BRSR Core Reporting: A Practical Guide for Listed Companies and Their Value Chains

BRSR Core reporting is a defined subset of ESG disclosures within the Business Responsibility and Sustainability Report that SEBI requires listed companies to have independently assured. Introduced through a July 2023 SEBI circular, it applies on a phased basis to the top 1000 listed companies and cascades to their value chain partners.

When Your ESG Numbers Suddenly Need an Auditor

Your sustainability report has always been a narrative. You described your emissions, your workforce practices, your community work, and nobody questioned the figures. Then a SEBI requirement changes the rules. A defined set of those numbers now needs independent assurance, and a customer higher up your supply chain starts asking you for the same data in the same format.

This shift is already underway for listed companies in India and the businesses that supply them. BRSR Core reporting moves ESG disclosure from self declared statements to independently checked data. This guide explains what BRSR Core covers, who it applies to, how the value chain effect works, and how to prepare before the deadline reaches you.

What you will learn:

• What BRSR Core is and how it differs from the full BRSR
• Who must comply and when
• Why the value chain requirement affects unlisted suppliers
• How third party assurance works and how to prepare for it

What BRSR Core Reporting Actually Is

BRSR Core is a subset, not a separate report. It sits inside the wider Business Responsibility and Sustainability Report (BRSR) that certain listed companies already file.

The Securities and Exchange Board of India (SEBI) introduced the framework through circular SEBI/HO/CFD/CFD-SEC-2/P/CIR/2023/122, dated 12 July 2023. That circular set out the BRSR Core as a framework for assurance and ESG disclosures for the value chain.

The important word is assurance. The full BRSR contains a broad range of ESG disclosures, many of them descriptive. BRSR Core identifies a focused set of key performance indicators (KPIs) that must be backed by independent checking rather than self declaration.

It would therefore be inaccurate to suggest that the entire BRSR requires assurance. The assurance requirement applies to the BRSR Core, a defined subset of ESG KPIs, not to every disclosure in the report.

How BRSR Core Differs From the Full BRSR

The two documents are connected but serve different purposes.

The full BRSR captures a company’s wider sustainability story. It covers governance, environmental performance, social practices, and the company’s approach across the National Guidelines on Responsible Business Conduct. Much of it is narrative and self reported.

BRSR Core narrows the focus to specific, measurable indicators. These include quantitative KPIs across areas such as greenhouse gas emissions, energy and water usage, waste, employee wellbeing and related attributes. The KPIs are chosen because they can be measured and independently verified.

The key distinction is verification. The full BRSR tells the story. BRSR Core provides the checked numbers that support it. One is broad and descriptive. The other is narrow and assured.

Who Must Comply and When

The requirement applies on a phased, size based schedule.

SEBI structured BRSR Core assurance to reach the largest listed companies first, then extend downward. Based on the SEBI framework, the phasing works in this order:

• From FY 2025-26: the top 250 listed companies by market capitalisation fall within the BRSR Core assurance requirement.
• From FY 2026-27: the requirement extends to the top 1000 listed companies.

This staged approach gives smaller listed entities more time to build their data systems. It does not remove the eventual obligation. A company in the top 1000 today should treat FY 2026-27 as a planning horizon, not a distant possibility.

Requirements can change. Check the current SEBI circulars and any updates before finalising your reporting approach.

The Value Chain Effect Reaches Unlisted Businesses

This is the part many suppliers miss. BRSR Core does not stop at the listed company.

The SEBI framework addresses ESG disclosures for the value chain. From FY 2025-26, the top 250 listed companies are expected to report BRSR Core data for their value chain partners on a specified basis. To do that, they need the underlying data from those partners.

The practical consequence is direct. A listed company subject to the requirement will ask its suppliers, including unlisted businesses, for BRSR Core KPIs. If you supply a large listed customer, you may receive a data request even though you are not listed and file no BRSR yourself.

This does not mean every supplier faces identical obligations. The scope depends on your customer’s requirements and how they define their value chain. The safer assumption is that if you serve large listed clients, ESG data requests are coming, and preparing early is easier than responding under pressure.

Why Third Party Assurance Matters

Assurance exists to make ESG data trustworthy. Self declared figures carry limited weight with investors, regulators and large buyers.

Independent assurance means an external body reviews the BRSR Core KPIs and checks that they are measured and reported reliably. This turns a claimed number into a verified one.

The benefit is credibility. Investors making decisions on ESG grounds want data they can rely on. Regulators want disclosures that hold up to scrutiny. Value chain customers want supplier data they can consolidate into their own assured reports. Third party assurance for BRSR supports all three at once.

Importantly, assurance does not correct weak underlying data. It checks what exists. If the source data is incomplete or poorly documented, assurance will surface that rather than fix it. Good data systems come first; assurance confirms them.

