Advanced Audit and Assurance (International) · Evidence and testing considerations

Using Others' Work and Specialist Evidence in Audit

Updated 11 October 2026 · Fact-checked

Using others' work means the auditor relies on internal auditors (ISA 610), an auditor's expert (ISA 620) or component auditors (ISA 600) for audit evidence. You must assess their competence, objectivity and the quality of their work, direct and review it, and keep sole responsibility for the opinion.

Understand Using Others' Work and Specialist Evidence (ISA 610, 620, 600)

You cannot always do every piece of audit work yourself. A client may have an internal audit team. A valuation may need a specialist. A group may have subsidiaries audited by other firms. The standards let you use this work, but only on conditions.

ISA 610 (Revised 2013) covers internal auditors. You can use their work as evidence, or use them to give direct assistance. First decide whether the function is likely to be relevant. Then judge its objectivity (organisational status, reporting lines), competence and whether it applies a systematic and disciplined approach, including quality control. Direct assistance must not be used where there are significant threats to objectivity. It must also not be used for work involving significant judgement, or for work related to higher assessed risks of material misstatement where more than limited judgement is needed. You must still direct, supervise and review.

ISA 620 covers an auditor's expert: an individual or organisation with expertise in a field other than accounting or auditing, whose work you use. Examples are property valuers, actuaries and IT specialists. You assess the expert's competence, capabilities and objectivity. You must understand their field, agree scope, roles and communication, and evaluate whether their work is adequate. This means checking the relevance and reasonableness of findings, assumptions, methods and source data. If the work is inadequate, you agree further work or do other procedures. You do not refer to the expert in an unmodified auditor's report unless law or regulation requires it. In a modified report, ISA 620 allows a reference only where it is relevant to understanding the modification, and the wording must make clear that your responsibility is not reduced.

ISA 600 covers group audits. The group engagement partner is responsible for the group opinion. Under ISA 600 (Revised), the report must not refer to component auditors unless law or regulation requires it. If it does, the report must state that the reference does not reduce the group engagement partner's responsibility. ISA 600 (Revised) is risk-based. It focuses on the risks of material misstatement at group level and on the work needed on components to address them, not just on how significant a component is. You identify and assess risks at group level, decide which components need work, and set the nature, timing and extent of involvement. You must understand the component auditor, including ethical requirements, independence and competence, communicate clearly, and evaluate their work. Do not treat this as a mechanical checklist. Apply it to the scenario's facts.

The key principle in all three: you may use the work, but you remain responsible for the opinion. Your reliance must be justified by evaluating the other party and their work.

Key rules to remember

Core principle: Reliance = evaluate competence + objectivity + quality of work, then direct and review; Applies to internal auditors, experts and component auditors. Responsibility for the opinion stays with the auditor.
ISA 610 assessment factors: Objectivity + competence + systematic and disciplined approach; Use these to decide whether to use internal audit work. Also consider the nature and extent of the work and the risk.
ISA 610 limit on use: Greater judgement or higher risk → less reliance; Reliance is lower where significant judgement or significant risks are involved. Direct assistance is prohibited where objectivity is threatened.
ISA 620 evaluation: Evaluate relevance and reasonableness of findings, assumptions and methods, and the source data; Check consistency with other evidence and the use of source data.
ISA 600 responsibility: Group engagement partner remains responsible for the group opinion; The group auditor's report does not refer to component auditors unless law or regulation requires it.
Reporting reference: No reference to the expert, internal audit or component auditor unless law or regulation requires it.; Law or regulation may require a reference. The modified-report allowance applies to an ISA 620 auditor's expert only, not to internal auditors or component auditors. ISA 620 allows a reference to the expert in a modified report only where it is relevant to understanding the modification, with wording that makes clear your responsibility is not reduced. For component auditors, ISA 600 (Revised) allows a reference only where law or regulation requires it, and the report must then state that it does not reduce the group engagement partner's responsibility.

How to solve Using Others' Work and Specialist Evidence (ISA 610, 620, 600) questions

Use this method for any question on relying on internal audit, experts or component auditors. Tie each point to the scenario.

1Identify which party is being used and which ISA applies: internal audit (610), expert (620) or component auditor (600).
2Decide whether the work is relevant to the audit and which risk or balance it relates to.
3Assess the party: competence, objectivity and, where relevant, quality control or systematic approach. Use scenario facts such as reporting lines, qualifications, relationships and fee dependence.
4Judge the significance of the area. High risk or significant judgement means less reliance and more auditor involvement.
5State what you will do: agree scope and timing, communicate requirements, direct, supervise and review, and re-perform some work.
6Evaluate the work: reasonableness of assumptions, methods and source data, and consistency with other evidence.
7Conclude on whether the evidence is sufficient and appropriate, and what you do if it is not.
8Confirm that responsibility for the opinion remains with you, and consider the effect on the auditor's report.

Quickest way: Three-test shortcut

When to use it: Use this when time is short and you need a quick, credible structure for a written answer.

Name the standard and the party in one line.
Test 1: competence. Test 2: objectivity. Test 3: quality of work.
Add one scenario fact against each test.
Show how you will control the work: scope, direction, review.
Close with: responsibility for the opinion stays with the auditor.

