Ciferi Blog

ISA & IFRS Standards — Explained

Plain-language guides to audit standards, methodology, and practical insights for practitioners.


Showing 40 of 40 guides

General Principles & Responsibilities

ISA 200–265 · 8 guides

ISA 200 — Overall Objectives of the Independent Auditor

Reasonable assurance, the audit risk model, professional skepticism, and how ISA 200 connects to every other auditing standard.

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ISA 210 — Agreeing the Terms of Audit Engagements

Preconditions for an audit, what the engagement letter must contain, recurring audits, and when to decline or withdraw.

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ISA 220 (Revised) — Quality Management for an Audit

The engagement partner's responsibilities, the shift from quality control to quality management, resources, direction and supervision, and the engagement quality review.

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ISA 230 — Audit Documentation

The experienced auditor test, form and extent of documentation, timely preparation, file assembly, and modifications after the report date.

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ISA 240 — The Auditor's Responsibilities Relating to Fraud

The fraud triangle, management override, revenue recognition presumption, required procedures, and the revised ISA 240 (2025).

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ISA 250 (Revised) — Consideration of Laws and Regulations

Two categories of laws, the auditor's responsibilities for each, NOCLAR framework, reporting obligations, and non-compliance procedures.

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ISA 260 (Revised) — Communication with Those Charged with Governance

TCWG identification, required communications, planned scope and timing, significant findings, independence, and two-way dialogue.

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ISA 265 — Communicating Deficiencies in Internal Control

Internal control deficiencies, significant deficiencies, the management letter, who to communicate to, and what to include.

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Risk Assessment & Response

ISA 300–450 · 6 guides

ISA 300 — Planning an Audit of Financial Statements

The overall audit strategy vs. the audit plan, preliminary engagement activities, the iterative nature of planning, and documentation requirements.

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ISA 315 (Revised 2019) — Identifying and Assessing the Risks of Material Misstatement

The risk assessment process, five components of internal control, inherent risk factors, the spectrum of inherent risk, significant risks, and IT considerations.

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ISA 320 — Materiality in Planning and Performing an Audit

How materiality is determined, common benchmarks and percentages, performance materiality, specific materiality, revision during the audit, and qualitative considerations.

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ISA 330 — The Auditor's Responses to Assessed Risks

Overall responses vs. assertion-level responses, tests of controls vs. substantive procedures, dual-purpose testing, interim testing, and the stand-back requirement.

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ISA 402 — Audit Considerations Relating to an Entity Using a Service Organisation

User auditor responsibilities, Type 1 vs. Type 2 reports (ISAE 3402), complementary user entity controls, subservice organisations, and the carve-out vs. inclusive method.

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ISA 450 — Evaluation of Misstatements Identified During the Audit

Accumulating misstatements, the clearly trivial threshold, factual vs. judgmental vs. projected misstatements, and evaluating uncorrected misstatements.

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Audit Evidence

ISA 500–580 · 11 guides

ISA 500 — Audit Evidence

Sufficient and appropriate evidence, the seven types of audit procedures, the reliability hierarchy, and using information from external sources.

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ISA 501 — Audit Evidence: Specific Considerations for Selected Items

Inventory attendance and test counts, litigation and claims procedures, legal confirmation letters, and segment information.

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ISA 505 — External Confirmations

Positive vs. negative confirmations, blank confirmations, maintaining control, handling non-responses and exceptions, and management refusal.

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ISA 510 — Initial Audit Engagements: Opening Balances

Predecessor auditor work, procedures when prior year was unaudited, accounting policy consistency, and reporting implications for first-year engagements.

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ISA 520 — Analytical Procedures

How analytical procedures work as substantive procedures and as overall review at audit completion, developing expectations, setting thresholds, and investigating fluctuations.

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ISA 530 — Audit Sampling

Statistical vs. non-statistical sampling, sample design and size, tolerable misstatement and deviation rate, selection methods, projecting misstatements, and evaluating results.

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ISA 540 (Revised) — Auditing Accounting Estimates and Related Disclosures

Estimation uncertainty, the spectrum of inherent risk, the three inherent risk factors, management bias, the auditor's testing approaches, and enhanced documentation requirements.

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ISA 550 — Related Parties

How to identify related parties and transactions, assess associated risks, audit significant transactions outside the normal course of business, evaluate arm's length assertions, and deal with dominant influence.

