Scope 1, Scope 2, and any Scope 3 emissions reporting, and who provided it?

Use your organisation’s own labels first, then map them to the reporting fields. For example, ask for the assurance letter, review note, or external verification pack in the terms your team already uses, rather than using framework wording in the request.

Weak request

Please provide the third-party assurance evidence for the disclosure.

Why it fails: This is too framework-led and vague. It does not tell the owner which reporting period, which emissions areas, which document type, or which caveats matter, so the response may be incomplete or hard to use.

Better request

Please send the signed external assurance or verification document for [reporting period] covering our emissions reporting, plus the provider name, what parts of the inventory it covers, the conclusion, and any limitations or qualifications. Use your team’s usual document names and include the file link.

Formal email template
Subject: Request for assurance evidence for emissions reporting

Hi [name],

We are preparing the disclosure pack for [reporting period]. Please send the latest external assurance or verification evidence covering our emissions reporting, including:
- the provider name;
- the emissions areas covered;
- the assurance statement or report;
- any limitations, qualifications, or exceptions noted by the provider; and
- the basis used in the provider’s conclusion.

Please also confirm the file location and the internal contact who can answer follow-up questions.

If there are multiple documents, please send the final signed version and any supporting notes we should keep on file.

Please adapt this to your organisation’s own terms and check the source material before sign-off.

Thanks,
[preparer name]
Short Teams / Slack version
Hi [name] — could you send the latest external assurance/verification pack for [reporting period] for our emissions reporting? Please include the provider name, what it covers, any caveats, the conclusion, and the file link. Please use your team’s usual document names and check the source material before sign-off. Thanks.

Industry examples

Manufacturing

Context. A plant-based group has external review of its emissions inventory prepared by a specialist verifier.

Adapted request. Please send the latest verification report for [reporting period] covering plant fuel use, purchased electricity, and any other emissions areas reviewed, plus the verifier name, conclusion, and any limitations noted. Use the document name your team uses internally.

Example response. Verification report dated [date], verifier [name], covers Scope 1 and Scope 2 for all sites in the group, conclusion states [summary], with one limitation noted for [site]. File stored at [link].

Retail / Consumer Goods

Context. A multi-site business has assurance over group emissions data prepared through the sustainability reporting team.

Adapted request. Please share the external assurance pack for [reporting period] for the group emissions file, including the assurance statement, the provider, whether Scope 3 was included, and any exceptions or caveats. Please use the same file names your team already uses.

Example response. Assurance statement from [provider], dated [date], covers Scope 1 and Scope 2 and selected Scope 3 categories, conclusion [summary], with no material exceptions noted. Supporting files saved in [location].

Draft your disclosure

Notes that turn data into a disclosure

LRA training templates — adapt them to your organisation, and check the official source before sign-off.

Method note

State which emissions areas were reviewed, who carried out the external check, what assurance framework they used, and whether any limits or qualifications were attached to the review.

Context note

Explain what the assurance result means for readers by clarifying the level of confidence reached for the reported emissions data and whether Scope 3 was included or left outside the review.

Fluctuation statement

If the assurance outcome changed from the prior period, note whether the shift reflects a different review scope, a change in the external reviewer or framework, or the removal or addition of any qualifications.

Content index entry

SB253-ASSURANCE Third-party assurance — [location / page] / [notes]

Download Centre

Preparation tools & forms

Download preparation tools for SB253-ASSURANCE with free verified email access for 24 hours. Source-report links remain public.

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Check

For each claim, check the evidence

  • We obtained the public assurance pack for the emissions figures, and it names the external reviewer.

    Risk The assurer checks whether the published pack is complete and whether the named reviewer can be matched to the engagement.

    Evidence to check Published assurance report; cover page or signature page showing the reviewer’s name; final public filing set.

  • For the year in question, we had the external review carried out at the required level for the first two emissions scopes.

    Risk The assurer probes whether the engagement level actually matches the level expected for that reporting year, rather than a lower or different form of review.

    Evidence to check Engagement letter; assurance report wording on level applied; internal reporting calendar or compliance checklist for the year.

  • Where the review noted any caveats, we kept those points visible in the published material rather than summarising them away.

    Risk The assurer checks whether any restrictions, exceptions, or caveats were fully carried through into the disclosure.

    Evidence to check Assurance report; redline of the public disclosure; management response or issue log showing how caveats were handled.

  • The assurance report we published includes the reviewer’s overall view and makes clear whether there were any caveats or not.

    Risk The assurer probes whether the report states a conclusion and whether the presence or absence of caveats is unambiguous.

