ISA Standards

ISQM 1

Quality Management for Firms that Perform Audits or Reviews of Financial Statements, or Other Assurance or Related Services Engagements

Requires every firm to design, implement and operate a risk-based system of quality management over its audit, review, assurance and related services practice.

ISQM 2

Engagement Quality Reviews

Sets out who may perform an engagement quality review, what the reviewer must evaluate, and what must be documented before the engagement report is dated.

ISA 200

Overall Objectives of the Independent Auditor and the Conduct of an Audit in Accordance with International Standards on Auditing

States what an audit is for, the auditor's overall objectives, and the ethical, sceptical and evidential foundations every other ISA builds on.

ISA 210

Agreeing the Terms of Audit Engagements

Requires the auditor to establish that the preconditions for an audit exist and to agree the terms of the engagement in writing before starting.

ISA 220 (Revised)

Quality Management for an Audit of Financial Statements

Places responsibility for managing and achieving quality on each audit engagement squarely on the engagement partner, within the firm's ISQM 1 system.

ISA 230

Audit Documentation

Sets what the audit file must contain, the experienced-auditor test, and the rules for assembling and changing the file after the report is dated.

ISA 240

The Auditor's Responsibilities Relating to Fraud in an Audit of Financial Statements

Defines the auditor's role in detecting material misstatement due to fraud, the fraud triangle, the required procedures and the presumptions on revenue and management override.

ISA 250 (Revised)

Consideration of Laws and Regulations in an Audit of Financial Statements

Distinguishes laws with a direct effect on the financial statements from other laws, and sets the auditor's procedures and reporting when non-compliance is identified or suspected.

ISA 260 (Revised)

Communication with Those Charged with Governance

Requires two-way communication with those charged with governance on the auditor's responsibilities, the planned scope and timing, significant findings and independence.

ISA 265

Communicating Deficiencies in Internal Control to Those Charged with Governance and Management

Requires the auditor to communicate, in writing and on a timely basis, the significant deficiencies in internal control identified during the audit.

ISA 300

Planning an Audit of Financial Statements

Requires the auditor to plan the audit so it is performed effectively: preliminary engagement activities, an overall audit strategy and a detailed audit plan.

ISA 315 (Revised 2019)

Identifying and Assessing the Risks of Material Misstatement

Sets the risk assessment procedures, the understanding of the entity, its environment, the applicable framework and its system of internal control, and how risks are identified and assessed at two levels.

ISA 320

Materiality in Planning and Performing an Audit

Requires the auditor to set materiality for the financial statements as a whole, performance materiality, and specific materiality where needed, and to revise them as the audit progresses.

ISA 330

The Auditor's Responses to Assessed Risks

Requires overall responses at the financial statement level and further procedures at the assertion level, tests of controls and substantive procedures, whose nature, timing and extent respond to the assessed risks.

ISA 402

Audit Considerations Relating to an Entity Using a Service Organization

Explains how the user auditor obtains an understanding of, and evidence about, controls at an outsourced service organisation, including the use of Type 1 and Type 2 reports.

ISA 450

Evaluation of Misstatements Identified during the Audit

Requires the auditor to accumulate misstatements, ask management to correct them, and evaluate the effect of uncorrected misstatements, individually and in aggregate, on the financial statements and the opinion.

ISA 500 (Revised)

Audit Evidence

Explains what constitutes audit evidence and how the auditor designs and performs procedures to obtain sufficient appropriate evidence, including evaluating information used as evidence.

ISA 501

Audit Evidence: Specific Considerations for Selected Items

Sets specific evidence requirements for inventory (attendance at the physical count), litigation and claims (inquiry and legal letters), and segment information.

ISA 505

External Confirmations

Governs the design and control of confirmation requests to third parties, the evaluation of responses, non-responses and exceptions, and management refusals.

ISA 510

Initial Audit Engagements: Opening Balances

Sets the evidence the auditor obtains on opening balances and the consistency of accounting policies when the prior period was unaudited or audited by a predecessor.

ISA 520

Analytical Procedures

Governs analytical procedures used as substantive evidence and the analytical review required near the end of the audit to support the overall conclusion.

ISA 530

Audit Sampling

Sets how the auditor designs, selects, performs and evaluates an audit sample, including projecting misstatements and considering sampling and non-sampling risk.

ISA 540 (Revised)

Auditing Accounting Estimates and Related Disclosures

Sets a risk-based approach to auditing estimates: understand how they are made, assess inherent risk from complexity, subjectivity and uncertainty, and test the method, assumptions and data or develop an auditor's range.

ISA 550

Related Parties

Requires the auditor to understand the entity's related party relationships and transactions, remain alert to undisclosed ones, and evaluate whether they are properly accounted for and disclosed.

ISA 560

Subsequent Events

Sets the auditor's procedures for events between the reporting date and the report date, and the actions when facts become known after the report is dated or the statements are issued.

ISA 570 (Revised 2024)

Going Concern

Requires the auditor to evaluate management's going concern assessment, conclude on material uncertainty and the appropriateness of the basis, and report explicitly on going concern.

