ATO Audit in Australia: What Triggers One, How Far Back They Can Go, and What to Do

An ATO audit or review is the process by which the Australian Taxation Office examines your tax affairs to verify that the information in your tax returns and activity statements is correct. Most Australians never experience a formal full audit. The majority of ATO contacts are targeted review letters requesting documentation for a specific claim or cross-checking a figure that doesn't match what the ATO received from a third-party data source.

This guide explains what actually happens in an ATO audit, the key questions people search for (how far back can the ATO go, what are the time limits, how common is an audit), what triggers ATO attention, the penalties that apply, and what to do if you receive an audit notice.

What Is the Difference Between an ATO Review and an ATO Audit?

The ATO uses two types of compliance activity, and they have importantly different implications:

ATO review (the most common): a targeted examination of a specific aspect of your tax return. Usually begins with a letter asking you to substantiate a particular claim or explain a discrepancy. A review is not a full audit; it is focused on one or a few issues. Most reviews resolve quickly when you provide the requested documentation. If the ATO is satisfied, the review closes. If they find a problem, it may escalate to a formal audit or an amended assessment.

ATO audit (less common): a comprehensive examination of your financial records across multiple years or all aspects of your tax position. A formal audit may involve the ATO requesting all financial records, accessing third-party data, and potentially conducting interviews. Audits are typically reserved for situations where the ATO has reason to believe there are significant compliance issues.

The ATO also conducts continuous data matching, comparing information on your tax return with data it receives from employers, banks, share registries, state revenue offices, and online platforms. If a discrepancy is identified, you may receive an auto-generated letter without any human reviewer initially involved.

How Far Back Can the ATO Audit? ATO Review Periods Explained

The ATO’s ability to review and amend your tax assessments is subject to the standard review period set by the Tax Administration Act 1953. This is the period during which the ATO can amend a tax assessment. After the review period expires, the ATO cannot amend an assessment (except in cases of fraud or evasion).

How Often Does the ATO Audit Individuals?

The ATO does not publish a precise rate of formal individual audits, but it confirms that it contacts approximately 2 million taxpayers each year in relation to their tax returns. The vast majority of these contacts are not full audits they are data matching notifications, reviews of specific claims, or requests for supporting documentation.

The probability of a full formal audit for a typical Australian individual is relatively low in any given year.

However, certain behaviours significantly increase your probability:

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  Claiming deductions that are dramatically higher than the ATO’s benchmark for your occupation
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  Declaring income that doesn't match the data the ATO receives from third parties
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  Operating a cash-intensive business with low declared income
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  Having been audited before and found to have errors
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  Being subject to an anonymous tip-off

The ATO’s compliance program focuses on areas where it believes tax is most likely to be incorrectly reported. Annual focus areas are published and updated, so taxpayers in those categories face heightened scrutiny in particular years.

What Triggers an ATO Audit or Review?

The ATO uses a combination of data matching, risk profiling, and industry benchmarks to identify returns that warrant closer examination. The following are the most common triggers:

ATO Annual Focus Areas: What the ATO Is Watching

Each year, the ATO announces its compliance focus areas, specific deduction types, income categories, or industries where it believes errors (both accidental and deliberate) are most common. Being in a focus area does not guarantee a review, but claims in these areas are more likely to be examined.

Recent and ongoing ATO focus areas for individuals include:

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  Work-from-home expenses: the ATO continues to scrutinise WFH claims, particularly whether taxpayers are maintaining contemporaneous records of actual hours worked from home. The ATO has explicitly stated it will not accept estimated or reconstructed records for the fixed rate (70c/hr) method
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  Rental property deductions: the ATO identifies errors in over 80% of rental property tax returns it examines. Common issues: claiming personal expenses, claiming capital improvements as repairs, overstating interest deductions, and incorrectly apportioning mixed-use expenses
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  Cryptocurrency: the ATO receives data from Australian crypto exchanges. Unreported crypto disposals (including crypto-to-crypto swaps) are a significant compliance gap
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  Gig economy income: income from Uber, Airbnb, Airtasker, Deliveroo, and similar platforms that is not declared in full
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  Share market income: dividend income, especially from Dividend Reinvestment Plans (DRPs), where shares received are assessable income even though no cash changes hands
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  Cash businesses: hospitality, retail, and trade businesses with significant cash turnover are a perennial focus area

What Happens During an ATO Audit?

Stage 1: Initial Contact

Most ATO audits and reviews begin with a letter or phone call. The ATO identifies the specific issue or issues they want to examine and provides a deadline for your response (typically 28 days). Do not ignore ATO correspondence. Failing to respond by the deadline can result in the ATO making assumptions in their favour and issuing a default assessment.

