ISSA 5000 does not automatically govern every sustainability assurance engagement in the United States. US reporting teams instead face a mix of state requirements, AICPA attestation standards, international engagements, and voluntary investor or customer commitments.
The practical question is not simply “Does ISSA 5000 apply in the US?” It is which assurance requirement applies to the company, which standards the regulator or engaging party accepts, and whether a group-level engagement uses a standard adopted in another jurisdiction.
The US position in 2026
As of August 10, 2026, US adoption work remains in progress. The AICPA Auditing Standards Board issued exposure drafts in 2026 covering common attestation concepts and engagements to report on sustainability information. The comment period closed June 30, and the project remained under discussion rather than a final US standard.
At the federal level, the Securities and Exchange Commission proposed rescinding its 2024 climate disclosure rules in May 2026. That proposal does not remove state requirements, contractual reporting, international obligations, or voluntary assurance programs.
California therefore remains central. CARB’s March 2026 workshop materials proposed several acceptable standards for future Scope 1 and Scope 2 assurance under SB 253, including AICPA standards, AA1000AS, ISO 14064-3, and IAASB standards. The staff concepts expressly included ISSA 5000 once effective in December 2026. Because rulemaking was still developing, companies should verify the final regulation rather than treating workshop slides as a binding list.
Our US climate disclosure guide explains the wider federal and California landscape.
Why ISSA 5000 readiness still matters
An American company can encounter ISSA 5000 even without a universal US mandate. A multinational parent may request information for an ISSA 5000 group engagement. A company may choose an international standard for voluntary assurance. A lender or customer may expect a recognized global baseline. California may also permit ISSA 5000 for a regulated engagement once its rules are final.
The standard can cover sustainability information prepared under any suitable criteria. It is broader than greenhouse gas verification alone and addresses qualitative disclosures, estimates, forward-looking information, value-chain information, and the reporting process that produces them.
Build one evidence base for multiple assurance pathways
US teams should avoid creating a separate evidence package for each possible standard. Build a controlled reporting foundation that can be mapped to the final engagement requirements.
Priorities include:
- A complete population of entities, facilities, emission sources, and relevant Scope 3 categories.
- Version-controlled source data, emission factors, calculations, and restatements.
- Documented criteria for organizational boundaries, materiality, estimates, and exclusions.
- Evidence that review controls actually operated, including preparer, reviewer, date, exceptions, and resolution.
- A reconciliation between the assured information and every public location where the same metric appears.
For California reporting, preserve the revenue and “doing business” assessment, reporting-period decisions, and evidence used to prepare the submitted inventory. Those scoping records may be just as important as the emissions workbook.
Decisions to make before engaging a provider
Confirm the accepted assurance standard, provider eligibility, level of assurance, covered metrics, and reporting deadline. If a group uses ISSA 5000 while a US entity uses AICPA or ISO standards, agree on component instructions and whether the group practitioner can use the component provider’s work.
Management should also understand the difference between a readiness assessment and an assurance conclusion. A readiness review can identify gaps, but only an eligible independent practitioner can issue the assurance report.
Carbon Impact’s ISSA 5000 solution helps reporting teams manage the data lineage, evidence, controls, and review status behind either a domestic or international engagement.
This article reflects information available on August 10, 2026. California and federal rulemaking may change; confirm current requirements. This is general information, not assurance or legal advice.
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