India's Business Responsibility and Sustainability Report (BRSR), mandated by the Securities and Exchange Board of India (SEBI) for the top 1,000 listed companies by market capitalisation, has crossed a threshold familiar from financial reporting: from disclosure you assert to data someone independently checks. The mechanism is BRSR Core.
What BRSR and BRSR Core are
The full BRSR is a structured report covering the nine principles of India's National Guidelines on Responsible Business Conduct (NGRBC), spanning environment, social and governance disclosures. BRSR Core is a defined subset of that report — a focused set of key performance indicators and attributes (covering areas such as greenhouse-gas intensity, energy, water, waste, and key social metrics) that SEBI has singled out as requiring reasonable assurance. In other words: the whole BRSR is reported; the Core is reported and assured.
The assurance timeline is phased
- Reasonable assurance of BRSR Core is being phased in by market-capitalisation rank, beginning with the largest companies and widening each year.
- The phase-in started with the top-ranked listed companies and is scheduled to extend toward the top 1,000 over subsequent financial years.
- SEBI has adjusted the timeline and scope during implementation, so the precise applicability date for your company should be confirmed against the latest SEBI circular.
The value-chain dimension
BRSR Core did something else significant: it introduced ESG disclosure for the value chain. In-scope companies are expected to report Core KPIs for their significant upstream and downstream partners (defined by a share of purchases and sales), on a phased, comply-or-explain basis. The ripple effect is the important part — requirements that formally land on a listed company flow straight to its unlisted suppliers, who must now produce the underlying data. If you supply a large Indian listed company, BRSR Core reaches you even if you never file one yourself.
Why Core plus reasonable assurance is the hard part
Reasonable assurance is a materially higher bar than limited assurance. Limited assurance yields a negative-form conclusion (nothing came to our attention); reasonable assurance yields a positive opinion, and demands substantially more evidence, controls testing and data traceability. Most first-time difficulties are not performance problems — they are evidence and control gaps: numbers that cannot be traced from source to disclosure, or processes with no documented controls. Those are fixable, but far cheaper to fix before the assurer arrives than during the engagement.
How to prepare
- Identify which Core KPIs apply to you and where the data currently comes from.
- Build the data systems, controls and source-to-disclosure lineage that reasonable assurance requires.
- Run a readiness or gap assessment against the assurance standard before the live engagement.
- Engage value-chain partners early — their data is now part of your disclosure.
- Align the work with IFRS S1/S2, which overlaps heavily, so the same backbone serves both Indian and global requirements.
BRSR requirements and timelines are set and periodically revised by SEBI; confirm the current obligations and dates in the latest SEBI circulars before acting.
Sources & further reading
This article is general information, not legal, financial or compliance advice. The regulations and standards referenced here evolve; verify the current position with the issuing body, or ask us. Published June 2026.