If you're reading this, someone has probably told you your company needs to publish a sustainability report — and the brief either came with no further context, or with so much context that you don't know what to do with it. Either way, the same questions tend to come up first: What is this, exactly? Why is my company being asked to do it? And where do we start?
This guide answers those questions in plain language. By the end you'll know what a sustainability report is, who reads it, what frameworks govern it, and how to think about getting started — even if your company has never published one before.
What sustainability reporting actually is
A sustainability report is a public disclosure of how a company affects — and is affected by — environmental, social, and governance issues. That covers things like greenhouse gas emissions, energy and water use, workforce data, supply chain practices, human rights, and how the business is governed. The output is usually an annual document, structured against one or more standardized frameworks, that's read by investors, banks, regulators, large customers, and other stakeholders.
The structured part is the important bit. Sustainability reporting isn't just "a paragraph about our environmental commitments" in your annual report. It's a disciplined disclosure exercise where you measure specific things, calculate them in specific ways, and present them in a specific structure — so that anyone reading your report can compare you against another company doing the same exercise. The frameworks (GRI, IFRS S1 and S2, the GHG Protocol, and others) are what makes the comparison possible.
Why companies do sustainability reporting
Sustainability reporting started as a voluntary practice in the 1990s, mostly by large multinationals trying to communicate environmental and social commitments to stakeholders. For most of its history, it was a discretionary activity — we report because we want to, not because we have to.
That's changing fast. Sustainability reporting is becoming mandatory in a growing number of jurisdictions, and the requirements are getting more specific each year. The reasons are worth understanding because they shape what your reporting actually has to do.
Investor demand
Climate and social risks have become material to financial performance. Investors and lenders increasingly need consistent, comparable data on how companies are managing those risks before they make capital allocation decisions. The IFRS Foundation issued IFRS S1 and S2 in June 2023 specifically to give investors a global baseline of sustainability information they can compare across markets. These standards are effective for annual reporting periods beginning on or after 1 January 2024, and a growing list of jurisdictions — Australia, the UK, Hong Kong, Singapore, Brazil, and others — are adopting them as mandatory.
Regulatory mandates
The European Union's Corporate Sustainability Reporting Directive (CSRD) requires roughly 42,500 EU and EU-connected companies to disclose against the European Sustainability Reporting Standards (ESRS). California's SB 253 requires large companies "doing business in California" with annual revenues over USD 1 billion to disclose Scope 1 and Scope 2 emissions starting in 2026, and Scope 3 starting in 2027. The UK is finalizing its UK Sustainability Reporting Standards. India's BRSR regime applies to top-listed entities. Most major economies have a mandatory or emerging mandatory sustainability disclosure regime in place or under development.
Stakeholder and customer pressure
Even companies outside the scope of any specific mandate are being asked for sustainability data — often by their largest customers, who need that data to complete their mandatory reports. If you supply or do business with a company in scope of CSRD, IFRS S2, or California's climate rules, you're probably already receiving questionnaires asking for sustainability data. Banks increasingly factor ESG performance into lending decisions. Procurement processes at large enterprises and governments often require sustainability disclosures from suppliers.
Internal use
A meaningful share of companies report not because anyone is asking, but because the discipline of measurement creates better operational decisions. You can't manage what you don't measure, and a sustainability report is essentially a structured measurement exercise.
The reasons differ by company, but the trajectory is consistent: sustainability reporting is moving from optional to expected, and from expected to required.
What goes in a sustainability report
The exact contents depend on which framework you're reporting against, but most sustainability reports cover roughly the same territory.
Strategy and governance
Who runs sustainability at your company. How the board oversees sustainability risks and opportunities. Your sustainability strategy, targets, and how you incorporate sustainability into your business model.
Material topics
The sustainability issues that matter most to your business and stakeholders, and how you identified them. Most frameworks require a materiality assessment — a structured process for figuring out which topics deserve detailed disclosure.
Environmental performance
Greenhouse gas emissions (typically broken down into Scope 1, Scope 2, and Scope 3 — direct emissions, energy emissions, and value-chain emissions). Energy consumption. Water use. Waste generation. Air quality. Biodiversity impacts. Increasingly, climate-related risks and opportunities under frameworks like IFRS S2.
Social performance
Workforce data — headcount, diversity, training, health and safety. Human rights due diligence. Community engagement. Supply chain labor practices. Product safety and customer privacy.
Governance and ethics
Board composition. Executive compensation linked to sustainability. Anti-corruption programs. Whistleblower mechanisms. Tax transparency.
Methodology and assumptions
What boundaries you set, what calculations you used, what data sources you relied on, and where your numbers came from. This is the part that makes the report auditable — and it's often the most overlooked part by first-time reporters.
A typical mid-sized company's first sustainability report ends up somewhere around 80 to 150 individual disclosure data points across these areas, depending on which framework you're using and which topics turn out to be material.
The frameworks you'll encounter
Three frameworks dominate global sustainability reporting practice. They do different jobs and are increasingly designed to work together rather than compete.
