The external assurance of ESG reports in Poland on the example of companies from the WIG20 index

Purpose: The article identifies the basic practices that audit companies use when auditing ESG reports in Poland after 2017. Methodology/approach: The study covered 120 ESG reports published by companies included in the WIG20 index between 2017 and 2022. The first stage of the research involved selecting companies from the research sample whose reports were externally audited. The second stage involved analyzing the contents of the assurance reports. The article also used bibliometric analysis, a critical literature review, comparative analysis, and induction and synthesis methods. Findings: The empirical research shows that out of 120 sustainability reports, only 36 were externally audited. A detailed analysis allowed the identification of audit firms’ basic practices: (1) the most common reference is to a report from an independent assurance service with limited certainty, (2) half of the reports were prepared by the “Big Four”, (3) all reports followed the International Standard for Assurance Services 3000, (4) the most common subject of the audits was GRI indicators, which were listed exhaustively in the report.Research limitations/implications: The research was conducted on a relatively small sample – only companies from the WIG20 index; additionally, the time scope of the research only covered reports from 2017–2022.Originality/value: The article contributes to the Polish literature on the subject but also has practical significance. The results of the empirical study indicate that audit reports are created with a large degree of freedom, which may negatively affect their cognitive value and comparability.