ESG Assurance & Verification

ESG assurance provides independent verification of ESG disclosures, enhancing credibility and stakeholder trust.

Types of Assurance

Limited Assurance — Review procedures, negative assurance ("nothing came to our attention")
Reasonable Assurance — Audit procedures, positive assurance ("in our opinion, fairly stated")

Most ESG assurance is currently limited assurance. Regulations increasingly require reasonable assurance for key metrics.

Assurance Standards

ISAE 3000 — International Standard on Assurance Engagements (general purpose)
ISAE 3410 — Assurance on greenhouse gas statements
AA1000AS — AccountAbility Assurance Standard (stakeholder-focused)

What Gets Assured?

Commonly Assured:

• GHG emissions (Scope 1, 2, sometimes 3)
• Energy consumption
• Water usage
• Waste generation
• Health and safety statistics

Increasingly Assured:

• Climate-related financial disclosures (TCFD)
• Sustainability reports (full or selected disclosures)
• Supply chain data

Assurance Process

1. Planning

Define scope (which disclosures), level (limited or reasonable), and criteria (reporting standards).

2. Risk Assessment

Identify areas of material misstatement risk based on data complexity and controls.

3. Evidence Gathering

Inquiry — Interview data owners
Inspection — Review documentation and systems
Observation — Visit facilities
Recalculation — Verify calculations
Analytical Procedures — Compare trends

4. Reporting

Issue assurance statement describing scope, procedures, findings, and conclusion.

Choosing an Assurance Provider

Big Four Accounting Firms — PwC, Deloitte, EY, KPMG (financial audit expertise)
Specialist ESG Firms — ERM, DNV, SGS (technical ESG expertise)
Industry Certifiers — Sector-specific verification bodies

Regulatory Requirements

EU CSRD — Reasonable assurance required (phased from 2028)
California Climate Disclosure — Third-party assurance required
SEC Climate Rule (proposed) — Attestation for Scope 1 & 2 emissions

From ESG Library

• ESG Reporting Made Simple (IFRS/SASB) — Assurance considerations for IFRS S1/S2

View all books →

Key Resources

• IAASB International Standard on Sustainability Assurance (ISSA 5000)
• AccountAbility AA1000 Assurance Standard

Part of ESG Hub | Curated by Ascent Partners Foundation