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ISA 560 — Subsequent Events

The three time periods for subsequent events, adjusting vs. non-adjusting events, the auditor's active and passive duties, dual dating, and what happens when facts emerge after the financial statements are issued.

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ISA 570 (Revised) — Going Concern

The auditor's going concern responsibilities, indicators of doubt, management's assessment, material uncertainty (MURGC), reporting implications, and the upcoming 2024 revision.

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ISA 580 — Written Representations

Why written representations are required, what they must cover, who signs them, when management refuses or representations are unreliable, and the consequences for the audit opinion.

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Using Work of Others

ISA 600–620 · 3 guides

ISA 600 (Revised) — Audits of Group Financial Statements

The risk-based approach to group audits, the revised component definition, aggregation risk, component materiality, two-way communication with component auditors, and documentation requirements.

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ISA 610 (Revised 2013) — Using the Work of Internal Auditors

When and how the external auditor can use the work of internal audit, evaluating objectivity and competence, direct assistance, prohibited activities, and jurisdictional restrictions.

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ISA 620 — Using the Work of an Auditor's Expert

Auditor's experts vs. management's experts, evaluating competence and objectivity, the agreement, evaluating adequacy of the expert's work, and when to reference the expert in the report.

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Audit Conclusions & Reporting

ISA 700–810 · 9 guides

ISA 700 (Revised) — Forming an Opinion and Reporting on Financial Statements

How the auditor forms an opinion, the prescribed report structure, fair presentation vs. compliance frameworks, and the interaction with ISA 701, 705, 706, and 570.

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ISA 701 — Communicating Key Audit Matters

What Key Audit Matters are, the funnel determination process, what good KAM descriptions look like, the relationship with modified opinions and EOM paragraphs, and common KAM categories.

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ISA 705 (Revised) — Modifications to the Opinion in the Auditor's Report

The three types of modified opinions — qualified, adverse, and disclaimer — the material vs. pervasive distinction, scope limitations, and how modifications affect the report structure.

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ISA 706 (Revised) — Emphasis of Matter and Other Matter Paragraphs

The difference between EOM and OM paragraphs, when each is required, their relationship with KAM and modified opinions, and practical examples from European jurisdictions.

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ISA 710 — Comparative Information: Corresponding Figures and Comparative Financial Statements

Corresponding figures vs. comparative financial statements, the auditor's responsibilities for each, prior-period issues, predecessor auditor situations, and the 'ghost effect' of unresolved prior-period modifications.

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ISA 720 (Revised) — The Auditor's Responsibilities Relating to Other Information

The auditor's responsibilities for other information in annual reports, material inconsistency procedures, the 'knowledge obtained in the audit' comparison, reporting requirements, and European positive reporting obligations.

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ISA 800 (Revised) — Audits of Special Purpose Financial Statements

Special considerations for auditing financial statements prepared under special purpose frameworks — tax basis, regulatory, contractual — the mandatory EOM paragraph, going concern adaptations, and European regulatory reporting.

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ISA 805 (Revised) — Audits of Single Financial Statements and Specific Elements

Special considerations for auditing single financial statements or specific elements, materiality at the element level, interrelationships, and the critical restriction when an adverse or disclaimer opinion exists on the complete set.

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ISA 810 (Revised) — Engagements to Report on Summary Financial Statements

Reporting on summary financial statements derived from audited accounts, the same-auditor requirement, applied criteria, the binary opinion structure, and interactions with modified opinions on the complete set.

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ISAE Standards

ISAE 3000+ · 3 guides

ISAE 3000 (Revised) — Assurance Engagements Other Than Audits or Reviews

The framework for non-audit assurance engagements, reasonable and limited assurance levels, the ISAE 3000 ecosystem including ISAE 3402 and ISSA 5000, CSRD sustainability assurance, and European implementations.

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ISAE 3402 — Assurance Reports on Controls at a Service Organization

Type 1 and Type 2 reports on service organisation controls, carve-out vs inclusive methods for subservice organisations, complementary user entity controls, and the user auditor's perspective.

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ISAE 3410 — Assurance Engagements on Greenhouse Gas Statements

Assurance on greenhouse gas statements, emission quantification across Scope 1/2/3, scientific vs estimation uncertainty, site visits, the transition to ISSA 5000, and European jurisdiction implementations.

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