Mexico's ISSB Moment: Sustainability Disclosures Become Securities-Market Regulation

Mexico has transitioned from voluntary ESG reporting to a securities-market requirement anchored in the ISSB Standards. In January 2025, the National Banking and Securities Commission (CNBV) published modifications to the Circular Única de Emisoras (CUE), incorporating IFRS Sustainability Disclosure Standards by reference (IFRS S1, IFRS S2, and future ISSB standards). These requirements apply to issuers of equity, debt, and other securities supervised by CNBV, excluding states and municipalities and, for now, listed financial institutions.

The Timeline

The modifications to the CUE took effect on January 29, 2025. Issuers other than financial institutions must present sustainability-related financial information for the first time in 2026, covering the 2025 fiscal year. This means 2025 is the build year: establish reporting perimeters, data ownership, methodologies, and internal controls before the first mandatory close.

Why Design Matters

Mexico's approach is explicit about implementation, not just intent. The CUE requires an explicit and unreserved statement of compliance with IFRS Sustainability Disclosure Standards, does not permit dual reporting assertions, and expects disclosures to be published simultaneously with related financial statements. Sustainability-related financial information must be included in a separate annual sustainability report. Together, these design choices prioritize comparability over narrative flexibility.

Four Strategic Priorities

1. Integrate with financial reporting: Treat sustainability disclosure as part of the financial reporting system. Align timelines, controls, documentation, and sign-offs. Design processes that can execute annually, not as a one-time effort.
2. Apply enterprise value materiality: Focus on sustainability-related risks and opportunities that could reasonably be expected to affect cash flows, access to finance, or cost of capital over the short, medium, or long term.
3. Build climate capabilities: IFRS S2 requires scenario analysis, credible transition plans, and metrics and targets that investors can benchmark. These capabilities take time to develop and validate.
4. Prepare for assurance: CNBV's framework is moving toward a phased approach to assurance. Build evidence trails and methodologies now to support future verification requirements.

Beyond the Listed Perimeter

For companies outside the listed perimeter, Mexico's national standard setter (CINIF) published local Sustainability Information Standards (NIS A-1 and NIS B-1) in May 2024, incorporating elements of the ISSB approach and creating a pathway for broader market alignment.

What This Means

Mexico is establishing sustainability disclosure as core capital-markets infrastructure. Companies that build the operational foundation in 2025 will spend 2026 explaining performance rather than defending process. The regulatory framework is designed to drive comparability and accountability, not voluntary storytelling.

Organizations that execute this well will be prepared when the first reporting cycle arrives, with systems that can scale across future ISSB standards and evolving assurance requirements.

If we can be helpful as you consider how these insights will affect your business, please don’t hesitate to reach out to our team.

David Araya, Analyst, Third Economy

david.araya@thirdeconomy.com

Jose Alfaro, Advisor, Third Economy

jose.alfaro@thirdeconomy.com

Disclaimer: The information provided does not, and is not intended to, constitute legal advice; instead, all information, content, and materials available are for general informational purposes only.