GHG Protocol
The measurement engine. It tells you how to calculate your greenhouse gas emissions — what to count, how to count it, and how to organize it into Scope 1 (direct emissions you own), Scope 2 (electricity, steam, heat, or cooling you buy), and Scope 3 (everything else in your value chain). Almost every other climate disclosure framework references GHG Protocol as the underlying measurement standard. Issued by the World Resources Institute and the World Business Council for Sustainable Development.
GRI (Global Reporting Initiative) Standards
The broadest reporting framework. They tell you what to disclose to a wide audience — investors, employees, communities, regulators, customers — about your company's impacts on the economy, environment, and people. GRI is voluntary, but it's the most widely used sustainability reporting framework in the world, and is referenced or required by regulators, stock exchanges, and procurement processes in over 100 countries. GRI was significantly revised in 2021, with the current Universal Standards (GRI 1, 2, and 3) effective for reports published on or after 1 January 2023.
IFRS S1 and S2
Investor-focused disclosure standards from the International Sustainability Standards Board (ISSB), part of the same IFRS Foundation that issues the IFRS Accounting Standards. S1 covers general sustainability-related disclosures; S2 covers climate specifically. Both are designed to provide a global baseline that jurisdictions can adopt or build on. They incorporate the recommendations of the Task Force on Climate-related Financial Disclosures (TCFD), and from 2024 the ISSB has formally taken over TCFD's monitoring role.
In practice, most companies use GHG Protocol to measure emissions, then report those emissions through GRI (for stakeholder communication) and/or IFRS S1/S2 (for investor communication). They're complementary, not competing — and beyond these three core frameworks, you'll likely also encounter SBTi (for science-based emissions targets), CDP (for climate questionnaires), TNFD (for nature-related disclosures), and a growing list of region-specific regimes.
If choosing the right framework feels confusing right now, that's normal — and not something you have to solve in your first week.
Who reads a sustainability report
Different frameworks are designed for different audiences, but in practice most sustainability reports are read by some combination of:
- Investors and lenders — assessing climate, transition, and operational risks before making capital decisions
- Banks — increasingly factoring ESG performance into lending
- Customers — particularly large ones who need supplier data for their own reporting
- Regulators — checking compliance with mandatory disclosure regimes
- Employees and prospective employees — assessing the company's culture, values, and stability
- Communities and NGOs — monitoring impacts on local environments and people
- Procurement and tender processes — using ESG performance as a qualifying criterion
- Auditors — verifying that what you report is accurate and well-supported
The audience matters because it shapes what your report needs to do. If your investors are the priority, IFRS S1/S2's enterprise-value focus is the right register. If your customers and broader stakeholders are the priority, GRI's impact-focused approach fits better. Most companies eventually report against both because their audiences include both.
Mandatory vs voluntary: where you might fit
A common first question is "do we actually have to do this?" The honest answer depends on three things: where you operate, your size, and who's asking.
You probably have to report if any of these apply
- You're a listed company in the EU, UK, Australia, New Zealand, Hong Kong, Singapore, Japan, Brazil, India, or a growing list of other jurisdictions
- You're a large EU undertaking under CSRD's phased thresholds
- You do business in California with annual revenues above the SB 253 threshold (approximately USD 1 billion)
- You're a financial institution in a jurisdiction that has adopted IFRS S2 or its local equivalent
- You're already in scope of a sector-specific or country-specific reporting regime
You probably should report — even if not legally required — if any of these apply
- Your major customers are asking you for sustainability data
- You're applying for ESG-linked financing or sustainability-linked loans
- You're in the supply chain of a company in scope of CSRD or another mandatory regime
- You're preparing for a future IPO, acquisition, or significant capital raise
- You're being asked to complete CDP, EcoVadis, or other sustainability questionnaires
You probably don't have to report — but might benefit from voluntary disclosure — if you're a smaller private company without the above pressures, but want to use the discipline to build operational visibility, attract talent, or pre-empt future regulation. The EFRAG Voluntary SME Standard (VSME) was designed specifically for this case.
The trajectory is consistent regardless: sustainability reporting is moving from optional to expected to required. Even companies that aren't required to report today will likely be required to within the next 3 to 5 years.
How long a first sustainability report typically takes
This is the question every first-time reporter asks, and the honest answer is longer than you think for the first one, and much faster after that. The frameworks themselves don't prescribe timelines, but practical experience suggests:
A first GRI- or IFRS-aligned report
Typically a multi-month project — often four to six months of intensive work, sometimes longer. Most of that time goes into things you only do once: setting up your data model, identifying material topics, mapping data sources across departments, choosing emission factors, and building the calculation infrastructure.
A first GHG inventory
Scope 1, 2, and 3 typically takes three to six months of dedicated work, with most of the time spent on Scope 3 — the value-chain emissions that require gathering data from suppliers, customers, and other external parties.
Subsequent reports
Dramatically faster. By year three, most companies are publishing in weeks rather than months — because the data infrastructure exists, the methodology is established, and the team knows what they're doing.
