Exploring the Relationship between IFRS & ISA: Key Insights
Audit and accounting firms, legal auditors, and accountants who apply international auditing standards (ISA & SOCPA) and manage comprehensive audit files often ask: how do International Financial Reporting Standards (IFRS) interact with International Standards on Auditing (ISA)? This article explains the relationship between IFRS & ISA, showing how the standards complement each other, where responsibilities diverge, and practical implications for sampling in auditing, auditor independence, documenting evidence and findings, files and working papers, and audit planning and closing. It is part of a content cluster that supports our pillar guide — see the reference pillar article below for a full IFRS overview.
Why this topic matters for audit firms and legal auditors
IFRS defines how an entity recognizes, measures and presents financial information; ISA defines how auditors obtain and evaluate audit evidence about that information. For firms that must comply with ISA & SOCPA and audit IFRS-based financial statements, understanding the relationship between IFRS & ISA is essential to:
- Design appropriate audit procedures that target IFRS-specific risks (e.g., revenue recognition, impairment of goodwill).
- Maintain auditor independence while exercising professional skepticism on management judgments under IFRS.
- Ensure audit files and working papers show a clear trail between accounting estimates, IFRS requirements, and audit evidence.
- Improve audit quality and control by aligning audit planning and closing stages with IFRS-driven judgmental areas.
Knowing the interaction prevents misinterpretation — auditors do not re-write IFRS, but they must verify that financial statements prepared under IFRS are free from material misstatement.
Core concept: How IFRS and ISA relate (definitions, components, examples)
Definitions
IFRS: A set of accounting standards issued by the IASB that prescribes recognition, measurement, presentation and disclosure of transactions and events in financial statements.
ISA: Standards issued by the IAASB setting out the objectives and minimum procedures for auditors to follow when conducting an audit of financial statements.
Complementary roles
Think of IFRS as the “what” (what must be reported) and ISA as the “how” (how to audit what is reported). For example:
- IFRS requires an entity to test goodwill for impairment when indicators exist (IAS 36). ISA requires auditors to evaluate management’s impairment testing assumptions and to design sampling in auditing of supporting data.
- IFRS mandates disclosure of accounting policies and judgments; ISA requires the auditor to document evidence and findings supporting their conclusion on whether those disclosures are adequate.
Where responsibilities diverge
Auditors do not prepare financial statements or set accounting policy. Their responsibility is to express an opinion on whether financial statements give a true and fair view in accordance with IFRS. When management applies subjective judgments, auditors must test and challenge those judgments without replacing management’s role.
Example workflow (practical)
- Audit Planning: Identify IFRS areas with high judgment (e.g., expected credit losses, ECL under IFRS 9).
- Risk Assessment: Map IFRS requirements to audit assertions (existence, valuation, presentation, disclosure).
- Design Tests: Use sampling in auditing for population testing; design procedures for testing accounting estimates.
- Fieldwork: Document evidence and findings in files and working papers; maintain auditor independence throughout procedures.
- Closing: Evaluate whether audit evidence supports an auditor’s opinion on IFRS compliance and prepare final documentation for quality control review.
For reference on general auditing frameworks and interpretation, auditors should be familiar with the key international auditing standards that frame many ISA applications.
Practical use cases and scenarios
This section covers recurring situations where the relationship between IFRS & ISA directly affects audit design and execution.
1. Revenue recognition under IFRS 15
Scenario: A client has bundled contracts and complex variable consideration. IFRS 15 requires identification of performance obligations and estimation of variable consideration.
Audit approach: During audit planning, identify revenue-related risks; design tests for revenue recognition using both substantive procedures and controls testing. Use sampling in auditing to test a mix of contract types; document judgments and testing in files and working papers. Check that disclosures meet IFRS 15 requirements.
2. Expected credit losses (ECL) under IFRS 9
Scenario: A bank uses models to calculate ECL. These are model-driven accounting estimates with significant management judgment.
Audit approach: Evaluate model governance and controls, perform sensitivity analysis, validate key inputs, and document evidence and findings related to model performance. Maintain clear lines about auditor independence when engaging specialists.
3. Impairment of non-financial assets
Scenario: Management triggers impairment testing due to market changes.
Audit approach: Assess reasonableness of CGUs, discount rates, and future cash flow forecasts. Use specialists prudently and ensure their work is referenced and appropriately documented in audit files.
Impact on audit decisions, performance, and outcomes
Understanding the interplay between IFRS and ISA affects several firm outcomes:
- Quality of opinion: Clear linkage between IFRS requirements and audit evidence improves the defensibility of audit opinions.
- Efficiency: Early mapping of IFRS-heavy risk areas to audit procedures reduces rework at closing and lowers time spent per engagement by an estimated 10–20% on complex clients.
- Audit Quality and Control: Structured documentation and strong sampling strategies reduce likelihood of quality review comments and restatements.
- Client relationships: Transparent communication about required disclosures and audit requirements builds trust and reduces surprises at reporting time.