Common Mistakes Companies Make

A few errors repeat across organisations preparing for BRSR Core reporting.

• Treating it as a last minute reporting task. BRSR Core depends on data collected across a full financial year. Starting near the deadline leaves gaps that cannot be filled retrospectively.
• Confusing the full BRSR with the Core. Assuming the whole report needs assurance, or that none of it does, leads to misdirected effort.
• Ignoring the value chain request. Suppliers who wait for a formal demand often scramble when a major customer asks for data with a short turnaround.
• Weak data governance. ESG data sits across operations, HR, facilities and procurement. Without clear ownership, the numbers are hard to assemble and harder to assure.
• Poor documentation. Assurance relies on evidence. Figures without a traceable basis are difficult to verify.

The pattern is consistent. Most difficulties trace back to data readiness and timing, not to the assurance itself.

How to Prepare for BRSR Core Assurance

Preparation follows a logical sequence. Working through it early reduces pressure at reporting time.

• Confirm your applicability. Check where your company sits in the market capitalisation ranking and which reporting year applies to you.
• Map the KPIs. Identify the specific BRSR Core indicators relevant to your operations.
• Assign data ownership. Give each KPI a clear owner across the relevant functions.
• Build the evidence trail. Document how each figure is measured, sourced and calculated.
• Assess your value chain. Identify which partners you need data from, or which customers may request data from you.
• Engage an assurance provider. Select an independent body to review the BRSR Core KPIs against the framework.

The earlier you begin, the more time you have to correct data gaps before they reach an assurance review.

How IRQS Supports BRSR Core Reporting

IRQS (Indian Register Quality Systems) offers services relevant to this requirement. On its validation and verification page, IRQS lists verification and assurance of corporate sustainability reports and BRSR (Business Responsibility and Sustainability Reports) among its services.

This matters for a practical reason. BRSR Core rarely sits in isolation. It connects to wider sustainability work such as greenhouse gas verification, corporate emissions reporting, and product carbon footprint assessment. IRQS lists services across several of these areas, which allows a company to approach BRSR Core assurance alongside its broader ESG activity rather than through separate providers.

For businesses drawn into the value chain requirement, this breadth is useful. A supplier preparing ESG data for a listed customer often needs help understanding which KPIs apply and how to document them. This does not mean every organisation needs the full range of services. The relevant point is that BRSR Core assurance can be handled within a wider sustainability relationship where that suits your operation.

Frequently Asked Questions

What is BRSR Core reporting?

BRSR Core is a defined subset of ESG key performance indicators within the Business Responsibility and Sustainability Report that SEBI requires listed companies to have independently assured. It was introduced through a SEBI circular dated 12 July 2023 and focuses on measurable, verifiable data rather than narrative disclosure.

Is assurance required for the entire BRSR?

No. Assurance applies to the BRSR Core, a defined subset of ESG KPIs. The wider BRSR contains many descriptive disclosures that fall outside the mandatory assurance requirement. It would be inaccurate to treat the whole report as requiring assurance.

Which companies must comply with BRSR Core?

The requirement is phased by market capitalisation. Based on the SEBI framework, the top 250 listed companies fall within the assurance requirement from FY 2025-26, and the top 1000 from FY 2026-27. Requirements can change, so check current SEBI circulars.

Does BRSR Core affect unlisted companies?

It can. From FY 2025-26, the top 250 listed companies are expected to report BRSR Core data for their value chain. To do so, they request data from suppliers, including unlisted businesses. If you supply a large listed customer, you may receive such a request.

What is the difference between BRSR and BRSR Core?

The full BRSR is a broad, largely narrative sustainability report. BRSR Core is a narrow set of measurable KPIs within it that require independent assurance. The full report tells the story; the Core provides the assured numbers.

Why is third party assurance important for BRSR?

Independent assurance makes ESG data credible to investors, regulators and value chain customers. It checks that KPIs are measured and reported reliably. It does not correct weak underlying data, so good data systems must come first.

How long does BRSR Core assurance take?

Timelines depend on the number of KPIs, the quality of your data, and the readiness of your documentation. Companies with strong data governance move faster. Engaging an assurance provider early allows a realistic timeline to be set for your reporting year.

Prepare Before the Requirement Reaches You

BRSR Core reporting changes ESG disclosure from a story you tell into data you can prove. The companies that manage it well are the ones that build their data systems early, assign clear ownership, and document their figures throughout the year rather than at the deadline.

Organisations preparing for BRSR Core reporting, or suppliers responding to value chain data requests, can contact IRQS to discuss their reporting year, applicable KPIs, and the appropriate assurance scope. A short conversation about your obligations and your data readiness is usually the fastest way to plan the right approach before the requirement becomes urgent.