What is ISSB / IFRS S1 & S2?

Investor-grade disclosures • UK-ready implementation

The ISSB standardsIFRS S1 (general sustainability-related disclosures) and IFRS S2 (climate-related disclosures)—define a global baseline for reporting material sustainability and climate information that can affect enterprise value. They are designed to be consistent, comparable, and decision-useful for investors.

Related: UK SDRESG StrategyNet Zero & Carbon

IFRS S1 & IFRS S2 in 90 seconds

ISSB uses a familiar disclosure structure (governance, strategy, risk management, metrics & targets). The key difference is the enterprise value lens: disclose sustainability and climate issues that could reasonably affect financial performance over time.

IFRS S1

General sustainability-related disclosures: material risks/opportunities, how they’re governed, managed, and measured.

IFRS S2

Climate disclosures: transition & physical risks, resilience, scenario considerations, emissions metrics and targets.

Why it matters

Investors want comparable, decision-useful sustainability information. ISSB reduces fragmentation across reporting regimes.

Prepare fast

Treat it as a controls + evidence programme: data ownership, calculation notes, controls, approvals, evidence pack.

What “ISSB-ready” looks like in practice

Organisations that succeed typically build four things: disclosure architecture, governance, data controls, and an evidence trail.

Area Minimum standard RSustain UK outputs
Governance Accountability, escalation paths, board oversight, disclosure approvals. Governance map, RACI, approval workflow, policy templates.
Strategy linkage Material issues linked to business model, risks, financial planning. Materiality summary, risk mapping, KPI/target logic, narrative library.
Metrics & targets Defined metrics, boundaries, calculation methods, target definitions. Metric dictionary, calculation notes, target protocol, disclosures index.
Data controls & evidence Source systems, data owners, validation checks, version control. Controls library, evidence pack, change log, audit-traceability design.

Note: RSustain UK provides advisory & implementation support and does not provide statutory or third-party assurance.

Implementation checklist (fast and safe)

Use this to move from “policy intent” to an operational disclosure system.

1) Scope & materiality

Define material topics (enterprise value lens), boundaries, and reporting perimeter.

2) Disclosure architecture

Create disclosure index + crosswalks; define required narratives and metrics.

3) Data ownership & controls

Assign owners, define data sources, add validation checks and change control.

4) Evidence pack

Build calculation notes, evidence files, approvals, and traceability.

Pro tip: If you want ISSB-ready Net Zero disclosures, start with a defensible Scope 1–3 baseline and method notes. See Net Zero & Carbon Management.

ISSB / IFRS S1 & S2 FAQs

Are IFRS S1/S2 only for listed companies?

They’re designed for capital markets, but private companies often adopt them to satisfy lenders, investors, and customers.

Is IFRS S2 basically TCFD?

IFRS S2 uses a similar structure (governance, strategy, risk management, metrics/targets). The focus is investor-grade, enterprise value relevant climate information with strong controls and comparability.

What is the biggest failure point?

Weak data controls and missing evidence trails. The fix is a data dictionary, calculation notes, owner sign-offs, and an evidence pack aligned to disclosures.

Make your disclosures investor-grade

Build ISSB-aligned disclosure architecture, controls, and evidence packs—so sustainability reporting stands up to scrutiny.

Book a call with RSustain UK

Advisory & implementation support only. No statutory or third-party assurance.