For years, sustainability reporting in the UK felt like a patchwork quilt, which is useful in parts, but rarely coherent. Companies reported greenhouse gas emissions through SECR, completed energy audits under ESOS, and then faced an alphabet soup of voluntary frameworks with little uniformity. The result? A system that generated data but rarely told investors what they actually needed to know.
That era is ending.
In 2025, the UK government launched a formal consultation on two landmark Sustainability Reporting Standards, SRS S1 and SRS S2, with the consultation window closing on September 17, 2025. These draft standards signal a clear direction: comprehensive, investor-grade sustainability disclosure is coming, and businesses that wait to prepare will pay the price.
No mandatory obligation exists yet, the standards are still in draft form. But the direction is unambiguous, and the window to prepare is open right now. Read on to find out exactly what SRS S1 and S2 require, who they apply to, and what your business should be doing today.
The UK Sustainability Reporting Standards are built on the foundation of the International Sustainability Standards Board (ISSB) frameworks — specifically IFRS S1 and IFRS S2 — but with deliberate modifications tailored to the UK market.
Think of them as two complementary lenses:
SRS S1 establishes a broad framework. It sets general requirements for disclosing sustainability-related financial information — any risk or opportunity that could reasonably affect a company’s cash flows, access to finance, or cost of capital over the short, medium, or long term.
SRS S2 zooms in on climate specifically. It requires companies to disclose how their governance structures handle climate-related risks and opportunities, how climate considerations shape strategy, and what their actual emissions numbers look like.
Together, they form a unified investor-focused disclosure system designed to put the UK in step with global capital markets.
This is the question every CFO and sustainability lead is asking right now.
The honest answer: the full scope isn’t finalized yet. The government’s consultation uses the phrase “economically significant entities” without defining it precisely. But reading between the lines, expect this to capture:
Right now, no UK company faces a mandatory obligation to report under SRS. The standards are still in draft form. Initially, reporting will be available on a voluntary basis, with mandatory requirements phased in once legislation is finalized.
But “voluntary for now” doesn’t mean “ignore for now.” Companies that build their reporting infrastructure early will be far better positioned — both for compliance and for competitive advantage.
SRS S1 structures sustainability disclosure around four core areas. If you’ve encountered the Task Force on Climate-related Financial Disclosures (TCFD) framework, these will feel familiar — because the underlying architecture is very similar.
What processes, controls, and procedures does your board and management use to monitor and oversee sustainability-related risks and opportunities? Who is accountable? How often does the board discuss these issues?
How does sustainability fit into your business strategy? What are the material risks and opportunities you’ve identified, and how do you plan to manage them over the short, medium, and long term?
How do you identify, assess, and prioritize sustainability-related risks? How does this process connect to your broader enterprise risk management?
What are you actually measuring? What targets have you set, or are you required to set by law? How are you tracking progress?
The critical word throughout SRS S1 is “material.” A sustainability-related risk or opportunity is material if omitting or misstating it could reasonably influence an investor’s decision. This financial materiality lens keeps the framework investor-focused and legally meaningful.
SRS S2 builds directly on the S1 framework but applies it specifically to climate. Under this standard, companies will likely need to disclose:
One important nuance: the UK version of S2 may allow companies to use classification schemes other than the Global Industry Classification Standard (GICS) for reporting financed emissions. This gives UK entities more flexibility than the original ISSB standard.
The UK government didn’t simply copy-paste the ISSB standards. The consultation proposes six meaningful modifications:
| Modification | What It Means |
| Comparative information | The UK may remove the transition relief that allows companies to delay comparatives in year one. This means you’ll need historical data from day one |
| Extended climate-first phase | Companies get up to two years to focus on climate reporting before expanding to all sustainability topics (versus one year under ISSB) |
| Classification flexibility | Companies can use classification schemes other than GICS for financed emissions |
| Effective date removed | Mandatory start dates will come through future legislation, not built into the standard itself |
| SASB references made optional | References to Sustainability Accounting Standards Board guidance will be permissive, not compulsory |
| Transition relief timing | Relief applies from either voluntary adoption or mandatory implementation — companies aren’t penalized for getting started early |
The extended two-year climate-first phase is particularly significant. It acknowledges that comprehensive sustainability reporting is genuinely complex, and gives companies breathing room to build capability before the full scope applies.
SRS doesn’t exist in isolation. UK businesses already navigate two established climate and energy reporting regimes:
ESOS (Energy Savings Opportunity Scheme) requires large organizations to conduct mandatory energy audits every four years. Phase 4 compliance is due by December 5, 2027. This is about measuring energy consumption and identifying savings, operational and internal in focus.
SECR (Streamlined Energy and Carbon Reporting) requires in-scope companies to report annual greenhouse gas emissions and energy consumption through their Companies House filings. This is public-facing and relatively straightforward in scope.
SRS is categorically different in ambition. Where ESOS and SECR focus on energy and emissions data, SRS asks a far broader question: What sustainability-related factors could affect your company’s financial performance, and how are you managing them?
SRS is an investor disclosure framework. It speaks the language of capital markets — risk, opportunity, materiality, strategy. That’s a fundamental shift from the operational compliance mindset of ESOS and SECR.
Here’s the perspective that separates leading companies from the rest: SRS isn’t just a reporting burden. It’s a prompt to do better business. Companies that genuinely embed SRS S1 and S2 into their operations (not just their annual reports) will gain several advantages:
The consultation period has closed, but final standards and mandatory timelines are still ahead. That gap is your runway. Here’s how to use it:
Preparing for SRS S1 and S2 isn’t just a legal exercise, it’s an operational transformation. And most businesses don’t have to figure it out alone. Clenergize offers end-to-end ESG services specifically designed to help organizations build the infrastructure that standards like SRS demand. Here’s where their expertise maps directly onto what SRS requires:
Whether your organization is taking its first steps toward SRS readiness or looking to close specific gaps, Clenergize brings the technical depth and strategic perspective to turn a compliance obligation into a genuine competitive advantage.
The UK’s Sustainability Reporting Standards represent the most significant shift in corporate disclosure requirements in a generation. SRS S1 and S2 move sustainability from the margins of annual reports to the very center — where investors, regulators, and stakeholders increasingly expect it to be.
The standards are still in draft. Mandatory timelines are still being set. But the direction is unambiguous, and the window to prepare is open right now.
Companies that treat SRS as a distant compliance problem will scramble when deadlines arrive. Companies that build their reporting infrastructure today, strong governance, reliable emissions data, clear strategy, and verified disclosures, will emerge with a credible, investor-ready sustainability story that sets them apart.
Clenergize helps businesses make exactly that transition. From sustainability reporting and ESG assurance to decarbonization strategy, sustainable finance advisory, and board-level ESG training, our end-to-end services cover every dimension that SRS S1 and S2 will demand.
The question isn’t whether to prepare for SRS. It’s whether you want to do it under pressure or on your own terms. Get in touch with Clenergize today and take the first step toward SRS readiness.
