UK sustainability reporting is proposed to move from voluntary to mandatory over three years.
Climate disclosures (UK SRS S2, excluding Scope 3) would start in January 2027 for the 515 listed companies in full scope,
with Scope 3 falling to comply-or-explain in 2028 and UK SRS S1 non-climate matters in 2029.
The UK SRS regulatory timeline, by actor
Four parallel tracks of activity from the UK Technical Advisory Committee's first recommendation to the proposed in-force date. Reading by row shows what each regulator did and when; reading by column shows the cluster of activity in early 2026.
Last verified 12 May 2026 · Footnotes link to primary sources
UK SRS by the numbers
Nine canonical figures that anchor the UK Sustainability Reporting Standards regime — every figure pinned to a primary source. The framing on this page sits behind every other reference page on the site.
Last verified 27 July 2026 · Updates as regulators publish new figures
UK SRS S1 (General Requirements) and UK SRS S2 (Climate-related Disclosures) released for voluntary use immediately, alongside the Government Response to the consultation.
DBT · UK SRS S1 and S2 publication
FCA analysis of the Official List as of January 2025: around 600 listed companies would be affected, of which 515 — across UKLR 6 (Commercial), 16 (Non-equity and non-voting equity) and 22 (Transition) — would be required to comply with the UK SRS proposals. Around 90 of the 515 are non-UK incorporated. UKLR 14 (Secondary) and 15 (Depositary Receipts) get a transparency and signposting statement only — no UK SRS reporting and no transition plan disclosure.
FCA · CP26/5 Annex 2 · paras 43, 45, 87
170 via online survey, 39 by direct email submission. 199 from organisations, 10 from individuals. 68% supported the four originally-proposed amendments.
Government Response · paras 1.6–1.7
Governance, Strategy, Risk Management, and Metrics and Targets. The structural foundation carried directly from TCFD (2017, disbanded 2023) — but disclosure requirements within each pillar are substantially enhanced.
UK SRS S2 · Paragraphs 5–37 · TCFD Recommendations
From purchased goods (Cat 1) to investments (Cat 15). Scope 3 is excluded from the proposed 1 January 2027 start; a company may elect a one-year transitional relief, and from periods beginning 1 January 2028 Scope 3 falls to comply-or-explain. The draft instrument sets no sunset on that comply-or-explain limb — Scope 3 does not become fully mandatory.
UK SRS S2 · Paragraphs B33–B58 · GHG Protocol Scope 3
Forty-plus jurisdictions covering approximately 60% of global market capitalisation, 60% of global GDP, and 40%+ of global greenhouse gas emissions. Latest additions: Ethiopia and Peru (Feb 2026).
IFRS Foundation · ISSB Update · April 2026
KPMG, PwC, Deloitte, and EY implementation studies converge on this range for a mid-cap listed company to build the data infrastructure, materiality assessment, quantitative scenario analysis, and disclosure drafting needed.
KPMG · CP26/5 implementation analysis
Four originally proposed plus additional final-version changes: paragraph B59A added, effective dates removed, ISSB December 2025 amendments incorporated.
Government Response · Chapters 1–2
The FRC's UK adaptation of the IAASB international sustainability assurance standard, issued 12 November 2025 for voluntary use — it governs how an assurance engagement is performed, not whether one must be obtained. FCA CP26/5 does not mandate assurance; it proposes a statement of whether assurance has been obtained.
FRC · ISSA (UK) 5000
Voluntary adoption (February 2026 onwards)
Any UK entity may adopt UK SRS from 25 February 2026.
Voluntary adopters must apply standards in full without transitional reliefs.
UK SRS S2 satisfies existing Companies Act climate disclosure requirements.
Phase 1 — UK SRS S2 proposed mandatory (1 January 2027)
Under the proposals in CP26/5 paragraph 3.4, UK SRS S2 climate disclosures — excluding Scope 3 — would become mandatory for accounting periods beginning on or after 1 January 2027 for in-scope listed companies.
The Cost Benefit Analysis states that "around 600 listed companies would be affected by our proposals", of which "515 listed companies with listings in either the commercial companies, non-equity shares and non-voting equity shares, or transition categories will be required to comply with our UK SRS proposals."
The 515 sit in the three full-scope categories — UKLR 6, UKLR 16 and UKLR 22 — and approximately 90 of them are incorporated outside the UK.
