The Chief Sustainability Officer (CSO) role has evolved from a reputational function into a strategic compliance and risk management position. As the EU's Corporate Sustainability Reporting Directive (CSRD) raises the bar for sustainability disclosure, and as investors and customers demand greater accountability, the CSO’s responsibilities have expanded significantly.

This article explores what it means to be an effective CSO in 2026 — the competencies required, the organizational challenges to navigate, and the tools and frameworks that matter most.

From voluntary to mandatory: how the CSO role has changed

A decade ago, sustainability was largely a voluntary, communications-driven function. CSOs focused on ESG reports, stakeholder engagement, and corporate responsibility narratives. Today, the role is fundamentally different:

• CSRD makes sustainability statements legally mandated and subject to external assurance
• Scope 3 emissions data requires coordination across procurement, finance, and supply chain
• Double materiality assessments require engagement from the board, finance, legal, and HR
• Climate risk must be integrated with financial risk management

CSOs who have not yet made this transition — from voluntary reporter to compliance owner — risk being overtaken by events.

The skills that matter most for CSOs in 2026

Data and reporting literacy

Understanding GHG accounting methodology, ESRS disclosure requirements, and the data quality standards needed for limited assurance is now a baseline requirement. CSOs don’t need to be engineers, but they need to be able to evaluate methodology claims, identify data gaps, and hold vendors and internal teams accountable for data quality.

Cross-functional influence

CSRD reporting requires contributions from finance, HR, legal, procurement, and operations. CSOs who can only operate within their own function will struggle. The most effective CSOs build sustainability into existing business processes rather than creating parallel sustainability systems.

Regulatory fluency

The regulatory landscape is moving fast: Omnibus has changed CSRD scope and timelines, CSDDD is being simplified, and new frameworks like VSME and ISSB are gaining traction. CSOs need to understand the current state of regulation and anticipate what’s coming.

Financial and investor communication

Increasingly, CSOs are presenting to boards and investors. Being able to translate sustainability performance into financial risk language — and to connect ESG strategy to the company’s business model — is becoming essential.

The CSO’s relationship with the CFO

One of the most important relationships for a CSO is with the CFO. CSRD brings sustainability disclosures into the annual report and requires financial-quality data controls. CSOs who treat the CFO as a partner rather than an obstacle tend to be far more effective at building credible, auditable sustainability programs. See also our guide on why finance teams shouldn’t try to solve sustainability with spreadsheets.

What the best CSOs are doing differently

• Treating CSRD preparation as a capability-building exercise, not just a compliance deadline
• Starting the double materiality assessment early and involving the board
• Building supplier engagement programs for Scope 3 data before they’re required
• Choosing sustainability platforms that integrate with finance and ERP systems
• Engaging auditors before reporting begins, not after

How Coolset supports CSOs

Coolset provides CSOs with the platform to run CSRD compliance end-to-end: from double materiality assessment through data collection, carbon accounting, and audit-ready sustainability statements. The platform is designed for sustainability teams without large IT departments and integrates with finance processes. Book a demo to see how it works.