Guest post by: Aaron Saw, Head of Corporate Reporting Insights – Financial, ACCA
As expectations around sustainability reporting continue to rise, many organisations are discovering a fundamental challenge: the data isn’t ready.
Across complex value chains, sustainability information is often incomplete, uncertain, or simply unavailable. Yet the pressure to disclose continues to increase. Regulators, investors and stakeholders are demanding clear, decision-useful information – even when the underlying data is still evolving.
This creates a tension at the heart of modern reporting: how do you provide credible insights when there’s so much uncertainty?
Why waiting is not an option
In my view, waiting for perfect data is not a viable option. For many organisations, the challenge is not a lack of ambition – it is a lack of complete data. Sustainability reporting is still developing, and globally consistent measurement approaches are not yet fully established. Uncertainty is not the exception – it is the norm.
Against this backdrop, estimates are a necessary part of the reporting process. Whether drawing on proxy data, third-party sources or assumptions based on financial and operational information, organisations are already using estimates to build a picture of their sustainability performance. Without them, many disclosures simply would not be possible.
The question, therefore, is no longer whether estimates should be used, but how they should be used responsibly.
Building trust through transparency
There is a risk that estimates, if poorly applied, could undermine trust. A lack of transparency around assumptions, inconsistent methodologies, or weak governance can create doubt for users of sustainability information. But we should be clear: estimates themselves do not undermine trust – poor practice does.
Credibility in sustainability reporting comes from how uncertainty is handled.
Organisations that approach this well tend to share common characteristics. They are transparent about assumptions and limitations. They apply appropriate governance and controls. And they integrate sustainability data into wider systems, rather than treating it as a standalone exercise. Just as importantly, they recognise that estimates are not static.
As understanding of a sustainability topic improves and better-quality data becomes available, estimates should be refined. This iterative approach allows organisations to enhance disclosures over time while still meeting current expectations. Value chains remain a particular challenge. Gathering reliable data across multiple partners and systems is complex, and progress will depend on greater coordination and collaboration.
A bridge to better reporting
In the meantime, estimates provide a practical bridge between current reality and future ambition. For finance professionals, this is familiar territory. Assumptions, judgment, control and transparency have long been central to financial reporting – and those same principles now apply to sustainability reporting. This perspective is further explored in ACCA’s report, “Sustainability reporting: working with estimates”, which highlights how organisations are using reasonable and supportable assumptions to create decision-useful information when data is incomplete or uncertain.
Ultimately, sustainability reporting is not about achieving perfection from the outset. It is about providing decision-useful information that explains how an organisation manages its exposure to uncertainties arising from its activities. Organisations that wait risk falling behind. Those that act now – using reasonable, well-governed estimates – will be better placed to respond to uncertainties as the natural, social and economic environments continue to evolve.
Be proactive in leading the change.