The balance of the roughly 600 affected are in the secondary listing (UKLR 14) and depositary receipts (UKLR 15) categories, which receive a transparency and signposting statement rather than a UK SRS reporting obligation.
First mandatory UK SRS S2 reports publish in spring 2028 for December 2027 year-ends.
Disclosure depth exceeds TCFD requirements with mandatory scenario analysis and connected information linking disclosures to the financial statements.
Non-calendar year-ends
Companies with periods beginning before 1 January 2027 may continue TCFD reporting or adopt UK SRS early.
Periods beginning on or after 1 January 2027 but before 1 January 2028 (paragraph 8.12).
The company must comply with the new UK SRS-aligned rules — or "explain" where permitted — unless it opts to make use of the transitional relief periods CP26/5 proposes, which are drawn from the pre-final exposure drafts; the final UK SRS S1 and S2 appendices themselves (¶E3, ¶C4) carry no time limit at all.
The Scope 3 one-year deferral and UK SRS S1 two-year deferral apply from the date of initial application, not from a fixed calendar date.
Periods beginning on or after 1 January 2028 but before 1 January 2029 (paragraph 8.14).
Same as the prior cohort, with the Scope 3 climate transitional relief no longer available (it expires after one year of initial application).
Excluded categories
Investment funds, shell companies, debt securities, and derivatives are excluded.
FCA may extend scope in future rule iterations.
Scope 3 comply-or-explain (January 2028)
How long UK SRS S2 implementation actually takes
Companies waiting for the FCA Policy Statement to begin preparation are already late. Practitioner consensus puts end-to-end implementation at twelve to eighteen months — driven by Scope 3 data, which can't be compressed.
Last verified 27 July 2026 · Click any workstream for detail
From kickoff to first UK SRS S2 report. Driven by Scope 3 supplier engagement and quantitative scenario modelling — neither compressible.
Of Scope 3 data work — from supplier engagement onset through validation. Of the 15 GHG Protocol categories, Category 1 and Category 11 typically account for >70% of total Scope 3 emissions.
Foundation phase before data work meaningfully begins. Materiality assessment and gap analysis are pre-requisites — running data collection without these creates wasted effort.
Scope 3 value chain emissions sit on a comply-or-explain footing throughout, and from accounting periods beginning on or after 1 January 2028 the elective one-year transitional relief is no longer available to suspend it.
A company must then either disclose Scope 3 in accordance with UK SRS S2 or identify the paragraphs it has not applied, the reasons, and the steps it is taking to disclose in future.
The draft instrument carries no sunset on that comply-or-explain limb, so nothing becomes fully mandatory in 2028.
See Scope 3 under UK SRS for category details.
UK SRS S2 incorporates December 2025 ISSB reliefs for financed emissions methodology flexibility
and jurisdictional measurement alternatives.
Broader sustainability comply-or-explain (January 2029)
The elective two-year relief for UK SRS S1 non-climate topics (biodiversity, water, workforce, supply chain)
expires for accounting periods beginning on or after 1 January 2029, leaving those topics on a permanent comply-or-explain footing.
S1 conceptual foundations apply from 2027 alongside S2.
Modernising Corporate Reporting: the second wave
CP26/5 only covers listed issuers.
The DBT consultation response (paragraph 1.16) states that the MCR programme "will include consideration of the need for requirements within the Companies Act for private entities to report against UK SRS" — consideration, not commitment.
The MCR consultation had not been published as at 22 August 2026; the latest stated timing is "later in 2026", with no firm date.
The MCR programme has two distinct strands.
Strand one — reporting reductions for medium-sized private companies.
Set out in the Written Ministerial Statement of 21 October 2025, this strand introduces three legislative changes:
- Most medium-sized private companies exempted from the Strategic Report requirement
- Wholly-owned subsidiaries exempted from the Strategic Report where they are covered by a UK parent's group report
- The Directors' Report requirement removed for all companies, with useful provisions (including SECR-style energy and emissions reporting) relocated elsewhere
The Government estimates these reforms will benefit up to 44,000 medium-sized private companies and 7,000 subsidiary companies, and remove the Directors' Report requirement from approximately 440,000 companies — saving UK businesses around £230 million per year in administrative costs.
Strand two — whether to extend UK SRS to economically significant private companies.
The DBT consultation response paragraph 1.16 confirms the question will be considered within the broader MCR consultation.
