BigCat Research

SROI vs sustainability reporting (ISSB, GRI)

Short answer: A sustainability report under TSRS/ISSB or GRI tells readers how sustainability matters affect the company, or how the company affects the economy, environment and people, across the whole organisation. An SROI or impact study asks a narrower question: what changed for the people one programme reached, and what that change is worth. If you already report under TSRS or GRI and need to show what a specific programme achieved, you still need programme-level measurement. The report was not built to produce that evidence.

Disclosure: BigCat Research sells social impact analysis and SROI measurement services. We do not provide TSRS assurance or legal compliance advice. Every factual claim below links to a source we opened.

Why the question comes up

Picture a typical case (illustrative, not a client): the sustainability team at a listed company has spent months on its first TSRS report. Then the CSR team asks for a budget to measure a scholarship programme for vocational students, and a board member might reasonably ask: "Don't we already report on this?"

Mostly, no. The two documents share vocabulary such as "material", "stakeholders" and "impact", but they use those words for different readers. The SROI guide itself acknowledges the overlap: it says SROI shares basic principles, such as engaging with stakeholders, with the Global Reporting Initiative and AccountAbility's AA1000 standards.¹ It then names the difference. SROI builds simple theories of change for the significant changes stakeholders experience and puts financial proxies on the value of those impacts.¹

Three frameworks, three questions

TSRS 1 / IFRS S1 is investor-facing. The IFRS Foundation states the objective of IFRS S1 as requiring an entity to disclose information about its sustainability-related risks and opportunities that is useful to users of general purpose financial reports when they decide whether to provide resources to the entity.² In Türkiye, the Public Oversight Authority (KGK) put the Turkish Sustainability Reporting Standards into force by Board Decision 21632, published in the Official Gazette on 29 December 2023, for reporting periods beginning on or after 1 January 2024.³ The IFRS Foundation's profile of Türkiye says TSRS 1 is IFRS S1 adopted locally, and that the information is aimed at existing and potential investors, lenders and other creditors.⁴

So the TSRS question is, roughly: "How could sustainability issues change this company's financial prospects?"

The GRI Standards look the other way. GRI says its Standards let any organisation understand and report on its impacts on the economy, environment and people.⁵ The revised Universal Standards were published in October 2021 and came into effect for reporting on 1 January 2023.⁵ The GRI question is closer to: "What does this organisation do to the world around it?"

SROI works at a smaller scale. The SROI guide, now hosted by the Institute for Social Value (formerly Social Value UK), describes it as a framework for measuring and accounting for a broader concept of value than financial return alone, measured in ways that are relevant to the people who experience or contribute to the change.¹ It can cover an entire organisation or one specific part of its work.¹ It uses money values for outcomes, so a ratio of benefits to costs can be calculated; a ratio of 3:1 means £1 invested delivers £3 of social value.¹ Its question is: "What changed for these people because of this activity, and is it worth what it cost?"

Think of a bakery. Its accounts show the bank whether the business is sound. A customer survey tells the owner what regulars think of the bread. Neither tells you whether the free baking course the bakery runs for unemployed neighbours actually got anyone a job.

Side-by-side comparison

Three caveats on the table. First, where the GRI column says "not covered", we only opened GRI's overview page and did not check the full Standards. Second, we deliberately left out TSRS thresholds and scope; they are set by KGK decisions and can change, so check the current text with your legal or compliance adviser. Third, SROI's version of materiality is borrowed from accounting, as the guide itself says: information is material if it could affect readers' or stakeholders' decisions, or if leaving it out would misrepresent the activities.¹ TSRS ties materiality to investors' decisions about the entity's finances.⁴

What a sustainability report cannot tell you about a programme

Suppose the company's TSRS report says the scholarship programme reached 400 students. (That figure is illustrative.) An investor reading the report learns that the programme exists and perhaps what it cost. They do not learn whether the students finished school at a higher rate than similar students without scholarships, how the families valued the change, or whether some of those students would have finished anyway.