For operational framing, ensure your firm’s quality control mechanisms reference the audit quality under ISA guidance so that reviewers and engagement partners can align evidence with IFRS requirements consistently.
Common mistakes and how to avoid them
Mistake 1: Treating auditing and accounting tasks as interchangeable
Fix: Document roles explicitly in audit planning. Use checklists that separate management judgments under IFRS from audit tests under ISA.
Mistake 2: Inadequate documentation of evidence and findings
Fix: Adopt a standardized files and working papers structure that cross-references IFRS requirements to audit procedures, sample selection, and conclusions.
Mistake 3: Poor sampling design
Fix: Apply statistical and judgmental sampling methods appropriately. Record sample population, selection method, confidence levels, and projected misstatements in the working papers.
Mistake 4: Over-reliance on management experts without verification
Fix: Where management uses internal specialists for valuations, verify their independence, competence and document corroborative procedures. Keep audit independence under continuous review.
Practical, actionable tips and checklists
Below are step-by-step actions you can implement immediately on engagements that involve IFRS-specific complexities.
Audit planning checklist (IFRS-focused)
- Map IFRS standards likely to affect the client (e.g., IFRS 9, IFRS 15, IAS 36).
- Identify high-risk areas and estimate materiality thresholds by financial statement area.
- Plan sampling in auditing: choose sample size based on expected deviation rate and desired confidence level.
- Allocate specialists and document scope; define deliverables and deadlines.
- Plan documentation standards for files and working papers: executive summary, risk matrix, evidence index.
Fieldwork & documentation tips
- Use standardized templates that link IFRS disclosure requirements to the audit procedures performed and the evidence obtained.
- For accounting estimates, retain copies of management’s calculations, model inputs, and sensitivity analyses in working papers.
- Keep continuity in files: reference previous year’s working papers where relevant and justify changes.
- Log independence considerations and confirmations for all partners and specialists on the engagement.
Closing & reporting checklist
- Confirm that unresolved issues relating to IFRS application are escalated and cleared.
- Ensure financial statement disclosures are complete and agree to schedules in working papers.
- Prepare a clear audit conclusion document linking evidence to IFRS compliance and auditor opinion.
- Conduct a quality review focused on whether audit documentation supports significant judgments and the final opinion.
For detailed methodology on audit procedures, your teams should refer to the foundations of ISA standards and internal manuals to keep technical application consistent across engagements.
KPIs / success metrics
Use these KPIs to track how well your firm translates IFRS-ISA alignment into measurable performance improvements:
- Percentage of audits with fully completed files and working papers at closing (target: 95%+).
- Average time spent in audit closing per engagement (days) — target decrease of 10–20% year-over-year.
- Number of review comments related to IFRS misapplication or documentation (target: reduce by 50% within 12 months).
- Rate of significant adjustments required after fieldwork (target: < 2% of engagements).
- Quality-control pass rate on final review (target: 98% compliant with ISA-based quality checks).
FAQ
Q: If a company applies IFRS, do we as auditors need additional procedures?
A: Yes. IFRS can introduce complex estimates and presentation requirements. Your audit plan should identify IFRS-specific risks and include tailored procedures (e.g., model validation, disclosure checklists). Use targeted sampling in auditing and document the rationale for selected procedures in your files and working papers.
Q: How should we document judgments when management uses significant estimates under IFRS?
A: Record a clear trail: management’s estimate, source data, assumptions, sensitivity analysis, auditor’s procedures, specialists’ reports (if any), and the final conclusion. A summary page linking the evidence to the final opinion is invaluable during quality reviews.
Q: Can auditor independence be affected when we use specialists to audit IFRS estimates?
A: It can. Independence must be assessed for each specialist engaged. Document their qualifications, relationship to the client, and the scope of their work. Avoid using firm staff who may have served in a management role for the client in the prior period.
Q: What is a common sampling pitfall in IFRS-related audits?
A: Using a sample size too small for areas with high judgment or heterogenous populations. Mitigate by stratifying the population and increasing sample sizes for high-value or high-risk strata, and document the statistical assumptions used.
Next steps — actionable plan & auditsheets
To put this guidance into practice on your next IFRS-engagement, follow this three-step plan:
- Run an IFRS risk-mapping session during planning to identify top 3 judgmental areas and map ISA procedures to each.
- Implement standardized working paper templates that link IFRS requirements to audit evidence and sampling rationale.
- Use a final quality checklist that references audit quality controls and documents independence confirmations.
If you want a tool that helps operationalize these steps — from risk mapping to files and working papers management — consider trying auditsheets to standardize documentation and improve audit quality across engagements.
Reference pillar article
This article is part of a content cluster supporting our pillar piece: The Ultimate Guide: What are International Financial Reporting Standards (IFRS)? – an overview. Read the pillar to deepen your understanding of IFRS fundamentals and return here for practical ISA-aligned audit application.