Three issues that consultation would have to resolve:
- Defining "economically significant." Paragraph 1.61 of the DBT response records that respondents asked for a clear definition. No definition has been published, and no government or regulator document proposes a threshold. Figures circulating in commentary are speculation, and the estimates in circulation differ from one another by an order of magnitude.
- Subsidiary exemptions. Paragraph 1.67 records strong respondent support for an exemption where a parent company already reports against UK SRS or an equivalent international standard (such as ESRS).
- Phasing and proportionality. Paragraph 1.68 records that "proportionality is the priority for consultation respondents" and that a phased approach with a longer preparation period is expected.
For practical planning purposes: no commencement date exists to plan to, because the consultation that would set one has not been published.
See UK SRS for private companies for the detailed cohort analysis.
Assurance: ISSA (UK) 5000 effective from 15 December 2026
UK SRS does not mandate third-party assurance.
CP26/5 proposes a disclosure obligation on whether assurance has been obtained, the level (limited or reasonable), the standards used, and the identity of the assurance provider — but not a requirement to obtain assurance.
The FRC's parallel work has produced the UK version of the International Standard on Sustainability Assurance — ISSA (UK) 5000, published on 12 November 2025.
Key facts:
- Effective: for periods beginning on or after 15 December 2026
- Voluntary use only — not mandated by either the FRC or the FCA
- Profession-agnostic — applies to professional accountants and other practitioners who meet the relevant quality management and ethical requirements
- Both limited and reasonable assurance supported
- Aligned with the international IAASB standard — only one UK-specific modification, a safeguard preventing internal auditors from directly assisting in sustainability assurance engagements
- Consultation history: opened 29 May 2025, closed 31 July 2025; feedback paper and final standard both published 12 November 2025
The combination of ISSA (UK) 5000 effective December 2026, UK SRS S2 proposed mandatory January 2027, and CP26/5's voluntary-assurance disclosure obligation means the assurance market is taking shape now.
In-scope listed companies should expect investor and audit committee questions on whether they intend to obtain voluntary assurance from 2027 onwards.
Full chronological timeline
What to do this year
Three things in-scope listed companies should be doing in 2026:
**1.
Run a gap analysis against UK SRS S2.**
Most TCFD-aligned reporters will find that the governance pillar (Pillar 1) and risk management pillar (Pillar 3) carry over with limited change.
The step changes are concentrated in three areas: the quantitative climate scenario analysis required by paragraph 22 (see climate scenario analysis under UK SRS); the connected-information requirements linking disclosures to the financial statements, required throughout the standard; and the cross-industry climate metrics in Appendix B, which include items most TCFD-aligned reports have not previously quantified.
**2.
Start the Scope 3 data conversation early.**
Even where the elective one-year Scope 3 relief is taken, value-chain emissions data takes 12-18 months to collect and validate to audit-grade.
Identify which Scope 3 categories are material now; engage the largest 20-30 value chain partners; pilot a calculation method.
The December 2025 ISSB amendments allow some financial-sector entities to limit Scope 3 Category 15 to financed emissions, which simplifies the position for banks, insurers and asset managers — but only if the financed-emissions methodology is itself ready.
**3.
Decide on assurance.**
UK SRS does not mandate third-party assurance, but CP26/5 proposes a disclosure on whether assurance has been obtained.
With ISSA (UK) 5000 effective from 15 December 2026, the voluntary-assurance market is forming.
Audit committees should expect investor questions on assurance intent from the 2027 reporting cycle onwards.
For listed companies in UKLR 14 (secondary listing) and UKLR 15 (depositary receipts), the work is different: identify the climate and sustainability reporting standards applicable in the primary listing jurisdiction, confirm any reliefs claimed under those standards, and identify any voluntarily adopted standards.
The FCA's transparency-focused regime requires disclosure of what already applies, not new UK reporting.
Frequently asked questions
Is UK SRS S2 proposed mandatory yet?
Not yet.
UK SRS S2 was published on 25 February 2026 and is available for voluntary adoption.
The FCA's CP26/5 consultation, which closed on 20 March 2026, proposes making it mandatory for in-scope listed companies for accounting periods beginning on or after 1 January 2027.
The final FCA Policy Statement is expected in autumn 2026.
How many companies are in scope?
The FCA's Cost Benefit Analysis puts 515 listed companies in full scope and around 600 affected in total.
Annex 2 paragraph 43 states that "around 600 listed companies would be affected by our proposals" and that, of these, 515 with listings in the commercial companies, non-equity shares and non-voting equity shares, or transition categories "will be required to comply with our UK SRS proposals".
