515. That is the FCA’s own estimate of how many UK-listed companies will be required to report against the UK Sustainability Reporting Standards (UK SRS) from January 2027, under its current proposals. For context, the FCA’s review covered around 600 issuers across the categories in scope. Of the circa 1,500 companies listed on the London Stock Exchange altogether, a large share sits on AIM, which falls outside these proposals entirely. Strip those out, and 515 represents a substantial share of everything left on the Main Market.

It’s easy to assume that it’ll mostly hit large-cap names with FTSE 100 -level resource behind them. But the FCA’s proposed scope isn’t based on size, turnover or headcount, it’s based on listing category. If your securities sit in UKLR 6 (Commercial Companies), UKLR 16 (Non-Equity Shares) or UKLR 22 (the Transition Category), you’re in scope regardless of your market cap. A number of the companies in that 515 are exactly the kind of mid- and small-cap businesses we work with every day, and some may be hoping they fall outside the final scope when the FCA publishes its rules, expected this autumn. Sadly, that’s unlikely.

Less of an overhaul, but not “just disclosure”

With any regulatory change, it’s natural to worry about what it will look like in practice. The good news is that the current proposals are clear, and you don’t need to start from scratch. UK SRS was published in final form by the Department for Business and Trade on 25 February 2026. If you’ve already done TCFD reporting, that gives you a genuine headstart. But this isn’t simply disclosing what you already know in a different format, there is real work involved. UK SRS is built on financial materiality. It doesn’t ask you to report on everything sustainability-related under the sun, only on what’s genuinely material to your prospects. That’s a narrower, more commercial lens than many companies expect or may be used to, but it will still demand new processes, governance, disclosures and understanding from many in-house teams.

What preparation actually looks like

Financial materiality is the starting point, but it doesn’t cover everything. A strong UK SRS position isn’t just about knowing what’s material to your company, it’s about being able to explain, with evidence, why. That will require:

• Governance that can stand behind – and answer for – your data and disclosures. Boards need to be able to demonstrate oversight, knowledge and expertise of sustainability-related risks and opportunities and how they are part of the risk management framework, not just sign off a report someone else prepared. That’s a shift in what Board discussions need to cover and puts pressure on Boards to upskill to meet this challenge.
• Data that traces back and can be verified. Forecasts and estimates need a defensible method and data trail behind them, consistently applied and reviewed if circumstances change. Even if investors don’t always ask the in-depth questions, your auditors certainly will.
• Finance and sustainability teams need to be talking well before the year-end. UK SRS pushes your sustainability considerations into financial statements. That only works if the teams producing each are talking to each other well before year-end and not reconciling positions as part of the annual report process.
• A clear and cohesive narrative. Regulators and investors will expect a coherent line from financial materiality assessment through to strategy and financial planning. It can’t be three different approaches that don’t quite agree with each other. This also means that sustainability needs to be fully embedded and can’t be run in silo – a theme you will have heard us discuss consistently over the years.

It is also worth being clear that, no matter how the wider scope of UK SRS develops in the future, you will not be able to escape climate. UK SRS S2 is what the FCA is proposing to mandate outright, while the broader S1 disclosures get a comply-or-explain grace period. In practice, that means getting comfortable with your emissions data, transition planning, physical risk and climate-related financial exposure sooner rather than later.

None of this can happen all at once. Nor does it need a large in-house function to get moving. However, it does need to start now, because governance practices, knowledge transfer, data processes and cross-team working relationships take time to embed, and none of them are the kind of thing you can build in the weeks before a deadline.

Assurance is coming too

Alongside all this, that scrutiny we often speak of is about to get a formal rulebook. Assurance, independent checking of your sustainability disclosures, is also arriving this year via a separate standard, ISSA (UK) 5000, published by the Financial Reporting Council in November 2025 and effective from 15 December 2026. We don’t think UK SRS itself will require mandatory assurance in its early years, but the standard is already shaping what “good” looks like for companies choosing to be assured voluntarily, and that bar has a way of becoming the reference point for everyone, not just early adopters. Add it to UK SRS itself, and the direction is clear. Boards and in-house teams will be under growing pressure to get governance, data and reporting right the first time, rather than having to tidy it up under scrutiny later.

Why waiting is the expensive option

So, going back to where we started. If you’re one of the 515, or think you might be, “wait and see” isn’t a strategy. It is a gamble that the FCA’s autumn Policy Statement will let you off the hook. Companies that leave this until the rules take effect will be building governance, data and Board understanding under pressure, with the clock already ticking. Starting now, while UK SRS is still voluntary, is how you buy back time you won’t get once it lands. We are already seeing some of the bigger FTSE 100 names adjust their disclosures to align with UK SRS. Most others will have to follow suit.

SIFA Strategy helps management teams identify, implement, and embed ESG priorities to drive company value and resilience, including preparing for UK SRS and the sustainability assurance regime building around it. If you’d like to talk through where your organisation stands, please do not hesitate to get in contact.