## External Auditor's Responsibility and Objectives under SA 610

### Core Principle: Sole Responsibility

The external auditor bears sole responsibility for the audit opinion. This responsibility is not reduced even when:

The work of the internal audit function (IAF) is used, or
Internal auditors provide direct assistance on the engagement.

### Why Internal Auditors Cannot Share Responsibility

Although internal auditors may perform procedures similar to external audit procedures, they are not independent of the entity — a fundamental requirement under SA 200. The external auditor remains the sole accountable party.

### Objectives of the External Auditor (where entity has an IAF)

Where the external auditor expects to use IAF work or direct assistance, there are three distinct objectives:

Objective	Description
(a) Determine usability	Decide whether IAF work or direct assistance can be used, and if so, in which areas and to what extent
(b) Adequacy check	Determine whether the IAF work actually used is adequate for the audit
(c) Direction and supervision	Appropriately direct, supervise, and review internal auditors providing direct assistance

### Key Distinction

Using IAF work = relying on procedures IAF already performed (modify nature/timing/extent of external audit procedures)
Direct assistance = internal auditors perform procedures under the external auditor's direction and supervision

Worked example

### Example 1

Example – Sole Responsibility in Practice:

XYZ Ltd.'s external auditor relies on the IAF's inventory count observations and their testing of controls over payroll. The IAF's work reduces the extent of external audit testing. At the conclusion, the external auditor issues an unmodified opinion.

Question: Has the external auditor's responsibility for the audit opinion been reduced?

Answer: No. The external auditor retains sole responsibility for the opinion under SA 610. The use of IAF work only affects the extent of external audit procedures, not who owns the opinion.

### Example 2

Example – Objective Classification:

The external auditor of ABC Corp decides to:

Rely on IAF's testing of IT controls (already performed)
Ask two internal auditors to accompany and assist in branch visit observations

Classify each against SA 610 objectives:

Relying on IT controls testing → Objective (a) and (b): determine usability and assess adequacy
Branch observation assistance → Objective (a) and (c): determine usability and then direct/supervise/review the internal auditors

⚠️ Common exam mistakes

Believing the external auditor's responsibility is proportionally reduced when IAF does more work — it is never reduced regardless of how much IAF work is used.
Treating 'using IAF work' and 'direct assistance' as the same concept — using IAF work means relying on procedures the IAF already performed; direct assistance means IAF performs procedures under external auditor's instructions.
Forgetting that the independence requirement under SA 200 is the reason internal auditors cannot share audit responsibility.

Bare-Act text Responsibility of the External Auditor · SA 610 – Using the Work of Internal Auditors · click to expand

The external auditor has sole responsibility for the audit opinion expressed, and that responsibility is not reduced by the external auditor's use of the work of the internal audit function or internal auditors to provide direct assistance on the engagement.

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External Auditor's Sole Responsibility and Objectives

Worked example

⚠️ Common exam mistakes