Unless a scholarship programme could reasonably be expected to affect the company's cash flows, access to finance or cost of capital, TSRS does not require it to be disclosed, so it may not appear in the report at all.⁴ GRI comes closer, because it asks about impacts on people.⁵ But a GRI report covers the organisation as a whole. It is not, by its nature, a study that tests whether one programme caused a change.

SROI, by contrast, starts with the people affected. The first Principle of Social Value is to involve stakeholders in deciding what gets measured and how it is measured and valued.⁶ Another is "Do not overclaim": only claim the value the activities are responsible for creating.⁶

What SROI cannot do for you

SROI is no substitute for disclosure. It does not satisfy TSRS. The guide also warns that comparing social return ratios alone between organisations is not appropriate, because each analysis rests on different stakeholders and judgements.¹ So an SROI ratio is a poor fit for the comparable, entity-wide figures investors expect.

It is also built on judgement. The guide says there is "no substitute for the practitioner's judgement" and asks that materiality decisions be documented.¹ That is fine for a programme decision. It is a weakness if someone tries to use one ratio as a headline in an annual report.

How they fit together

Neither replaces the other; each can feed the other.

• Use the sustainability report for what regulators and investors require, and for the organisation-wide picture of impacts.
• Use programme-level measurement when you need to decide whether to keep or change a specific programme, or when a funder asks what changed.
• Carry the findings across. Results from an impact study can be summarised in the sustainability report as supporting evidence. TSRS allows additional disclosures alongside the required ones, as long as the TSRS information stays clearly identifiable and is not obscured by them.⁴

Our social impact analysis work collects that programme evidence through surveys and interviews with the people a programme reached. If you are drafting a tender for such a study, the guide to commissioning a social impact assessment or SROI lists what the brief should contain. For turning the results into language a sustainability or communications team can use, see how to simplify the impact narrative for corporate communication, sustainability and stakeholder management. If the output is a CSR report, our CSR report preparation service covers that format, and the BIG 101 note on which evidence a CSR report should include sets out the basics.

Want a rough sense of scale first? Our free SROI calculator shows how deadweight, attribution and drop-off change an illustrative ratio. Treat its output as a sketch for a planning conversation, not a figure to publish.

FAQ

1. We already publish a GRI report. Do we still need an SROI? Only if someone needs to know what a specific programme changed and what that change is worth. GRI reports cover an organisation's impacts on the economy, environment and people.⁵ SROI measures the value one activity creates for the people who experience it, using financial proxies.¹ If no decision depends on that programme-level answer, an SROI may not be worth the effort.

2. Can an SROI ratio go into our TSRS-compliant sustainability report? TSRS permits additional disclosures alongside the required ones, provided the TSRS information remains clearly identifiable and is not obscured.⁴ Whether a particular figure belongs there is a question for your reporting and assurance advisers. If you include a ratio, show the assumptions with it, since the SROI guide says ratios alone should not be compared between organisations, because each rests on different stakeholders and judgements.¹

3. Is "material" the same thing in SROI and in TSRS? No. In TSRS, material information is what could reasonably be expected to affect the company's cash flows, access to finance or cost of capital.⁴ In SROI, information is material if leaving it out would misrepresent the activities or could affect stakeholders' decisions.¹ The same programme can be material in one sense and not the other.

4. Who checks an SROI report? Social Value International offers report assurance, an independent review of whether an SROI or social impact report follows the Principles of Social Value.⁷ It is separate from the assurance of sustainability disclosures, which in Türkiye was set at limited assurance from the first reporting year, according to the June 2025 IFRS Foundation profile.⁴

5. Is SROI required by law in Türkiye? None of the sources we opened makes SROI a legal requirement. TSRS, by contrast, was put into force by a KGK Board Decision for reporting periods starting on or after 1 January 2024.³ Which entities must report under TSRS is set by KGK decisions; confirm the current scope with a compliance adviser.

Sources

Author: BigCat Research team. Last reviewed: 15 October 2026.