Companies in India are now reporting ESG data not just for compliance but also for trust and clarity. The BRSR framework makes this process more formal through defined indicators along with a push for third-party assurance. For listed companies, the difference between an internal review and an external opinion is now part of regulatory expectations. Knowing how assessment works along with how limited and reasonable assurance compare is the first step to preparing your ESG report the right way. Why assurance matters in ESG reporting Assurance brings structure to how companies report non-financial data. It helps confirm that the data is correct along with consistent across time periods and reporting boundaries. The SEBI BRSR Core framework makes assurance mandatory for certain ESG indicators. This rule will apply to the top 1,000 companies in India by financial year 2026–27. That means your team needs to move from internal tracking to verified reports that others can rely on. What assessment means and what it covers ESG assessment is usually conducted at the initial stage of reporting. It assists in mapping the most important things as well as missing data. The company can do this on its own or through a consulting partner. Assessment assists in developing the report, but not the degree of review that is associated with assurance. It is useful in preparation and planning but is not considered as formal validation under BRSR. How limited assurance works Limited assurance is a third-party review that checks if the report contains major issues or clear mistakes. It relies on small samples along with interviews and does not go very deep. The final opinion is usually written as a negative statement. It says that no material misstatements were found but does not confirm full accuracy. Limited assurance is common in early-stage ESG reporting or when regulations do not ask for full verification. What reasonable assurance includes Reasonable assurance is a deeper and more structured review. The third party tests the company’s systems along with the data and the process behind it. They look at how the company collects information and whether it can be traced to a valid source. This level of assurance ends with a positive statement which confirms that the data is accurate based on the review. It is the only level accepted for the mandatory BRSR Core indicators under SEBI’s rule. SEBI’s assurance timeline SEBI has introduced a clear path for how companies will move into reasonable assurance. The indicators covered include emissions, energy, water, waste, safety, workforce and other core metrics that can be verified through data. What companies need to be ready Reasonable assurance cannot be done in a rush. Your company needs strong records along with consistent reporting systems. Every ESG metric should have a clear owner and a method that can be reviewed. You also need to know which KPIs are required and whether the data is available across your operations and value chain. Any gaps should be fixed before the review begins. Where GRI reporting supports assurance GRI is a voluntary reporting system but it offers a structured way to manage ESG data. It helps define what matters and builds a path to deeper reporting. Since SEBI’s BRSR Core is now mandatory, GRI can help support the process by offering detail, clarity and context. The GRI and BSE mapping document also shows which GRI indicators match BRSR disclosures. Using both together helps create a report that is easier to assure. How companies are using both GRI and BRSR Many companies now use GRI to build out the full report and meet global stakeholder needs. They then use the BRSR Core as the base for compliance. GRI adds materiality along with narrative and policy detail which helps support the assurance process. This approach reduces confusion and gives companies a way to meet local rules and global expectations without writing two separate reports. Key differences between the three levels Review Type Done By Depth of Review Accepted for BRSR Core Assessment Internal or advisory firm High-level scan of data and gaps No Limited Assurance Independent third party Surface-level testing with limited scope No Reasonable Assurance Independent third party Deep testing of data and controls Yes Steps to prepare for reasonable assurance • Check which BRSR Core KPIs need assurance and map them to your internal data • Assign owners across departments to manage data sources and tracking • Use mock audits to check whether data is traceable and policy support is clear • Apply GRI to add structure and consistency across topics and metrics • Work with your assurance partner early to avoid issues during final review Why this shift matters now Assurance is no longer optional for many companies in India. Investors along with regulators, want ESG data that can be trusted. Limited assurance may work for general reportin,g but will not meet the standard now required under BRSR Core. Companies that wait too long to prepare may face last-minute pressure or risk non-compliance. How Indian Register Quality Systems can support your team Indian Register Quality Systems works with companies that need support across all three levels. Whether you are building your first ESG report or preparing for reasonable assurance, our team helps you move step by step. With clear planning and careful delivery, we help you meet SEBI requirements without added confusion or wasted time. FAQs What is the difference between assessment and assurance in ESG reporting? Assessment helps you review ESG practices and identify gaps while assurance checks if your data is accurate and ready to meet external reporting rules. Does SEBI require limited assurance or reasonable assurance for BRSR Core? SEBI requires companies to obtain reasonable assurance for specific ESG indicators under BRSR Core and does not accept limited assurance for those metrics. Can a company use GRI reporting to support BRSR compliance? Yes, using GRI helps companies structure their ESG data and supports BRSR disclosures with clear topics along with globally recognised reporting standards. Who is required to follow BRSR Core