ICAEW and the World Business Council for Sustainable Development (WBCSD) have launched a second edition of A buyer’s guide to assurance on sustainability information – a practical resource to help organisations commission and use assurance with confidence.

Aimed at boards, audit committees, CFOs and sustainability leaders, the guide aims to support clearer decision-making, stronger engagement with assurance practitioners and a proportionate approach as reporting matures.

For ICAEW members, it comes at a time of rising expectations around the reliability of sustainability information and the role of assurance in building trust.

The guide was launched during London Climate Action Week, reflecting growing demand for high-quality, decision-useful sustainability reporting.

A buyer’s perspective on assurance

As sustainability reporting evolves, expectations of credibility are rising, but assurance remains difficult for many organisations to navigate.

The guide takes a buyer’s perspective, helping organisations move from uncertainty to informed action. It answers key questions, including:

• what assurance is, and is not,
• how to determine the right scope and level of assurance,
• what to look for in an assurance practitioner, and 
• how assurance can strengthen processes and decision-making.

It recognises that organisations are at different stages of maturity and supports a structured, approach to building assurance over time.

From compliance to strategic value

Assurance builds trust, not just compliance. As sustainability information becomes embedded in strategy, it plays a key role in:

• strengthening governance,
• improving data quality, and
• supporting decision-useful reporting.

A lively panel discussion at the launch explored the opportunities and challenges of sustainability reporting and assurance, reflecting a range of perspectives across the market.

ICAEW’s Chief Executive, Alan Vallance, said: “Sustainability information needs to stand up in the boardroom and support robust decision-making. Independent assurance acts as a critical friend, challenging, strengthening and building confidence in the information that underpins strategy, governance, and disclosures.”

Closing the gap between expectations and reality

Despite growing momentum, adoption remains uneven. Organisations face evolving regulation, competing priorities, variable data maturity and rising stakeholder expectations.

There can be a gap between what users expect and what assurance delivers. The guide addresses this by emphasising that high-quality assurance depends on:

• strong systems and controls,
• clear governance and accountability, and
• informed decision-making by those commissioning assurance.

It also reinforces that assurance does not guarantee perfection or replace management responsibility. Its value lies in independent challenge, transparency and continuous improvement.

Supporting a credible assurance ecosystem

The guide contributes to wider efforts to build a credible sustainability assurance market. While progress on global standards, including ISSA 5000, is significant, outcomes depend on how they are applied in practice.

There is growing recognition that:

• organisations need stronger governance, data and control frameworks,
• greater regulatory clarity and consistency is essential, and
• capability and capacity must continue to develop.

ICAEW is supporting this through policy engagement, collaboration with regulators and standard setters, and investment in training and capability.

A practical tool for boards and management

At its core, the guide is a practical resource.

For boards and audit committees, it strengthens oversight and supports more effective challenge on the reliability of sustainability information.

For management, it provides a clear framework for building systems, processes and controls, and for taking a structured approach to assurance from the outset.

By focusing on real-world decisions, it positions assurance as part of a broader shift towards more robust, decision-useful reporting.