South Korea ESG reporting rules: who must disclose from 2028

South Korea will begin mandatory sustainability reporting in 2028 for the largest companies on its main stock market. The first year covers Korea Composite Stock Price Index-listed companies with at least KRW10 trillion in consolidated assets. In 2029, the threshold falls to KRW5 trillion and the expected reporting population expands sharply.

The Financial Services Commission (FSC) says 291 companies and affiliates are expected to fall within the requirement in 2028. One year later, that figure rises to 3,171. The dates matter, but the jump between them is the more immediate preparation problem: data systems, group boundaries and reporting controls will have to spread well beyond the first group of very large listed companies.

The roadmap also gives different parts of the reporting system different start dates. Scope 3 emissions are delayed for three years for each company cohort. Mandatory third-party verification begins in 2030. The legal changes needed to place sustainability disclosures inside statutory corporate business reports still have to pass through the legislative process.

Who must report and when

The final roadmap announced on 8 July 2026 applies to companies listed on South Korea's KOSPI market and uses total consolidated assets to determine the first reporting cohorts. Reports will cover the previous financial year, so the 2028 filings relate to financial year 2027.

The FSC plans to make sustainability information part of the corporate business reports required under the Financial Investment Services and Capital Markets Act (FSCMA). That moves the disclosure from a separate voluntary report towards the statutory reporting system used by investors and regulators.

There is limited first-year relief for consolidated reporting. In a company's first mandatory year, affiliates can be excluded if both their assets and sales are below 10% of the consolidated group totals. That concession may reduce the initial collection burden, but it does not remove the need to map the group and determine which entities meet both conditions.

The steepest expansion comes in the second year

A 2028 start date can make the roadmap look distant and narrowly focused on South Korea's largest groups. The expected coverage numbers tell a different story. Moving from 291 companies and affiliates to 3,171 in one year means preparation cannot be confined to the first mandatory filers.

Large groups will need information from subsidiaries, business units and suppliers before the filing year begins. Companies approaching the KRW5tn threshold will need to know whether growth, acquisitions or group changes could bring them into the 2029 cohort. Businesses outside the legal scope may still receive more structured requests from customers and lenders as those larger companies prepare their own disclosures.

The work is therefore likely to reach finance, risk, procurement, operations and internal audit before it appears in a published sustainability statement. Our guide to sustainability reporting controls explains how ownership, evidence and review turn operational data into a report that can withstand scrutiny.

Scope 3 has its own timetable

Each cohort receives a three-year delay before Scope 3 disclosure becomes mandatory. The largest companies begin in 2031, the KRW5tn cohort in 2032, and a future KRW2tn cohort would begin in 2033. Small and medium-sized businesses that are not high-carbon emitters are expected to be exempt from the Scope 3 duty.

The delay recognises that value-chain emissions are usually the hardest part of a corporate inventory. Companies rely on suppliers, customers, estimates and secondary datasets that sit outside their direct control. A filing deadline can be postponed; the work of building a credible data chain cannot be compressed into the final reporting year.

South Korea plans several pieces of supporting infrastructure by 2028. These include sector guidance for Scope 3 emissions across 15 major export industries, about 1,000 Life Cycle Inventory (LCI) datasets for use when direct supplier data is unavailable, and an industrial supply-chain platform intended to let partner businesses provide data for use by multiple companies.

Those measures should reduce duplication if they are delivered and widely used. Reporting teams will still have to document where primary data ends, where estimates begin and how calculation methods change. The Scope 3 supplier data collection guide sets out the evidence buyers can request without pretending that every supplier already has a complete inventory.

The initial safe harbour does not cover deliberate greenwashing

The roadmap proposes a broad transition period for the first three years. Companies would be exempt from compensation claims, administrative sanctions and criminal penalties under the FSCMA for the sustainability information they file during that period.