    Evidence to check Final assurance report; publication pack; sign-off memo confirming the report version released to the public.

  • We used an outside reviewer, not an in-house team, for the assurance work.

    Risk The assurer checks whether the reviewer was genuinely external to the reporting entity and its connected entities.

    Evidence to check Provider contract; independence declaration; corporate relationship checks; conflict-of-interest records.

  • Before appointing the reviewer, we checked that they had relevant emissions-assurance experience and the capability to complete the work properly.

    Risk The assurer probes whether the reviewer had the right competence, capacity, and practical ability for the engagement.

    Evidence to check Provider credentials; CVs or team biographies; proposal or tender documents; competence assessment notes.

Evidence pack to prepare

Common reporting gaps

  • The information is presented without a date or as-at point.
  • The scope or boundary of the statement is left undefined.
  • Key terms are used inconsistently across the report.
  • Material changes since the previous period are not disclosed.
  • Assertions are made without supporting detail or a source record.
  • Boilerplate is used that does not actually answer what is asked.

Where drafts go wrong

Mistakes to avoid and where judgement is needed

The left column is what preparers get wrong while collecting; the right column is where you will have to make and explain a judgement.

Mistakes to avoid

  • Wrong owner askedThe team chases the sustainability lead for assurance evidence when the audit, finance, or external provider team actually holds the working papers and sign-off trail.
  • Framework labels used too earlyPeople ask for the data in disclosure language instead of the organisation’s own process terms, so the source team cannot map the request to its normal records.
  • Scope not pinned downThe collector never states whether the check covers only Scope 1 and Scope 2 or also the Scope 3 status field, so different teams send different slices of data.
  • Wrong reporting periodEvidence is pulled from a different cut-off date or reporting window than the one used for the disclosure pack, which makes the assurance record inconsistent with the rest of the filing.
+ Show 5 more

Judgement needed

  • What counts as the covered emissions set after a buy-in or saleIf the reporting boundary changed during the year, explain which sites, entities and activity data were included in the assurance work and how you dealt with any opening or closing-period changes.
  • Using different country methods for the same activityWhere local data systems or calculation methods differ across countries, state which approach was used for each location and why the final assurance view still gives a like-for-like picture.
  • Borderline cases for people, assets or operations near the boundaryFor items close to the inclusion line, set out the rule you used to include or leave them out and disclose any material judgement made by management or the assurer.
  • Choosing the cut-off date and data basisIf the assurance work uses a different timing basis, reporting date or data cut-off from the underlying operational records, explain the basis chosen and any effect on comparability.
+ Show 4 more

Examples

How it reads on the page

Synthetic, written by LRA — not from a company report, not text from any standard.

Illustrative (synthetic) example — manufacturing

We have included this synthetic example to show how our group might describe external review of its climate data. For the year ended 31 December 2025, an independent assurance firm reviewed our Scope 1 and Scope 2 emissions at a limited level of assurance, using ISAE 3000 (Revised) together with ISAE 3410; the conclusion was that nothing came to the reviewer’s attention to suggest the figures were materially misstated. Scope 3 was not covered in the same review, and the report noted a few boundaries and estimation points that narrowed the work performed.

Illustrative only: this example shows how a reporter can explain who performed the review, what level of confidence was reached for direct and purchased-energy emissions, which framework was used, whether indirect value-chain emissions were included, and any caveats on scope or methods.

Illustrative (synthetic) example — transport and logistics

This synthetic example shows one way we might report our external check of emissions information. For 2025, an independent third party provided reasonable assurance over our Scope 1 and Scope 2 figures under ISAE 3000 (Revised), and the conclusion was positive with no material issues identified; however, the reviewer set out a few qualifications linked to data gaps at two sites and excluded Scope 3 from the engagement.

Illustrative only: this example demonstrates a different sector voice while still covering the reviewer, the confidence level for direct and purchased-energy emissions, the assurance framework, the outcome, the limits noted, and the fact that value-chain emissions were outside the review.

Quality ladder

  • Basic

    An independent reviewer gave our Scope 1 and Scope 2 emissions a limited assurance opinion.

  • Better

    An external assurance firm gave our Scope 1 and Scope 2 emissions limited assurance under ISAE 3000, and it noted no material limitations.

  • Best

    An independent assurance provider reviewed our Scope 1 and Scope 2 emissions for the year ended 31 December 2025 under ISAE 3000 and issued limited assurance; Scope 3 was not covered, and the main reason for the unchanged result was that our data collection controls stayed consistent through the period.

Check your understanding

Scenarios to work through

A reporting team has a signed assurance report for its Scope 1 and Scope 2 figures. The report names the external reviewer, states the level of review reached, and includes a conclusion, but the team is unsure whether to mention that the reviewer also noted a scope restriction on one site visit.