Paragraph 45 records that approximately 90 of the 515 are incorporated outside the UK.
The remainder of the 600 are in the secondary listing (UKLR 14) and depositary receipts (UKLR 15) categories, which are subject to a transparency and signposting statement rather than UK SRS reporting.
Which UKLR categories are not in scope?
Six categories are excluded: closed-ended investment funds (UKLR 11), open-ended investment companies (UKLR 12), shell companies (UKLR 13), debt and debt-like securities (UKLR 17), securitised derivatives (UKLR 18), and warrants, options and miscellaneous securities (UKLR 19).
For UKLR 11 and 12, the FCA's view is that reporting should fall on the asset manager rather than the fund; for the others, the FCA considers that direct reporting would not be proportionate or effective at this stage.
What about non-calendar year-ends?
CP26/5 paragraph 8.10 addresses listed companies whose accounting period begins before 1 January 2027 — they may either continue with TCFD-aligned rules for that period or voluntarily apply UK SRS early.
For periods beginning on or after 1 January 2027 but before 1 January 2028 (paragraph 8.12), the new UK SRS-aligned rules apply, with transitional reliefs available under the standards themselves.
The Scope 3 one-year deferral runs from the date of initial application, not from a fixed calendar date.
Will UK SRS replace TCFD reporting?
For in-scope listed companies, yes, once CP26/5 rules take effect from 1 January 2027.
UK SRS S2 incorporates the four TCFD pillars and goes further on quantitative climate scenario analysis, connected information linking disclosures to the financial statements, and cross-industry metrics.
The TCFD itself was disbanded on 12 October 2023, with monitoring of climate-related disclosure adoption transferred from the TCFD in 2024 — the FSB's own request names the ISSB, while the IFRS Foundation's release uses both the IFRS Foundation and the ISSB in the same document.
SECR (energy and emissions reporting under the Companies Act) is a separate regime that continues; DESNZ published its statutory post-implementation review of SECR on 26 May 2026 recommending that SECR be retained with amendments rather than removed, with refinements to be explored through a planned 2026 consultation on streamlining energy and emissions reporting that had not launched as at 22 August 2026.
What is the Scope 3 transitional relief and when does it expire?
It is elective, not automatic.
CP26/5 paragraph 8.6 proposes that an in-scope company may opt not to disclose Scope 3 greenhouse gas emissions in its first year of mandatory UK SRS S2 reporting; electing the relief requires only a statement in the annual financial report that the disclosures have not been made, and the FCA confirms that "use of the UK SRS transitional reliefs does not engage our proposed 'explain' provisions".
Companies already disclosing Scope 3 may carry on doing so.
For accounting periods beginning on or after 1 January 2028 the relief is no longer available and Scope 3 sits on a comply-or-explain basis, which the draft instrument leaves in place with no sunset — so Scope 3 does not become fully mandatory in 2028 or at any later announced date.
The December 2025 ISSB amendments permit financial-sector entities to limit Scope 3 Category 15 to financed emissions as defined in UK SRS S2 — a meaningful simplification for banks, insurers and asset managers.
When does UK SRS S1 become mandatory?
UK SRS S1 non-climate disclosures sit on a comply-or-explain basis, with an elective two-year transitional relief available for periods beginning on or after 1 January 2027 and 1 January 2028.
From periods beginning on or after 1 January 2029 all the CP26/5 transitional reliefs have expired, and S1 non-climate disclosures apply on that comply-or-explain basis without a sunset.
The S1 conceptual foundations — definitions of materiality, scope of the value chain, "Connected information" (¶¶21–24), safe-harbour provisions — apply from January 2027 alongside UK SRS S2, because S2 cannot be applied without them.
What about private companies?
CP26/5 only covers listed issuers.
The Government has committed to consider whether to extend UK SRS to economically significant private companies through the Companies Act 2006, within the broader Modernising Corporate Reporting programme.
That consultation had not been published as at 22 August 2026.
No threshold and no commencement date has been proposed by any government or regulator document, and figures circulating in commentary are speculation.
Is sustainability assurance mandatory under UK SRS?
No. CP26/5 proposes only a disclosure obligation on whether assurance has been obtained, the level, the standards used, and the provider.
The FRC published ISSA (UK) 5000 — the UK sustainability assurance standard — on 12 November 2025, effective for periods beginning on or after 15 December 2026, but its use is voluntary.