That relief is not intended to protect deliberate greenwashing. The FSC says intentional misconduct would still be subject to compensation and administrative sanctions. After the three-year transition, a more targeted safe harbour is planned for inherently uncertain information such as forecasts, greenhouse gas estimates and data collected from partners, provided the disclosure was prepared faithfully, on reasonable grounds and using best judgement.

The practical distinction is between uncertainty and unsupported presentation. Climate scenarios, emissions estimates and supplier data can all contain uncertainty without being misleading. Companies still need records showing the source, method, review and judgement behind the number. A safe harbour is not a substitute for those controls.

Third-party verification begins in 2030

Mandatory third-party verification is scheduled to begin in 2030, two years after the first reporting requirement. The scope of verification and the rules for service providers have not yet been finalised. A government working group will develop the relevant amendments and implementation details.

The gap between first reporting and mandatory verification gives the assurance market time to develop, but it does not make the early reports evidence-light. Data that cannot be traced in 2028 will be difficult to reconstruct when assurance begins. Companies can use the intervening period to test controls, retain calculation files and identify where estimates depend on weak or inaccessible records.

Our guide to limited and reasonable sustainability assurance explains why the level and subject matter of an engagement matter. Korea has announced that verification will be required; it has not yet settled every question about what assurance providers must test.

KSSB standards are the current technical starting point

The Korea Sustainability Standards Board (KSSB) has issued its first two sustainability disclosure standards for voluntary use in 2026. Standard 1 covers general requirements and Standard 2 covers climate-related disclosure. The standards are based on the global baseline developed by the International Sustainability Standards Board (ISSB).

The FSC also plans to update the Korea Exchange (KRX) voluntary disclosure system so companies outside the mandatory scope can report using the KSSB standards. That gives reporting teams a current technical reference while legislation and detailed mandatory rules are developed.

It would be premature to assume that every current voluntary provision will pass unchanged into the final statutory regime. The roadmap fixes the direction and timetable, while legislation, implementation rules, safe-harbour details and verification requirements still have to be completed. The ISSB, IFRS S1 and IFRS S2 guide explains the underlying global architecture, and our SASB Standards guide covers the industry metrics used within that reporting system.

What reporting teams should build before 2028

The roadmap gives companies time, but not spare time. A useful preparation sequence is:

1. Confirm the likely reporting cohort. Track total consolidated assets, listing status and group changes rather than relying on the size of the parent company alone.
2. Map the consolidation boundary. Identify affiliates, data owners and systems, including the smaller entities that may qualify for first-year relief.
3. Assign responsibility for each disclosure. Connect finance, risk, sustainability, procurement, legal and internal audit to named data and review tasks.
4. Build an evidence trail. Retain source records, calculation methods, assumptions, approvals and changes instead of assembling them after the report is drafted.
5. Start value-chain data work early. Use the Scope 3 delay to improve supplier requests and estimation methods, not to postpone the inventory.
6. Run a pre-assurance review. Test whether a reviewer can reproduce material figures and understand the judgements behind forecasts and estimates.

The reporting system will be judged on more than whether a company files on time. Investors, lenders and regulators will need to understand where the data came from, how uncertainty was handled and whether the disclosure agrees with the financial, risk and governance information elsewhere in the business report.

Legislation is the next decisive step

The government intends to prepare amendments to the FSCMA and has said it will move quickly. Those amendments will determine how the roadmap is translated into law. Further rules must also settle verification scope, provider requirements and the permanent safe-harbour design.

Companies can prepare against the announced thresholds and KSSB standards without treating unfinished details as settled. The schedule is clear enough to begin building the reporting system. The remaining legislation will decide exactly how that system is supervised.

Useful source links

• South Korea Financial Services Commission: final sustainability disclosure roadmap
• Korea Sustainability Standards Board: current Korean sustainability disclosure standards
• South Korea Financial Services Commission: background to the domestic disclosure standards
• Feature image: Seoul skyline by NK Lee on Unsplash