Using Specialists: Expertise Does Not Transfer Accountability

A specialist can explain a technical matter that an audit team cannot resolve on its own. The auditor still needs to decide whether that work answers the audit question, uses relevant evidence and supports the conclusion being drawn.

Consider an original fictional cold-storage business. A refrigeration unit has suffered repeated failures. Management's maintenance contractor says it can keep operating. The financial-statement audit team needs technical evidence relevant to a machinery estimate and considers engaging an engineering specialist. An equipment condition report may help, but its purpose and limits matter as much as the specialist's credentials.

Define the question before selecting the expert

Separate three questions. What is the machine's present condition? What operating assumptions underpin the engineer's assessment? What do those findings mean for the accounting estimate under the applicable reporting framework?

An engineer may be well qualified to assess mechanical deterioration without being engaged to determine an accounting value. A maintenance inspection aimed at keeping a unit running may address a different objective from an assessment prepared for the audit. The team should identify the expertise needed, the relevant date and the evidence gap before commissioning a report.

In this case, a useful brief would identify the unit, the assessment date, the intended technical questions, available operating records and significant limitations. It would also distinguish the specialist's technical contribution from the auditor's responsibilities.

Identify whose expert produced the work

A contractor's report used by management is not automatically work performed by an auditor's expert. ISA 620 addresses the auditor's use of expertise outside accounting or auditing; management's expert falls within the audit-evidence considerations in ISA 500. Accounting or auditing specialists on an engagement involve a different category again.

This distinction changes how the team scopes and evaluates the work. It is not a ranking of professional titles. An existing report can be informative while remaining insufficient for the particular audit purpose.

Look beyond a credential

Evaluate whether the person has relevant technical experience, the capacity to complete the work and the ability to approach it objectively. In the fictional case, experience with similar refrigeration systems matters more than a generic engineering title.

Suppose the proposed specialist also designs replacement units for the same business. That relationship needs examination; it is neither proof of bias nor a reason to assume there is no threat. The team needs facts about interests, relationships and the work to be performed, followed by an appropriate response under applicable requirements.

Access also matters. A capable engineer may still be unable to support a useful assessment if the team provides only a summary of repairs while omitting operating logs or restricting inspection of the affected unit.

Evaluate the work, not only the report cover

Compare the actual output with the agreed purpose. Does it identify the correct unit and date? Are the methods and significant assumptions appropriate? Is important source information complete and accurate? Do the findings agree with other evidence, or does a contradiction remain unexplained?

For example, the report might assume normal operating temperatures while logs indicate repeated excursions. The auditor should understand and resolve the difference rather than select whichever document supports the preferred result. Further specialist work or other audit procedures may be needed.

An estimate's eventual outcome can differ from an earlier assessment without proving the earlier work was negligent. The question is whether the evidence and reasoning supported the conclusion at the relevant time.

Keep the conclusion with its accountable owner

Under ISA 620, using an auditor's expert does not reduce the auditor's responsibility for the audit opinion. Technical findings can contribute evidence; they do not authorize the auditor to outsource the overall audit judgment.

Try the exercise on a technical topic you know. Write the audit question, the expert's narrower question and one limitation that could prevent the work from being adequate. Explain what further evidence would close that gap.

The case is fictional and educational. The primary reference is ISA 620 in the IAASB 2026 Handbook. That edition incorporates amendments with their own effective dates, including changes for periods beginning on or after 15 December 2026. Determine the standards and ethical requirements applicable to the actual engagement; publication of a handbook alone does not make every incorporated amendment immediately applicable. Internal audit engagements require consideration of their own applicable standards.

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