Sustainability accounting: how to build and deliver reporting services in your practice

Published Thursday 11 June 2026

Table of contents

• UK sustainability reporting requirements
• Sustainability reporting frameworks and standards
• Building sustainability accounting into your practice
• Guiding clients through sustainability reporting
• Sustainability assurance and advisory opportunities
• Sustainability accounting tools in Xero
• Strengthen your sustainability services with Xero
• FAQs on sustainability accounting

Key takeaways

• UK Sustainability Reporting Standards S1 and S2 were published in February 2026, giving practices a clear framework to build services around before mandatory requirements take effect.
• Sustainability accounting draws on skills you already have in data collection, assurance, and client advisory, so the transition is about applying existing expertise to new reporting demands.
• Early movers can position their practice for sustainability assurance engagements under ISSA (UK) 5000, which becomes effective for periods beginning on or after 15 December 2026.
• Xero's reporting features and app marketplace integrations can help you streamline emissions tracking and sustainability data management for your clients.

UK sustainability reporting requirements

The regulatory landscape for sustainability reporting in the UK has shifted considerably over the past two years. Understanding the current requirements and what is coming next is essential if you want to advise clients with confidence and build a credible service offering.

Who must report now

Mandatory climate-related financial disclosures currently apply to UK-listed companies and public interest entities with 500 or more employees. Large private companies with more than 500 employees and over £500 million in annual turnover are also in scope. These disclosures were originally aligned with TCFD recommendations, but the landscape has evolved.

The shift from TCFD to ISSB

The Task Force on Climate-related Financial Disclosures (TCFD) formally disbanded in October 2023, with the International Sustainability Standards Board (ISSB) taking over responsibility for monitoring corporate climate disclosures. The Climate Disclosure Standards Board (CDSB) merged into the IFRS Foundation in January 2022, further consolidating the standard-setting landscape under the ISSB umbrella.

UK SRS S1 and S2

In February 2026, the UK government published UK Sustainability Reporting Standards S1 and S2, based on the ISSB's global baseline. These standards are currently available for voluntary adoption. A separate consultation on mandatory application is expected later in 2026, so the direction of travel is clear even if the final timeline has not been confirmed.

For your practice, this means there is a window to build capability and start advising clients before compliance becomes compulsory. Firms that move early will be better placed to handle the surge in demand once mandatory requirements are confirmed.

Sustainability reporting frameworks and standards

Choosing the right reporting framework depends on your client's size, sector, and stakeholder expectations. Here is how the major frameworks compare and where they fit.

Global Reporting Initiative (GRI)

GRI standards remain the most widely used sustainability reporting framework globally. They cover three pillars: economy, environment, and people. GRI is particularly useful for clients who want to report on broad sustainability impacts beyond climate, including labour practices, community engagement, and governance.

IFRS S1 and S2

IFRS S1 sets out general sustainability-related disclosure requirements, while IFRS S2 focuses specifically on climate-related disclosures. Together they form the ISSB's global baseline and underpin the UK SRS. For UK-focused practices, these are the standards to prioritise.

SASB standards

SASB standards, now maintained by the ISSB under the IFRS Foundation, provide industry-specific disclosure guidance. They are valuable when clients need to identify the sustainability topics most material to their sector.

Choosing the right framework

There is no single correct choice. Many organisations use a combination of frameworks. The ICAEW's guide to ESG reporting frameworks is a practical starting point for comparing options and advising clients on which approach suits their circumstances. Consider your client's reporting obligations, investor expectations, and the sectors they operate in when making recommendations.

Building sustainability accounting into your practice

Adding sustainability accounting to your service menu does not require starting from scratch. Much of the groundwork sits in skills your practice already uses daily. The challenge is packaging those skills into a distinct, marketable offering.

Transferable skills you already have

Sustainability reporting relies heavily on competencies that are core to accounting and bookkeeping work:

• Data collection and validation. Gathering emissions data, energy usage, and supply chain metrics follows the same discipline as collecting financial data for year-end accounts.
• Materiality assessment. Determining which sustainability topics are material to a client mirrors the materiality judgements you make in financial reporting.
• Assurance and verification. If your practice already handles audit or review engagements, the step to sustainability assurance is smaller than you might expect.
• Advisory and interpretation. Translating complex requirements into plain-language guidance for clients is something you do with tax and compliance already.

Developing your service offering

Start by defining the scope of services you want to provide. Common entry points include:

• Sustainability readiness reviews. Assess where a client stands against current and upcoming requirements.
• Carbon footprint measurement. Help clients quantify Scope 1, 2, and 3 emissions using their existing financial and operational data.
• Report preparation. Draft sustainability disclosures aligned with UK SRS, GRI, or other relevant frameworks.
• Ongoing advisory. Provide quarterly or annual sustainability performance reviews, target setting, and improvement recommendations.

Pricing sustainability services

Sustainability accounting is advisory work, so value-based pricing often makes more sense than hourly rates. Consider the complexity of the engagement, the client's size and sector, and the level of assurance required. Package introductory services at a lower price point to build the relationship, then upsell into ongoing advisory and assurance as the client's reporting matures.

Guiding clients through sustainability reporting

Your clients will look to you for clarity on what they need to do, when, and how. Positioning yourself as their sustainability adviser starts with understanding where they are now and what they need to achieve.

Assessing client readiness

Before diving into reporting, help clients understand their starting point. A readiness assessment typically covers:

• Current data availability. What environmental, social, and governance data does the client already collect, and where are the gaps?
• Regulatory exposure. Is the client currently in scope for mandatory disclosures, or is it preparing ahead of anticipated requirements?
• Stakeholder expectations. Are investors, lenders, or customers asking for sustainability information?
• Internal capacity. Does the client have staff who can own the data collection process, or will they need your ongoing support?

