Ask three BRSR practitioners what "BRSR Core" means and you will get three different answers. The terminology is genuinely confusing, and SEBI's own circulars have not always used the terms consistently. Here is a clear breakdown.
BRSR Essential: the full format
BRSR Essential refers to the full BRSR reporting format as prescribed by SEBI in its 2021 circular (as amended). It covers all three sections:
- Section A: General disclosures (company details, products, operations, employees).
- Section B: Management and process disclosures (policies, targets, governance).
- Section C: Principle-wise performance disclosures (108 indicators across P1-P9, split into Essential and Leadership indicators).
All companies to which BRSR applies must file BRSR Essential in their Annual Report. No assurance is mandated for Essential-only filers, though companies can voluntarily arrange limited assurance.
BRSR Core: the 42 KPIs that need assurance
BRSR Core is a curated sub-set of 42 Key Performance Indicators drawn from the full BRSR Essential format. SEBI identified these 42 KPIs as the most material and quantifiable disclosures across the 9 BRSR principles.
BRSR Core ≠ a separate report
| BRSR Essential | BRSR Core | |
|---|---|---|
| Scope | Full format, all 108 Section C indicators | 42 KPIs drawn from Section C |
| Assurance | Not mandated | Reasonable assurance required |
| Mandatory for | Top 1000 listed companies (since FY 2022-23) | Top 500 (FY 2025-26); top 1000 (FY 2026-27) |
| Who assures | N/A (voluntary) | SEBI-registered assurance provider |
What reasonable assurance requires
Reasonable assurance is a high bar. The assurer must obtain sufficient evidence to express a positive opinion: "In our opinion, the 42 Core KPIs are free from material misstatement." This contrasts with limited assurance, which is a negative opinion ("nothing came to our attention to suggest...").
To support a reasonable assurance engagement, your client will typically need:
- Primary source data for each KPI (meter readings, HR system exports, purchase invoices).
- Documented calculation methodology with emission factor citations.
- An internal sign-off trail: who compiled the data, who approved it.
- Evidence of the data at a site level before aggregation to company level.
Practical advice for consultants
If your client is in the top 500, raise the assurance requirement in your kickoff meeting. Build the data trail from day one, it costs almost nothing extra during data collection but can save weeks of rework if the assurer asks for evidence later. And choose the assurer early: SEBI-registered ESG assurers have limited capacity and are booking out months in advance as the Core mandate expands.
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