Sustainability assurance landscape after the CSRD: Scenario analysis and evolutionary pathways in Europe

This study examines how the evolving European Union sustainability regulatory landscape, shaped by the Corporate Sustainability Reporting Directive (CSRD) and recent developments such as the Stop the Clock Directive and the Omnibus I Package, and embodying differing political, economic, and institutional interpretations of sustainability, may influence the future configuration of the sustainability assurance market for both mandatory and voluntary adopters. The paper adopts a scenario analysis approach, supported by an inductive content analysis of legislative texts related to CSRD transposition and the Omnibus I Package. Key variables, including the scope of authorised providers, the role of incumbent auditors, professional qualifications, and training requirements, guide the construction of alternative scenarios. For mandatory adopters, the analysis outlines three possible trajectories for the sustainability assurance market: (1) a monopoly of statutory auditors, (2) competitive coexistence between statutory auditors and independent assurance service providers (IASPs), and (3) thematic specialisation between financial and sustainability auditors. For voluntary adopters, the analysis adds (4), a fragmented and largely optional assurance market shaped by the Omnibus I framework. The scenarios identify actionable regulatory levers that policymakers and oversight bodies can use to mitigate fragmentation risks and safeguard assurance quality under both mandatory and voluntary regimes. By clarifying how regulatory recalibration may affect sustainability assurance practices, the study informs stakeholders who rely on sustainability reports for accountability and decision-making. This study presents a novel approach by employing scenario analysis to link the diversity of CSRD implementation with potential assurance market outcomes. By connecting expected divergence in CSRD transposition to broad political and sustainability dynamics within the EU, the study demonstrates how competing policy directions and differing emphases on the economic, social, and environmental pillars shape the emerging assurance market.