Environmental, social, and governance factors

Guide clients to think about sustainability across all three dimensions. Environmental factors include carbon emissions, energy consumption, waste management, and water use. Social factors cover workforce practices, diversity, health and safety, and community impact. Governance factors address board oversight of sustainability risks, ethical conduct, and supply chain due diligence.

Not every factor will be material to every client. Your role is to help them focus on what matters most for their sector and stakeholders, rather than trying to report on everything at once.

Common challenges

Clients often struggle with data quality, particularly for Scope 3 emissions that span their supply chain. Many also lack internal processes for collecting non-financial data consistently. Set realistic expectations early: sustainability reporting improves over time, and a first report does not need to be perfect. It needs to be honest, structured, and built on a foundation that can be refined in subsequent periods.

Sustainability assurance and advisory opportunities

As sustainability reporting becomes more established, demand for independent assurance is growing. This represents a significant opportunity for practices that invest in the right capabilities now.

ISSA (UK) 5000

The Financial Reporting Council (FRC) has published ISSA (UK) 5000, a standard for sustainability assurance engagements. It becomes effective for periods beginning on or after 15 December 2026. This standard provides a structured framework for assurance providers, covering both limited and reasonable assurance over sustainability information.

If your practice already performs audit or assurance work, ISSA (UK) 5000 builds on familiar concepts. The key difference is subject matter expertise: you will need to demonstrate competence in sustainability topics, not just in assurance methodology.

Growing demand for assurance

Investors and regulators increasingly expect sustainability disclosures to carry the same level of rigour as financial statements. As mandatory reporting expands, so will the requirement for independent assurance. Practices that develop sustainability assurance capabilities early will have a competitive advantage when demand accelerates.

Positioning your practice

Consider these steps to prepare for sustainability assurance engagements:

• Upskill your team. Invest in CPD focused on sustainability reporting standards, climate science basics, and assurance methodology for non-financial data.
• Build a track record. Start with advisory and report preparation engagements to develop subject matter expertise before taking on full assurance mandates.
• Develop quality management processes. Sustainability assurance requires the same rigour around independence, documentation, and quality control as financial audit.
• Engage with professional bodies. ICAEW, ACCA, and other bodies offer resources and guidance on ESG reporting and sustainability assurance readiness.

Sustainability accounting tools in Xero

Effective sustainability accounting depends on having the right tools to collect, manage, and report on environmental data alongside your financial workflows. Xero's platform and app marketplace offer several options to support this.

Reporting features

Xero's reporting and analytics tools can help you track financial data that feeds into sustainability disclosures. Energy costs, travel expenses, and waste management spending are already captured in your client's accounts. Categorising and extracting this data systematically gives you a financial baseline for carbon footprint calculations and other environmental metrics.

App marketplace integrations

Several apps in the Xero marketplace connect directly to your client's accounting data to automate emissions tracking and sustainability reporting:

• Zero Carbon. Calculates carbon footprints using transaction data from Xero, making it straightforward to measure Scope 1, 2, and 3 emissions without manual data entry.
• Greenly. Provides carbon accounting and climate action planning, integrating with Xero to pull financial data for emissions analysis.
• Sumday. Offers sustainability measurement tools that connect to Xero, helping clients track and reduce their environmental impact over time.
• CarbonInvoice. Adds carbon footprint data to invoices, giving clients visibility of the emissions associated with their purchases and sales.

These integrations reduce the manual effort involved in gathering sustainability data and make it easier to deliver consistent, accurate reports to clients.

Strengthen your sustainability services with Xero

Building a sustainability accounting offering takes the right combination of expertise, tools, and client relationships. The Xero Partner Programme gives you access to free practice-use software, Xero HQ for managing your client portfolio, and a growing range of sustainability-focused app integrations. Whether you are starting with carbon footprint measurement or working towards full sustainability assurance, having your financial and sustainability data connected in one platform makes the work more efficient and the insights more reliable.

Join the partner programme

FAQs on sustainability accounting

Here are some frequently asked questions about sustainability accounting.

Do small and medium-sized businesses need sustainability reports?

Most SMBs are not currently subject to mandatory sustainability reporting requirements in the UK. However, many are being asked for sustainability data by larger clients in their supply chain, lenders, or insurers. Advising smaller clients on voluntary reporting can help them meet these requests and prepare for future requirements.

What is the difference between limited and reasonable assurance for sustainability reports?

Limited assurance provides a moderate level of confidence that sustainability information is free from material misstatement, typically through inquiry and analytical procedures. Reasonable assurance provides a higher level of confidence and involves more extensive evidence-gathering, similar to a financial statement audit. ISSA (UK) 5000 covers both levels.

How do the UN Sustainable Development Goals relate to sustainability reporting?

The UN SDGs provide a global framework of 17 goals covering areas such as climate action, decent work, and responsible consumption. While they are not a reporting standard, many organisations use the SDGs to frame their sustainability strategy and demonstrate how their activities contribute to broader societal objectives.

Can sustainability accounting services be offered remotely?

Yes. Much of the data collection, analysis, and reporting involved in sustainability accounting can be done using cloud-based tools. Xero's platform and its app integrations allow you to access client financial data remotely, which supports efficient delivery of sustainability services regardless of location.

What qualifications support a move into sustainability accounting?

Professional bodies including ICAEW, ACCA, and ICAS offer CPD modules and certificates in sustainability reporting and assurance. The ISSB's materials on IFRS S1 and S2 are also valuable self-study resources. Practical experience through advisory engagements builds credibility alongside formal qualifications.