Common mistakes in Using Others' Work and Specialist Evidence (ISA 610, 620, 600)

Saying the auditor can transfer responsibility to the expert or component auditor.
Students think using specialists means sharing the blame.
Fix: State that the auditor keeps sole responsibility for the opinion. The group engagement partner is responsible for the group opinion.
Listing the ISA criteria without applying them to the scenario.
Students memorise lists and skip the case facts.
Fix: Pair each criterion with a fact, such as the head of internal audit reporting to the finance director, which weakens objectivity.
Treating internal auditors as external evidence of the same quality.
Students overlook that internal audit is part of the entity.
Fix: Explain that its work is internal evidence, and that objectivity and risk limit reliance. High-risk areas need more of your own work.
Forgetting to evaluate the expert's work and just accepting the valuation.
Students assume specialist means correct.
Fix: Evaluate assumptions, methods and source data, and compare with other evidence. Consider further procedures if inadequate.
Mentioning the expert or component auditor in an unmodified auditor's report.
Students think transparency is always better.
Fix: State that an unmodified report does not refer to them unless law or regulation requires it. For an auditor's expert, ISA 620 allows a reference in a modified report only where it is relevant to understanding the modification, and the wording must make clear that your responsibility is not reduced. For component auditors, ISA 600 (Revised) says the report must not refer to them unless law or regulation requires it, and then the report must state that the reference does not reduce the group engagement partner's responsibility. An unnecessary reference could imply divided responsibility.
Treating all components in a group as needing the same work.
Students apply a one-size approach.
Fix: Use a risk-based approach. Decide the work and involvement by the risks of material misstatement at group level and what each component contributes to them, not by size alone. Also consider the component auditor's competence.

Worked examples

Example 1

You audit Zeta Co. The internal audit team reports to the finance director and performed inventory count checks at depots. You wish to use this work to reduce your own testing. Discuss whether you can rely on it.

Show the solution

The standard is ISA 610. Inventory is relevant, and the work could provide evidence.
Objectivity: the team reports to the finance director, whose area it checks. This is a threat to objectivity. Ask whether the audit committee has any oversight of the team.
Competence: check qualifications, experience and training of the team.
Systematic approach: check for documented procedures, supervision and review of working papers.
Risk: inventory is usually significant, with judgement over valuation. This reduces the extent of reliance.
Procedures: evaluate the work by re-performing a sample of counts and comparing results, and attend some counts yourself.
Conclusion: any reliance is limited, and responsibility for the opinion remains with you.

Answer: Limited reliance is possible. The reporting line to the finance director weakens objectivity, and inventory is a significant area. Evaluate competence and the quality of the work, re-perform a sample, and do enough own work. You remain responsible.

Example 2

The auditor of Delta Co plans to use a property valuer as an auditor's expert for the valuation of investment property. The valuer is a long-standing adviser to Delta's directors. Explain the matters to consider and what the auditor should do.

Show the solution

The standard is ISA 620, because the valuer's field is outside accounting and auditing and the auditor proposes to use the valuer as an auditor's expert.
Objectivity: ISA 620 requires the auditor to evaluate whether the expert is objective. A valuer who is a long-standing adviser to the directors is closely tied to management. This is a significant threat to objectivity, through familiarity and self-interest. Consider whether safeguards can reduce the threat to an acceptable level. If they cannot, do not use this valuer as the auditor's expert. Either engage an independent valuer, or treat the existing valuation as the work of a management's expert and evaluate it under ISA 500, with extra professional scepticism.
Competence: check qualifications, membership of a professional body, and experience with similar property.
Understand the field: gain enough knowledge to agree scope and evaluate the work.
Agree terms: scope, roles, nature and timing of communication, and confidentiality.
Evaluate the work: the reasonableness of assumptions such as yields and rental growth, the methods, and the source data such as lease details. Compare with market evidence.
If inadequate, agree further work or perform other procedures. Do not refer to the expert in an unmodified report.

Answer: The auditor should assess competence and objectivity. The valuer's close tie to the directors is a significant threat to objectivity. If safeguards cannot reduce it to an acceptable level, the auditor should not use this valuer as an auditor's expert. The auditor should either engage an independent valuer, or treat the existing valuation as a management's expert's work and evaluate it under ISA 500 with extra scepticism. In either case, the auditor should evaluate assumptions, methods and data, and take further steps if the work is inadequate.

Exam tips

Always name the ISA and the party, then apply competence, objectivity and quality to the scenario facts.
Use the professional skills marks: show scepticism by questioning the reporting line, relationship or inconsistency you spot.
Say that responsibility for the opinion stays with the auditor. Examiners expect this in most answers on this topic.
Distinguish an auditor's expert (620) from a management's expert, and use of internal audit work from direct assistance.
For groups, link the work to risk: focus on the risks of material misstatement at group level and the work needed on components, not just component size.

Practice questions from Evidence and testing considerations

Using Others' Work and Specialist Evidence (ISA 610, 620, 600) in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

ACCA Applied SkillsUsing the Work of Internal Auditors

Using Others' Work and Specialist Evidence (ISA 610, 620, 600): frequently asked questions

When can an external auditor rely on internal audit?

When the function is relevant to the audit and you assess it as objective, competent and applying a systematic and disciplined approach. Even then, you evaluate the work and limit reliance in high-risk or high-judgement areas.

What is the difference between an auditor's expert and a management's expert?

An auditor's expert is engaged by the auditor and falls under ISA 620. A management's expert is engaged by the entity, and the auditor treats their work as evidence under ISA 500, evaluating their competence, objectivity and the work.

Does the group auditor have to refer to component auditors in the report?

No. Under ISA 600 (Revised), the report must not refer to component auditors unless law or regulation requires it. If a reference is required, the report must state that it does not reduce the group engagement partner's responsibility for the group opinion.

Can internal auditors give direct assistance to the external auditor?

Only if law does not prohibit it, and if threats to objectivity are not significant and competence is adequate. The external auditor must direct, supervise and review the work. Direct assistance must not be used for work involving significant judgement, or for higher assessed risks of material misstatement where more than limited judgement is needed.