Skip to main content
Welcome to Deloitte

If we have selected the wrong experience for you, please change it above.

From sample to full-population examination

What Artificial Intelligence changes for the third line

Internal audit samples activity to judge firm-wide control, leaving concentrated risks unseen.  AI enables testing entire populations, shifting assurance from inference to evidence. Audit data analytics make planning and evidence gathering data‑driven and support continuous auditing. Tools and models must be validated, and outputs must be traceable. Auditors must apply professional scepticism to preserve independence.

A role that was already changing

Internal audit has been shifting from box-ticking to forward-looking, risk‑based assurance. Audit committees now expect insight on emerging and strategic risks, not just control exceptions. Capacity was the barrier. Experienced auditors spent much of their time on data gathering, routine tests and documentation. AI reduces the mechanical workload and lets those auditors focus on judgement and investigation. 

What broader coverage actually enables

Testing whole populations does more than speed up work. Where data quality allows, the audit can examine every relevant record. Audit opinions can then state which items were reviewed and which exceptions were found. That is a stronger and more defensible form of assurance. Wider coverage also makes rare, concealed, or dispersed issues easier to detect. It gives the audit a firmer basis for prioritising work and for challenging the business. 

Examples from current industry practice 

Below are practical examples of how audit teams use analytics and AI. In each case, the tool extends what the audit can examine and how work is documented. The auditor retains responsibility for judgement and opinion.

Audit teams use analytics and AI to test entire populations of payments, journal entries or trades against defined rules, replacing sample‑based testing where the data supports it. This increases coverage and strengthens audit conclusions. It requires that the underlying data meet sufficient quality standards.

Risk analytics combine operational, financial, and behavioural data to map current risk. Audit plans follow the evidence, not last year’s schedule. This improves prioritisation and stakeholder buy-in.

AI can be used to detect anomalies and unusual patterns in large datasets. It surfaces items for auditors to investigate that conventional sampling would be unlikely to catch.

AI helps gather and organise audit evidence. It also drafts findings and reports from the underlying work. This reduces the documentation burden, while keeping the auditor responsible for the conclusions. 

Continuous auditing uses automated monitoring of key controls and indicators to flag deterioration between formal audits, allowing audit to engage when something changes rather than waiting for the next scheduled review.

A sharper independence problem for the third line 

Internal audit is expected to assure the firm’s use of AI while using AI itself. That raises a clear independence challenge. Audit cannot rely on a tool it has not validated and tested. The function must understand a tool’s logic, limits and failure modes. Outputs must be traceable so reviewers can follow how conclusions were reached. Professional scepticism is essential. Audit should hold its own tools to at least the same standard it expects of others.   

Handled with discipline, AI-strengthened validation and traceability strengthens independence. An opinion based on full-population examination and a clear audit trail is more defensible than one based on inference from samples. 

Quality assurance and professional standards 

Audit work faces external inspection and professional standards that many other teams do not. AI does not lower that bar. Functions need documented methods that define when and how AI may be used. Tools require validation, ongoing monitoring and evidence of performance. Documentation must allow external reviewers to assess the work. Consistent methods reduce variation and lift overall quality. AI can also speed up onboarding by embedding established guidance for junior auditors. 

The case for acting

For internal audit, AI delivers stronger, more credible assurance by enabling full‑population testing that improves coverage and uncovers patterns sampling misses. Audit data analytics make planning evidence‑led and automate routine testing, freeing experienced auditors for judgement and investigation. With robust model validation, full traceability and disciplined governance, AI‑based opinions are more defensible and make the third line more valuable to the board.

Did you find this useful?

Thanks for your feedback