Singapore has set a clear destination for climate assurance: external limited assurance over Scope 1 and Scope 2 greenhouse gas emissions. The reporting requirements start first, giving companies time to improve their data and controls before assurance becomes mandatory.
ISSA 5000 is highly relevant to that preparation, but companies should not state that Singapore already mandates it. The IAASB listed Singapore’s adoption as in progress as of May 2026, while ACRA’s current requirements specify the assurance level, timing, and eligible provider categories rather than naming ISSA 5000 as the only standard.
Singapore’s current assurance timetable
ACRA’s July 2026 requirements page says external limited assurance over Scope 1 and Scope 2 emissions begins:
- From FY2029 for listed companies.
- From FY2032 for large non-listed companies in scope.
Eligible providers will be audit firms registered with ACRA or testing, inspection, and certification firms accredited by the Singapore Accreditation Council.
The reporting timetable begins earlier. All listed companies report Scope 1 and Scope 2 emissions from FY2025, with other ISSB-based climate disclosures phased by index status and market capitalization. Large non-listed companies meeting the revenue and asset thresholds generally enter from FY2030. Our updated Singapore climate reporting roadmap sets out those dates.
The gap between reporting and assurance is an implementation window. Companies can use their early reporting cycles to remove manual work, clarify methodologies, and produce evidence consistently.
Where ISSA 5000 fits
ISSA 5000 is a global standard for limited and reasonable assurance over sustainability information. It is framework-neutral and profession-agnostic, subject to quality management, ethics, and independence conditions.
For a Singapore company, its role will depend on the final local adoption and implementing rules, the provider selected, and any group reporting instructions. A parent company based in a jurisdiction that has adopted ISSA 5000 may also bring a Singapore component into an ISSA 5000 group engagement before the domestic mandate begins.
Use the reporting years to create assurance evidence
For Scope 1 and Scope 2, start with completeness. Maintain an approved register of entities, facilities, leased assets, meters, fuels, refrigerants, and purchased-energy accounts. Reconcile that register to finance, property, procurement, and operational systems.
Then make every calculation repeatable:
- Preserve the original source record and extraction context.
- Record units, conversions, estimation methods, and data substitutions.
- Version emission factors and global warming potential values.
- Document the consolidation approach and organizational boundary.
- Retain evidence of preparer and reviewer controls, including resolved exceptions.
Scope 2 needs particular discipline. Document whether location-based and market-based totals are reported, how contractual instruments are assessed, and how renewable energy claims connect to underlying records.
Although the first mandate covers emissions, ISSB-based climate disclosures also include governance, strategy, risk management, and metrics and targets. Evidence for those narratives should be retained now because future assurance scope can expand and group engagements may already cover them.
Prepare for provider selection
Singapore’s dual provider pathway means companies should evaluate more than brand and price. Ask which assurance and ethics standards the provider will use, how independence is assessed, whether specialists or component practitioners will be involved, and how the provider’s quality management system meets the applicable requirements.
Agree on the assured metrics, level of assurance, reporting boundary, evidence access, site work, and issue-resolution timetable. A readiness review is useful, but keep advisory work distinct from the independent assurance conclusion.
Carbon Impact’s ISSA 5000 assurance-readiness workflow helps reporting teams centralize boundaries, source data, calculations, evidence, reviews, and group reporting requests ahead of fieldwork.
This article reflects information available on August 10, 2026. Singapore’s adoption and implementing standards may evolve. This is general information, not assurance or legal advice.
Sources
See how Carbon Impact supports ISSA 5000 reporting — from data collection to disclosure.