ISA 580

Written Representations

Requires written representations from management on its responsibilities and on specific matters, and sets what the auditor does when they are unreliable or refused.

ISA 600 (Revised)

Special Considerations: Audits of Group Financial Statements (Including the Work of Component Auditors)

Sets the group auditor's responsibilities for planning, directing and supervising a group audit, involving component auditors, and evaluating their work before signing the group opinion.

ISA 610 (Revised 2013)

Using the Work of Internal Auditors

Sets when and how the external auditor may use the work of the internal audit function, or use internal auditors to provide direct assistance, without reducing the external auditor's responsibility.

ISA 620

Using the Work of an Auditor's Expert

Sets when the auditor needs an expert in a field other than accounting or auditing, how the expert's competence and objectivity are evaluated, and how the expert's work is agreed and evaluated as evidence.

ISA 700 (Revised)

Forming an Opinion and Reporting on Financial Statements

Sets how the auditor forms the opinion and the required form and content of the auditor's report, section by section, for an unmodified opinion.

ISA 701

Communicating Key Audit Matters in the Independent Auditor's Report

Requires the auditor of a listed entity to select and describe the matters of most significance in the audit, and sets how each is described and when one may be withheld.

ISA 705 (Revised)

Modifications to the Opinion in the Independent Auditor's Report

Sets the three modified opinions (qualified, adverse, disclaimer), when each applies based on the nature of the matter and its pervasiveness, and how the report is worded.

ISA 706 (Revised)

Emphasis of Matter Paragraphs and Other Matter Paragraphs in the Independent Auditor's Report

Sets when and how the auditor adds a paragraph drawing attention to a matter disclosed in the financial statements, or to a matter outside them, without modifying the opinion.

ISA 710

Comparative Information: Corresponding Figures and Comparative Financial Statements

Sets the auditor's procedures on comparative information and how the report deals with it under the two approaches, corresponding figures and comparative financial statements.

ISA 720 (Revised)

The Auditor's Responsibilities Relating to Other Information

Requires the auditor to read the other information in the annual report, consider whether it is materially inconsistent with the financial statements or the auditor's knowledge, and report on it in a dedicated section.

ISA 800 (Revised)

Special Considerations: Audits of Financial Statements Prepared in Accordance with Special Purpose Frameworks

Adapts the ISAs to an audit of financial statements prepared for specific users under a special purpose framework, including the alert that restricts their use.

ISA 805 (Revised)

Special Considerations: Audits of Single Financial Statements and Specific Elements, Accounts or Items of a Financial Statement

Adapts the ISAs to an audit of one statement or one element, including how the opinion relates to any audit of the complete set and when a separate report is permitted.

ISA 810 (Revised)

Engagements to Report on Summary Financial Statements

Sets when the auditor may report on summary financial statements derived from audited statements, the procedures required, and the form of the report and its opinion.

ISRE 2400 (Revised)

Engagements to Review Historical Financial Statements

Governs a limited assurance review of financial statements by a practitioner who is not the entity's auditor: inquiry and analytical procedures leading to a negative-form conclusion.

ISRE 2410

Review of Interim Financial Information Performed by the Independent Auditor of the Entity

Governs the review of an entity's interim financial information by its own auditor, using the auditor's knowledge from the annual audit to reach a limited assurance conclusion.

ISAE 3000 (Revised)

Assurance Engagements Other than Audits or Reviews of Historical Financial Information

The umbrella standard for every assurance engagement on subject matter other than historical financial statements: the five elements, reasonable versus limited assurance, and attestation versus direct engagements.

ISAE 3400

The Examination of Prospective Financial Information

Governs engagements to examine forecasts and projections: assessing the assumptions, checking preparation and presentation, and reporting with negative assurance on assumptions and an opinion on preparation.

ISAE 3402

Assurance Reports on Controls at a Service Organization

Governs the service auditor's engagement to report on the description, design and operating effectiveness of controls at a service organisation for use by user entities and their auditors.

ISAE 3410

Assurance Engagements on Greenhouse Gas Statements

Governs reasonable or limited assurance on an entity's greenhouse gas statement: understanding emissions and the quantification process, testing the data and methods, and reporting.

ISAE 3420

Assurance Engagements to Report on the Compilation of Pro Forma Financial Information Included in a Prospectus

Governs reasonable assurance on whether pro forma financial information in a prospectus has been properly compiled on the basis stated, without assuring the underlying figures or the transaction.

ISRS 4400 (Revised)

Agreed-Upon Procedures Engagements

Governs engagements where the practitioner performs procedures agreed with the engaging party and reports factual findings, giving no assurance and expressing no opinion.

ISRS 4410 (Revised)

Compilation Engagements

Governs engagements where the practitioner uses accounting expertise to prepare and present financial information for management, with no assurance and a report that says so.

ISSA 5000

General Requirements for Sustainability Assurance Engagements

The IAASB's overarching standard for reasonable or limited assurance on sustainability information reported under any framework, effective for periods beginning on or after 15 December 2026.