Non-financial information assurance: a review of the literature and directions for future research

Purpose This study aims to review the literature on non-financial information (NFI) assurance including external assurance of sustainability reports (SRA) and integrated reports (IRA). The objectives are as follows: provide an overview of academic research; understand the nature of NFI assurance engagements by organising the literature around the five key elements of an assurance engagement; develop a framework for understanding NFI assurance; and provide directions for future research. Design/methodology/approach The study undertakes a structured literature review of 179 articles published from 1999 to 2023. Findings The review identified 324 researchers located in 35 different countries who published 179 articles on SRA and IRA. The researchers, their locations, journals, methods, theories and themes are examined. The literature is structured around the definition of an assurance engagement including a tripartite arrangement, subject matter, a suitable criterion, sufficient appropriate evidence and a written assurance report. A framework for understanding NFI assurance is offered. Avenues for future research, structured around the five elements of an assurance engagement, are presented. Practical implications Researchers will benefit from an overview of the literature and guidance on areas for future research. Lecturers can use the findings to develop content for their auditing courses. Reporting managers will benefit from a better understanding of this new form of assurance. Regulators can use this study’s insights to better inform the development of laws and corporate governance codes mandating NFI assurance. Standard setters can use these findings to guide the emergence of the new assurance standards. Assurance practitioners may use this research to inform practice. Social implications The findings may prove useful in addressing capture, which deters NFI assurance from enhancing disclosure credibility and fulfilling its transparency and accountability role. This is to the detriment of the wider society. Originality/value The consolidation of the literature around the five key elements of an assurance engagement is unique. The framework devised offers useful insights into the dynamics of assurance generally and NFI assurance more specifically. The study is timely given the new European Union regulations on NFI reporting and assurance and the work of the International Audit and Assurance Standards Board in developing a specialist NFI assurance standard.