The 15% cap

No specific figure is mentioned for unlisted. Auditors have to satisfy themselves that there is no undue influence ie a threat to objectivity and independence arising from fees. The 15% applies to public interest clients (such as listed).

The ACCA rule book states 290.217: Where an audit client is a public interest entity and, for two consecutive years, the total fees from the client and its related entities .......represent more than 15% of the total fees received by the firm expressing the opinion on the financial statements of the client, the firm shall disclose to those charged with governance of the audit client the fact that the total of such fees represents more than 15% of the total fees received by the firm, and discuss which of the safeguards below it will apply to reduce the threat to an acceptable level, and apply the selected safeguard.... So disclosure is to the audit committee/board, not the shareholders. The audit committee has a supervisory role and its independence would be compromised by having the chief internal auditor on it. They might have to criticise IA.