QWhat should the preparer decide to include when summarising the external review for this disclosure?
Reveal model answer →

An organisation has obtained external review for its direct emissions and purchased electricity data, but its Scope 3 work is still being checked internally and no outside review has started. The draft narrative currently says only that the wider value-chain figures are “under review”.

QHow should the preparer describe the position on Scope 3 assurance?
Reveal model answer →

A company engaged a specialist firm to review its emissions data, but the draft note does not say whether that firm was independent. The preparer argues that the firm’s name and report title are enough because the reviewer is well known in the market.

QWhat judgement should the preparer make about identifying the assurance provider?
Reveal model answer →

The assurance report says the emissions data were reviewed using a recognised assurance framework and gives a conclusion with a qualification about one data source. The sustainability team wants to shorten the disclosure by leaving out the framework name and the qualification because the conclusion is already “limited assurance”.

QWhat should the preparer do with the framework used and the qualification?
Reveal model answer →

Real reports

How 3 companies report it

Examples of full and partial reporting practice. These are evidence-led reviews, not exact disclosure templates to copy.

Real published reports

Cargill

Related

Food Production — Agricultural · United States · 2025 · p.77 ↗

Cargill’s 2025 Impact Report provides assurance specifically for Fiscal Year 2025 Scope 1 and Scope 2 market-based and location-based greenhouse gas (GHG) emissions, as stated on page 109. The assurance provider is identified as KPMG N.V., offering limited assurance on selected sustainability KPIs, though the report only partially details this on page 75. Notably, the report lacks a clear assurance opinion or conclusion, does not provide assurance status for Scope 3 emissions, and does not specify the assurance standard used, leaving these aspects unclear or missing.

Old Dominion Freight Line / ODFL

Related

Ground Transportation — Trucking · United States · 2024 · p.6 ↗

Old Dominion Freight Line’s 2024 Sustainability Report includes assurance on its scope 1 and 2 greenhouse gas emissions reporting, as noted on page 6, with reference to a 2024 GHG Inventory Verification Opinion mentioned on page 23. The report also references alignment with the GHG Protocol Corporate Standard on page 19, though the assurance standard is not clearly disclosed. Notably, the report does not provide information on assurance limitations, the assurance provider, assurance opinion or conclusion, or the status of scope 3 emissions assurance.

Host Hotels & Resorts, Inc.

Related

Real Estate · United States · 2025 · p.55 ↗

Host Hotels & Resorts, Inc.'s 2025 Corporate Responsibility Report includes verified data on Scope 1, Scope 2, and Scope 3 greenhouse gas emissions, with Scope 3 emissions specifically verified by AET, as noted on page 54. The report references assurance of its GHG emissions and environmental inventory data for the calendar year 2024, with related assurance statements found on pages 54-55 and 62. However, the report does not provide clear information on the assurance level, limitations, opinion, provider, or the specific assurance standard used, as these datapoints are either not found or unclear.
FieldCargillOld Dominion Freight Line / ODFLHost Hotels & Resorts, Inc.
Scope 1 and 2 coverageNot foundNot foundNot found
Assurance caveatsPartialNot foundNot found
Assurance conclusionNot foundNot foundNot found
Assurance providerPartialNot foundNot found
Scope 3 assurance statusNot foundNot foundNot found
Assurance method standardPartialPartialPartial

Full evidence map with quotes and page numbers →

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Framework references

Relevant California requirements and related disclosures

California

SB253-ASSURANCE

within California SB 253: Climate Corporate Data Accountability Act

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FAQ

Questions this page answers

SB253-ASSURANCE: what should I gather before I start the disclosure draft and how do I use the page’s step-by-step preparation section?+
SB253-ASSURANCE: which data points does this page say I need to prepare for the disclosure?+
SB253-ASSURANCE: how do I decide who owns the data for this disclosure across sustainability, HR, finance or operations?+
SB253-ASSURANCE: what evidence pack do I need to make this assurance-ready?+
SB253-ASSURANCE: what are the six assurance claims to verify and how should I use them?+
SB253-ASSURANCE: what common reporting gaps or mistakes does the page warn about?+
SB253-ASSURANCE: how do I use the Prep & Assurance workbook and printable Library Card?+
SB253-ASSURANCE: does the page include an example disclosure I can copy into my draft?+
SB253-ASSURANCE: how can I turn the page content into a draft disclosure and content-index line?+
SB253-ASSURANCE: can I reuse data from this page for ESRS E1 (Climate Change)?+

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