South Korea’s phased climate disclosure mandate signals accelerated ESG compliance push

South Korea is moving to make climate-related financial disclosures consistent with the ISSB framework, advancing a phased mandate that will affect the country’s largest listed companies and ripple through industrial decarbonisation plans.

According to Practical ESG, the Financial Services Commission has issued a draft roadmap that would require KOSPI-listed firms with consolidated assets above KRW 30 trillion (about USD 20.4 billion) to begin ISSB-aligned sustainability reporting in 2028, using 2027 data. “Under the new proposed roadmap, companies listed on Korea’s benchmark KOSPI Index with assets greater than KRW 30 trillion (USD$20.4 billion) will be required to begin sustainability reporting in line with the new standards in 2028, based on 2027 data. The roadmap envisions potentially expanding reporting requirements to KOSPI-listed companies with more than KRW 10 trillion in assets (USD$6.8 billion) one year later, with possible further expansion to smaller firms depending on readiness and international developments,” ESG Today reports.

That staged approach aligns with reporting design published elsewhere: local outlets say the threshold will fall to companies with KRW 10 trillion of assets in 2029, and Scope 3 emissions disclosure is slated to begin in 2031 with limited exemptions for smaller enterprises, according to a report in The Seoul Economic Daily. The Korea Accounting Standards Board is completing domestic standards built on the ISSB model to support the rollout.

South Korea’s domestic standards , variously described as KSSB or K-IFRS Sustainability Disclosure Standards , map to the ISSB’s IFRS S1 and S2, covering governance, strategy, risk management and metrics. Industry analysis notes the framework includes requirements specific to financial institutions such as financed emissions and addresses transition and physical climate risks as well as opportunities. At the same time, legal and advisory commentary highlights that regulators have chosen not to adopt every IFRS provision verbatim; some local deviations remain under consultation and could affect the final scope and timing of obligations.

There is some variance in reporting timelines reported by different sources. Regulatory and consultancy briefings indicate a phased implementation that may see certain large entities begin disclosures earlier, while other summaries have pointed to FY2026 start dates for particular elements. The IFRS Foundation’s jurisdictional overview, published in mid‑2025, shows more than three dozen jurisdictions adopting or moving toward ISSB-based rules, situating Seoul’s plan within a broader global convergence.

For industrial players, the practical consequences are immediate. Firms that meet the asset thresholds will need to assemble the governance, data systems and assurance arrangements required by ISSB-style disclosures well before the first reporting year. The delayed start for mandatory Scope 3 reporting until 2031 gives buyers and suppliers additional time to align data collection and verification, but it also raises transitional risks for companies that rely on supply‑chain emissions reductions to meet near‑term targets. Financial institutions should expect earlier demands to quantify financed and insured emissions, prompting changes to risk assessment and capital allocation processes.

Officials and market participants have framed the roadmap as responsive to international developments and corporate readiness. The final contours of the standards, and any exemptions or local departures from ISSB texts, will depend on the Korea Sustainability Standards Board’s consultations and the FSC’s decisions as the timeline is finalised.

As jurisdictions worldwide converge on ISSB-based disclosure regimes, South Korea’s phased mandate will intensify pressures on large listed companies and their supply chains to produce reliable climate data, integrate transition planning into financial filings and secure independent assurance. For industrial decarbonisation professionals, the immediate task is operationalising data flows and governance to satisfy the coming disclosure regime while managing the commercial and regulatory risks of a rolling expansion from the largest corporates to smaller listed firms.