Professional accountants carrying out audit engagements in line with ISAs (UK) and other public interest assurance engagements in the UK:

• should apply the FRC's definition of PIE;
• are expected to comply with the requirements relating to PIEs which are set out in the FRC’s Ethical Standard for Auditors; and
• do NOT need to comply with Part 4A of the ICAEW Code.

In the Glossary of Terms, the FRC defines PIEs in the following way:

“Public Interest Entities. These are:

• (a) An issuer whose transferable securities are admitted to trading on a UK regulated market16;
• (b) A credit institution within the meaning of Article 4(1)(1) of Regulation (EU) No 575/2013 of the European Parliament and of the Council17, which is a CRR firm within the meaning of Article 4(1)(2A) of that Regulation;
• (c) A person who would be an insurance undertaking as defined in Article 2(1) of Council Directive 91/674/EEC of 19 December 1991 of the European Parliament and of the Council on the annual accounts and consolidated accounts of insurance undertaking as that Article had effect immediately before exit day, were the United Kingdom a Member State.

No other entities have been specifically designated in law in the UK as 'public interest entities'.”

However, the definition of PIE introduced by IESBA into section R400.17 of the 2025 Code will still be relevant for professional accountants practising outside the UK; and professional accountants undertaking non-public interest assurance engagements in the UK, in accordance with Part 4B of the Code.