The International Standard on Sustainability Assurance (UK) 5000 provides UK companies, investors and assurance with a ‘consistent, internationally aligned assurance standards for voluntary use in sustainability assurance engagements’, the Financial Reporting Council (FRC) said.

ISSA (UK) 5000 is the UK version of the global standard for sustainability assurance, developed by the International Auditing and Assurance Standards Board (IAASB), but is not mandatory for auditors to use.

It will be effective for assurance engagements on sustainability information reported for periods beginning on or after 15 December 2026.