25. For banks, the ECL estimate is likely to be subject to significant estimation uncertainty, complexity and subjectivity [ISA 540 (Revised), Auditing Accounting Estimates and Related Disclosures, paragraph A67(a).], and thus at a higher ROMM due to fraud or error, including a greater risk of management bias. If a bank's external auditor were to fail to exercise professional scepticism when auditing the ECL estimate, a material misstatement in the financial statements could go undetected.