ESG Data Assurance
Independent assurance of non-financial data under ISAE 3000 (Revised) and ISAE 3410 (GHG statements). We verify the accuracy, completeness, and reliability of your reported ESG metrics — from BRSR Core KPIs to GHG emissions, water, waste, safety, and governance indicators.
Data Categories Under Assurance
GHG Emissions
Scope 1 & 2 emissions data, emission factors, calculation methodologies, organisational boundaries, and year-on-year trends. ISAE 3410 specific standard for GHG statements.
Water & Effluent
Water withdrawal, consumption, discharge, and recycling data. Source classification, quality parameters, and ZLD compliance metrics.
Waste & Circularity
Hazardous and non-hazardous waste generation, disposal pathways, diversion rates, and EPR compliance data.
Energy
Energy consumption, renewable/non-renewable split, intensity metrics, and PAT scheme compliance data.
Social KPIs
LTIFR, fatality data, gender diversity metrics, wage data, sexual harassment complaints, training hours, and employee wellbeing indicators.
Governance
Board diversity, ESG committee effectiveness, anti-corruption metrics, stakeholder engagement data, and policy compliance indicators.
Limited vs Reasonable Assurance
Limited Assurance
Negative assurance: "Nothing has come to our attention that causes us to believe the data is materially misstated." Primarily inquiry and analytical procedures. SEBI's initial mandate for BRSR Core. Suitable for companies in their first years of assurance.
Reasonable Assurance
Positive assurance: "The data is fairly stated in all material respects." Extensive testing, reperformance, and evidence examination. Higher-grade opinion. SEBI is phasing in reasonable assurance for select BRSR Core KPIs.
Six-Step Assurance Process
Scoping & Independence
Engagement-specific conflict-of-interest review. Scope definition, fee proposal, engagement letter. Independence verified before any work begins.
Planning & Risk Assessment
Assessment plan, evidence requirements, materiality thresholds, team assignment. Tailored to your sector and data maturity.
Evidence Collection
Document review, data verification, calculation reperformance, evidence quality audit. Source data examination, not just reported figures.
Testing & Interviews
Management interviews, analytical procedures, site-level checks, stakeholder engagement review. Substantive and compliance testing.
Draft Findings
Preliminary findings shared, management responses documented, factual accuracy confirmed. No surprises in the final report.
Assurance Opinion
Formal assurance statement, management letter with recommendations, board presentation. Delivered in formats ready for regulatory filing.
Note: RSustain provides independent assurance where engagement-specific independence requirements are met. For BRSR Core assurance specifically, the final assurance provider is appointed directly by your company in accordance with SEBI requirements.
Complete Assurance Ecosystem
AA1000 Assurance
AccountAbility Principles-based assurance. Type 1 (principles) and Type 2 (principles + data). Licensed provider across 11 SASB sectors.
Learn more →BRSR Core Assurance Sprint
12-week advisory programme to prepare your BRSR Core data, controls, and evidence for third-party scrutiny.
Learn more →Assurance Services Overview
Compare all assurance offerings and find the right engagement for your company's needs and maturity level.
View all services →RSustain Assurance Readiness Tools
Pre-Assurance Validator
92 validation rules mapped to ISAE 3000. Check your BRSR Core data for completeness, accuracy, and consistency before the assurance provider arrives.
Launch tool →GHG Assurance Workbench
Verification evidence manager for GHG inventories. Organise evidence against ISO 14064 requirements for smooth GHG assurance engagements.
Launch tool →ScopeTracer
GHG emissions mapping with documented calculation methodology — essential for ISAE 3410 GHG statement assurance.
Launch tool →ESG Data Assurance FAQ
Is BRSR Core assurance mandatory?
Yes, for companies within SEBI's phased mandate. BRSR Core assurance is mandatory for the top 150 listed companies from FY 2023-24, expanding to top 500 (FY 2025-26) and top 1,000 (FY 2026-27) by market capitalisation. The assurance must be conducted by an independent practitioner under recognised assurance standards (ISAE 3000, ISAE 3410, or equivalent). The assurance opinion is published alongside the annual report.
Who can provide BRSR Core assurance?
SEBI has specified that BRSR Core assurance may be provided by (1) audit firms (CA firms), (2) companies providing assurance services, and (3) other bodies with relevant sustainability/ESG assurance competence. The assurance provider must be independent of the reporting entity. SEBI does not currently require a specific accreditation, but competence in ISAE 3000 (Revised) and relevant subject matter expertise is expected. RSustain provides both assurance readiness advisory and independent assurance where independence requirements are met.
What is ISAE 3000 and why does it matter?
ISAE 3000 (Revised) — International Standard on Assurance Engagements — is the global standard for assurance of non-financial information. It provides the framework for both limited and reasonable assurance engagements covering sustainability data. ISAE 3410 is the specific standard for GHG statement assurance. Using recognised standards ensures the assurance opinion is credible and accepted by regulators, investors, and rating agencies.
How should we prepare for ESG assurance?
Preparation should start 3-6 months before the assurance engagement. Key steps: (1) establish data collection processes with documented methodologies, (2) maintain source records and evidence trails for all reported KPIs, (3) implement internal review and sign-off procedures, (4) run our Pre-Assurance Validator to check for common errors, and (5) prepare a management representation letter. Companies engaging in assurance for the first time should consider our BRSR Core Assurance Sprint programme.
What is the difference between ESG assurance and financial audit?
Financial audits verify financial statements under ISA standards with well-established accounting frameworks (Ind AS). ESG assurance verifies non-financial data under ISAE 3000/3410 — but ESG data often lacks the standardised measurement frameworks of financial accounting. ESG data comes from diverse sources (EHS systems, HR databases, utility meters, manual registers), uses varied calculation methodologies, and has weaker internal controls. This makes ESG assurance more complex and emphasises the importance of documented methodologies and evidence trails.
Get Your ESG Data Independently Verified
Book a scoping call to discuss assurance scope, timeline, and engagement structure.
Book Scoping Call →