Auditor Interview Questions

External auditors are independent of the client and provide a formal audit opinion on whether the financial statements are true and fair. Internal auditors work for the organisation and evaluate internal controls, operational efficiency, and compliance with policies. Both require professional qualification but serve different purposes; external audit is statutory for larger companies, whilst internal audit is preventative and strategic. Many auditors transition between the two; internal audit roles are often considered less client-facing and more strategic.

Materiality is the threshold above which an error would influence a user's economic decisions about the organisation. It's typically expressed as a percentage of profit before tax or revenue. If a misstatement is below materiality, an auditor won't necessarily require the client to correct it because it doesn't significantly distort the financial picture. Setting materiality is a key audit judgement; it's lower for companies where accuracy is critical (banks, charities) and higher for large profitable companies.

Auditors use sampling techniques to select a representative subset of transactions. They might use systematic sampling (every 10th item), random sampling, or risk-based sampling (focusing on larger items or unusual transactions). Tools like ACL and IDEA automate this selection. The auditor then tests the selected sample in detail, extrapolates the error rate across the full population, and determines whether any errors found are material. This approach is efficient and statistically valid if the sample is selected correctly.

An audit finding is any issue identified during the audit: a misstatement in the accounts, a control weakness, a non-compliance with regulation, or a process inefficiency. Not all findings are equally serious; a clerical error in a non-material transaction is low-risk, whereas a systemic control breakdown or fraud indicator is critical. Auditors classify findings by severity and communicate them to management and audit committees. Material findings may require the auditor to qualify the audit opinion (add warnings) or issue an adverse opinion (accounts are not reliable).

An external audit of a mid-size company typically spans 4–8 weeks of on-site fieldwork, depending on complexity, system maturity, and quality of the client's records. Planning and preliminary work add 1–2 weeks; reporting and finalisation add another 1–2 weeks. Total timeline from planning to sign-off is often 8–12 weeks. Larger organisations or those with poor controls may require longer audits. The client's readiness (having records organised and staff available) significantly affects the timeline.

You'll use Excel extensively for analysis and working papers. Audit firms typically provide audit management software (Arbutus, TeamMate) to manage files, document findings, and track sign-offs. For data analysis and sampling, you'll learn ACL, IDEA, or Alteryx to extract and test large datasets directly from the client's system. You'll also work with client accounting systems (SAP, NetSuite, Sage) and use Tableau for analytical visualisation. Excel VBA and SQL skills are valuable for automating repetitive tests and extracting data efficiently.