Stage 2: Documentation Reques

The ATO will ask you to provide specific records: receipts, bank statements, logbooks, invoices, employment records, or whatever is relevant to the claims under review. You must be able to produce documentation that was in your possession at the time you lodged the return, not documentation you locate or create after the ATO contacts you. This is why the record-keeping obligation exists: you must have evidence at lodgment, not just when challenged.

Stage 3: Assessment or Resolution

If your documentation is satisfactory, the ATO will close the review and notify you. If the ATO identifies errors, whether in your favour or theirs, they issue an amended Notice of Assessment. If additional tax is owing, General Interest Charge (GIC) accrues from the original due date of the relevant assessment. From 1 July 2025, GIC is no longer deductible as a business expense. Shortfall penalties also apply based on the level of care taken (see penalty table below).

Stage 4: Penalties

What to Do If You Receive an ATO Audit Notice

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  Do not ignore the letter: ignoring ATO correspondence leads to default assessments and additional penalties. There is always a response deadline typically 28 days
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  Gather your documentation immediately: locate all records relevant to the specific claims under review. Organise them chronologically and by category. If any records are missing, note this and prepare to explain why
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  Engage a registered tax agent immediately: you have the right to be represented by a registered tax agent throughout an ATO audit. A tax agent understands how to communicate with the ATO, what documentation satisfies ATO requirements, and how to contest incorrect assessments
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  Respond within the deadline: if you need more time, request an extension in writing before the deadline passes. The ATO generally grants reasonable extension requests when asked proactively
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  Do not provide more than requested: respond to the specific questions asked. Providing additional information beyond what the ATO requested can open new areas for review
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  If you disagree with an assessment: you have 60 days from the date of the amended assessment to lodge a formal objection. The ATO must then review your objection. If you remain dissatisfied, you can request an independent ATO review or apply to the Administrative Appeals Tribunal (AAT)

How to Reduce Your ATO Audit Risk

Declare All Income

The ATO’s data matching program is extensive. Bank interest, employer payments, dividends, government payments, Airbnb income, Uber income, cryptocurrency disposals, and foreign income are all reported to the ATO through third-party data sources. Any income that appears in these sources but not in your tax return creates a discrepancy that the ATO will investigate. The safest approach is to declare every source of income, no matter how small.

Claim Only What You Can Substantiate

Every deduction you claim must have written evidence in your possession at the time you lodge (not after you receive an ATO letter). This means receipts, invoices, bank statements, logbooks, or diary entries, depending on the deduction type. The ATO can request documentation years after lodgment, and if you cannot produce it, the deduction is disallowed, plus interest and penalties may apply.

Use a Registered Tax Agent

Taxpayers who use a registered tax agent are less likely to claim ineligible deductions, miss income, or make calculation errors. A registered tax agent is familiar with current ATO focus areas and the documentation requirements for each deduction type. They also extend your lodgment deadline (up to 15 May the following year) and can represent you if the ATO contacts you. Our registered tax agents in Adelaide prepare and lodge individual and business returns for clients across South Australia.

Keep Complete Records for 5 Years

The 5-year record-keeping obligation (from the date you lodge each return) ensures you have documentation available for the full standard review period and beyond. For assets with CGT implications, keep acquisition records for the full period of ownership plus 5 years after disposal. See our complete ATO record keeping guide for the full retention period table by record category.

Be Consistent Year to Year

Large changes in your deductions, income, or business expenses from one year to the next attract ATO attention. If you have a genuinely different year (a major asset purchase, a change in work pattern, unusually high medical expenses), be prepared to explain the change with documentation. Consistent patterns with clear explanations are far less likely to trigger a review than unexplained swings.

If You Think a Prior Return Has an Error

Voluntary disclosure before the ATO contacts you significantly reduces penalties and demonstrates good faith. If you believe an error exists in a previously lodged return, contact the ATO or engage a tax agent to lodge an amendment. Our second look assessment service reviews previously lodged returns and, where corrections are warranted, lodges amendments before the ATO identifies the issue.

How The Kalculators Can Help

Our registered tax agents prepare tax returns with ATO audit risk in mind: ensuring deductions are correctly categorised, substantiated, and within ATO benchmarks for your occupation or industry. We apply ATO’s current focus areas as a checklist when preparing every return.

If you have received an ATO review or audit notice, contact us immediately. We manage ATO communications on your behalf, gather and present documentation, and represent your interests throughout the review or audit process. Registering with a tax agent also provides access to the ATO’s extended lodgment schedule, which gives you additional time to prepare accurate returns before the deadline.

For clients who have lodged their own previous returns and want to verify their position before the ATO does, our second look assessment service provides a professional review of lodged returns and lodges amendments where corrections are warranted, a voluntary disclosure before the ATO makes contact.