The 5% Rule and Materiality
Understanding materiality is one of the most important aspects of auditing, yet many organisations mistakenly believe there is a simple ‘5% rule’ that determines whether an issue matters in a financial report.
Why Professional Judgement Matters
Many people searching for audit materiality encounter references to a “5% rule”. While percentages may be used as planning benchmarks during an audit, Australian auditing and reporting standards do not prescribe a fixed percentage for determining materiality. Materiality is ultimately a matter of professional judgement, context and the needs of users of financial reports.
What Is Materiality?
In simple terms, materiality asks:
“Would this information influence the decisions of someone reading the financial statements?”
If the answer is yes, the matter may be material.
Materiality affects many areas of an audit including:
audit planning
risk assessment
testing procedures
disclosure decisions
reporting outcomes
governance communication
Materiality is one of the most important professional judgements made during an audit.
Is There Really a “5% Rule”?
The phrase “5% rule” is commonly discussed online and is often used as a simplified explanation of audit materiality.
However, there is no formal auditing standard that states:
“Anything under 5% is immaterial.”
In practice, auditors may use percentages as a starting point when planning an audit, but those percentages are not automatic rules.
Different organisations may require different benchmarks depending on factors such as:
revenue
surplus or deficit
total assets
expenses
equity
the nature of the organisation
For example, a sporting association, charity, school P&C or incorporated association may all have very different risk profiles and reporting expectations even where their financial size is similar.
Why Professional Judgement Matters
Materiality is not just about the dollar amount.
Some matters may be material because of their nature rather than their size.
Examples may include:
fraud
related party transactions
misuse of grant funding
governance breaches
conflicts of interest
non-compliance with legislation
committee remuneration
going concern issues
A relatively small transaction may still be highly material if it changes how members, regulators, donors, lenders or committees understand the financial position or governance of the organisation.
Quantitative vs Qualitative Materiality
Auditors often consider both:
Quantitative Materiality
This relates to the numerical size of an item.
For example:
a large unexplained expense,
a significant understatement of revenue,
or an incorrect asset balance.
Qualitative Materiality
This relates to the nature or context of the issue.
For example:
an undisclosed related party payment,
unauthorised committee spending,
or a breach of funding conditions.
Even where the dollar value is small, the issue may still influence the decisions of users of the financial report.
Materiality and Modern Financial Reporting
The concept of materiality is now extending beyond traditional financial statement audits into broader governance and reporting frameworks.
Australia’s new climate-related financial disclosure framework focuses on whether information could reasonably influence the decisions of users of financial reports.
This reflects a broader shift in financial reporting:
governance matters,
sustainability risks,
climate-related disclosures,
and operational risks
may all become material depending on their potential impact on the organisation and its stakeholders.
For committees, boards and management, this means materiality is becoming increasingly linked to transparency, governance and decision-making — not simply percentages.
A Practical Example
A $2,000 coding error may be immaterial for a large organisation with millions in annual revenue.
However, a small undisclosed payment to a related party, breach of grant conditions or governance failure may still be material regardless of size because of the nature of the transaction and the effect it may have on users of the financial report.
Materiality Is About Users and Decisions
At its core, materiality is about whether information matters to the people relying on the financial report.
That is why auditing standards rely on professional judgement rather than fixed mathematical rules.
Percentages may assist during audit planning, but they are only one part of the overall assessment.
A proper materiality assessment requires consideration of:
size,
context,
governance,
risk,
compliance,
and the needs of users of the financial statements.
For committees, treasurers and boards, understanding materiality helps explain why auditors may focus heavily on some issues that appear numerically small — while spending less time on larger balances that present lower risk.
Technical Note for Auditing Students: ASA 320 Materiality
Australian Auditing Standard ASA 320 Materiality in Planning and Performing an Audit requires auditors to apply materiality when planning and conducting an audit of a financial report.
ASA 320 recognises that misstatements — including omissions — are considered material if they could reasonably be expected to influence the economic decisions of users taken on the basis of the financial report.
Importantly, ASA 320 does not prescribe a fixed numerical percentage or “5% rule” for determining materiality.
Instead, auditors apply professional judgement in determining:
overall materiality,
performance materiality,
tolerable misstatement levels,
and the nature, timing and extent of audit procedures.
In practice, auditors may use benchmarks such as:
profit or surplus,
total revenue,
total expenses,
net assets,
or equity
as a starting point during audit planning. However, qualitative factors must also be considered.
Examples of qualitatively material matters may include:
fraud,
related party transactions,
breaches of legislation,
non-compliance with funding agreements,
governance failures,
or matters affecting going concern.
ASA 320 also requires materiality to be reassessed throughout the audit if circumstances change or if additional information becomes available.
For auditing students, one of the key concepts to understand is that materiality is fundamentally linked to:
professional judgement,
audit risk,
and the information needs of users of the financial report.
Materiality is therefore not simply a mathematical calculation, but a core auditing concept that influences audit planning, testing, evaluation of misstatements and ultimately the auditor’s opinion.
Academic References
APA 7th Edition
O’Connor, J. (2026, May 21). The 5% rule and materiality — Why professional judgement matters. J O’Connor Pty Ltd. https://www.joconnorptyltd.com/blog/the-5-rule-and-materiality
Harvard Referencing
O’Connor, J. 2026, The 5% rule and materiality — Why professional judgement matters, J O’Connor Pty Ltd, viewed 21 May 2026, https://www.joconnorptyltd.com/blog/the-5-rule-and-materiality.
AGLC4 (Australian Guide to Legal Citation)
Jason O’Connor, ‘The 5% Rule and Materiality — Why Professional Judgement Matters’ (Blog Post, J O’Connor Pty Ltd, 21 May 2026) https://www.joconnorptyltd.com/blog/the-5-rule-and-materiality.
Chicago Style
O’Connor, Jason. “The 5% Rule and Materiality — Why Professional Judgement Matters.” J O’Connor Pty Ltd. May 21, 2026. https://www.joconnorptyltd.com/blog/the-5-rule-and-materiality.