Key takeaway
The first year is the slow year. Plan accordingly, and don't beat yourself up if it feels harder than it should.
Where first-time reporters typically go wrong
If you're reading this, you're already ahead of the curve simply by trying to learn the basics. But there are a handful of mistakes that catch almost every first-time reporter, and they're worth knowing about now so you can avoid them.
Treating it as a checklist instead of starting from materiality
The temptation is to look at a framework's full list of disclosures and try to answer every single one. That produces bloated reports that aren't useful to anyone. The right starting point is a structured materiality assessment that identifies which topics actually matter for your business — and then selecting the disclosures that cover those topics.
Making vague claims you can't back up
"We're committed to net zero" without a base year, target year, or methodology is the kind of statement regulators and stakeholders are increasingly challenging. The EU's Green Claims Directive, the FTC's Green Guides, and similar rules globally are tightening what companies can claim publicly. If you can't back up a sustainability claim with specific data, methodology, and evidence, don't make it.
Inconsistent boundaries year-over-year
Once you set your reporting boundary (which entities and operations you're including), you need to stick with it. Changing from operational control to financial control between years, or excluding a major joint venture without explanation, undermines the credibility of every comparison you make.
Reporting only Scope 1 and 2 emissions and ignoring Scope 3
Scope 3 is the hardest to measure, but it's typically more than 70% of total emissions for most companies. CSRD, IFRS S2, California SB 253, SBTi, and most other significant regimes are moving toward mandatory Scope 3 reporting. A credible sustainability report has to engage with Scope 3 — even if your first attempt is a screening exercise that flags categories for future improvement.
Cherry-picking the metrics that look good
Reporting only the disclosures where the company performs well, while quietly omitting unfavorable ones, is the fastest way to lose credibility with sophisticated readers — and the kind of issue that gets flagged in assurance engagements.
Not building an audit trail
Even if your first report isn't externally assured, the discipline of documenting where every number came from, what calculations you used, and what assumptions you made is what separates a credible sustainability report from a marketing exercise. Auditors working under ISAE 3000, ISAE 3410, and the new ISSA 5000 standards expect this kind of documentation. Your future self will thank you for building it from day one.
How to start
If you've gotten this far and you're thinking okay, but what do I actually do on Monday morning? — here's a sensible starting sequence.
Get clarity on who's asking and what they're asking for
Before you choose a framework, write down who the audience for your report is. Investors? A specific customer? A regulator? Multiple stakeholders? The answer shapes which framework(s) make sense to start with.
Pick a framework
If your investors are the priority and you're in or moving toward an IFRS-adopting jurisdiction, start with IFRS S1/S2. If your stakeholders are broader (employees, communities, customers, NGOs), start with GRI. If you're starting with emissions specifically, GHG Protocol is the underlying methodology either way. Most companies eventually use a combination, but you don't need to start with all of them on day one.
Identify the people involved
Sustainability reporting almost always crosses departments — finance, operations, HR, procurement, IT, communications. Identify your data owners early and get their buy-in. The single biggest reason first reports go badly is that the team responsible for the report doesn't have the information they need from the rest of the organization.
Run a materiality assessment
Don't try to report on everything. Identify the topics that actually matter — both to your business and to your stakeholders — and focus your reporting energy there.
Map your data sources
Where does your energy data live? Who owns your travel data? What system tracks employee headcount? You'll need to pull from utility bills, ERP systems, HR systems, procurement systems, fleet management tools, and travel booking platforms. Knowing where the data lives is half the battle.
Set your boundaries and base year
Decide which entities and operations are in scope, which methodology you're using (operational control, financial control, equity share), and what year you're using as your baseline for tracking progress over time.
Calculate, draft, review, publish
Once the foundations are in place, the actual work of producing a report becomes much more tractable. You calculate the numbers, draft the narrative sections, review internally, address any assurance requirements, and publish.
This is a meaningful amount of work for a first time, but it's not magic, and it's not work that requires a sustainability degree. Most teams that successfully publish a first sustainability report did so by being disciplined and methodical, not by hiring an army of consultants.
Where to go from here
This guide is the entry point. From here, the natural next steps depend on what you've decided you need to do:
- If you're trying to choose between GRI, IFRS, and GHG Protocol, the Choosing your first framework guide walks through the decision in more depth.
- If materiality is the next thing you need to figure out, Building a materiality assessment from scratch is the practical playbook.
- If you're focused on emissions specifically, Setting your base year and reporting boundaries covers a foundational step most first-time reporters get wrong.
- If you want a quick overview of what's coming in 2026 and beyond, the latest articles round up the latest developments.
Sustainability reporting is one of those things that looks intimidating from the outside and turns out to be tractable once you've done it once. The frameworks are well-documented. The methodology is established. The pitfalls are known. What's required is some discipline, a reasonable amount of cross-functional coordination, and a tool that lets you focus on the substance instead of fighting your spreadsheets.