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Latest estimate and trends for the individuals not in business tax gap

Understanding the results from the latest individuals not in business income tax gap estimate.

Last updated 28 October 2026

Individuals not in business population

For 2023–24 we estimate a net gap of 7% or $16 billion for individuals not in business. This means taxpayers paid around 93% of the total theoretical tax.

The population for this gap is defined as taxpayers who mainly receive salary and wages, with some other income, including:

  • non-business income from the sharing economy
  • 'passive income' which can include
    • dividends
    • interest
    • rental income.

To avoid double-counting, we exclude individuals that form part of the high wealth private groups. See how we cover these individuals separately in the High wealth income tax gap.

This income tax gap is part of our overall tax performance program. Find out more about the concept of tax gaps and latest gaps available at Australian tax gaps – overview.

Overview of the latest estimate

Our current gap estimate is based on findings from our random enquiry program. We found that adjustments were made in both tax agent and self-prepared income tax returns, including:

  • incorrect deduction claims for work-related or rental property expenses (or both)
  • careless income tax return administration or preparation.

Lack of connection to income earned or substantiation for expenses were also significant issues.

Work-related expenses continue to be the single largest contributor to the tax gap before accounting for any corrective action from us. They account for $5.2 billion of the gross tax gap, with errors relating to:

  • incorrect claims of work-related expenses due to lack of connection to income producing activities
  • poor record keeping
  • not apportioning claims to account for private use.

Another key contributor was unreported income from hidden wages, which is part of the shadow economy. It contributed around $4 billion in 2023–24 or 23% of the gross tax gap.

While the amounts over-claimed and under-reported by individual taxpayers may be small, collectively across a large population the overall revenue impact is significant.

Table 1: Income tax gap – individuals not in business, 2015–16 to 2023–24

Element

2015–16

2016–17

2017–18

2018–19

2019–20

2020–21

2021–22

2022–23

2023–24

Population (m)

11.0

11.3

11.6

11.9

12.0

11.9

12.0

12.3

12.7

Theoretical liability ($m)

136,288

140,967

152,571

156,732

165,221

165,050

179,273

207,343

230,108

Voluntarily Reported ($m)

126,198

130,510

141,578

146,156

153,961

153,789

167,376

192,302

212,734

Amendments ($m)

801

998

804

716

586

846

1,084

1,561

1,738

Total reported ($m)

126,999

131,508

142,383

146,872

154,547

154,635

168,460

193,863

214,472

Long term non-payment ($m)

291

336

252

250

203

253

304

324

372

Expected collections ($m)

126,708

131,171

142,131

146,623

154,343

154,382

168,156

193,539

214,101

Net gap ($m)

9,580

9,796

10,440

10,110

10,878

10,668

11,117

13,804

16,008

Net gap (%)

7.0

6.9

6.8

6.5

6.6

6.5

6.2

6.7

7.0

Assessment gap ($m)

9,289

9,460

10,188

9,860

10,675

10,414

10,813

13,480

15,636

Assessment gap (%)

6.8

6.7

6.7

6.3

6.5

6.3

6.0

6.5

6.8

Payment gap ($m)

291

336

252

250

203

253

304

324

372

Payment gap (%)

0.2

0.2

0.2

0.2

0.1

0.2

0.2

0.2

0.2

Gross gap ($m)

10,382

10,794

11,244

10,825

11,464

11,514

12,201

15,365

17,746

Gross gap (%)

7.6

7.7

7.4

6.9

6.9

7.0

6.8

7.4

7.7

Note: values are subject to rounding error.

Figure 1 displays these trends as a percentage.

Figure 1: Gross and net tax gap percentage – individuals not in business, 2015–16 to 2023–24

The gross and net gap in percentage terms as outlined in Table 1.

Internationally, tax gaps are difficult to compare, due to:

  • large variations in legal and tax systems
  • market definitions
  • availability of data
  • methodologies used.

While this estimate is not directly comparable for these reasons, we use a methodology that is used in similar tax regimes. They are considered best practice when estimating from large and homogenous taxpayer populations.

The random enquiry program

In our random enquiry program, we randomly select and profile a sample of individual taxpayers who are not in business. Taxpayers in the sample identified as low risk are not inconvenienced by being investigated further.

We verify details where we can confirm the income tax return data by matching all material amounts with our third-party data. We refer to these taxpayers as the 'verified' portion of the sample. While we do not manually review these taxpayers, they remain part of our overall sample, contributing to our gap analysis.

The rest of the sample progress to a review, the random enquiry program, from which we gather information. We estimate the gap by using the incidence rate of adjustments and mean value of amendments resulting from non-compliance. Adjustments refer to changes we make to items on a tax return to correct errors identified in the review process.

This method provides insights into the:

  • value of non-compliance
  • proportion of the sample, and by extension the population, who are incorrectly reporting.

Findings from the random enquiry program

From 2013–14 to 2022–23, we undertook 5,215 random enquiry program reviews across a representative sample of the individuals not in business population. The 2 years from 2021–22 to 2022–23 comprised 1,090 cases that informed our most recent year's estimate. Of these cases, 790 involved manual reviews, while 300 were verified using third-party data.

This sample was large enough to provide a suitable representation of the population. It is proportionally similar to, or greater than, other comparable countries' programs (for example, UK and US).

During the selection process, we stratified the population across all income bands to ensure the overall population was appropriately represented. Taxpayers in the tax-free threshold and low to very high incomes were represented as well as taxpayers with rental properties.

The sample includes taxpayers who lodged through various channels. The proportion of agent-prepared income tax returns in the random sample was representative of the total individuals not in business population.

We used a confidence interval to quantify the precision of the estimate. See more about gap limitations. We're confident that the true value of the net gap in 2023–24 lies between 5.6% to 8.3%, or $12.7 billion to $19.3 billion.

In the 2021–22 to 2022–23 sample, the incidence of adjustment was 69%, with 81% of agent-prepared returns being adjusted. This compares with 54% of returns adjusted for people who self-prepared their tax return.

On average we made 2.9 item adjustments per income tax return. The median increase to taxpayers' taxable income (income less deductions) was $1,582. While individually this amount may not be large, when aggregated across the whole population, the effect is significant.

There were 39 cases where we adjusted solely in the taxpayer's favour.

Table 2: Overview of the 2021–22 to 2022–23 random enquiry programs for individuals not in business

Cases

Sample
(no.)

Agent-prepared sample
(no.)

Self-prepared sample
(no.)

Agent-prepared sample
(%)

Self-prepared sample
(%)

Manually reviewed cases

790

519

271

66

34

Verified cases

300

104

196

35

65

Total finalised cases

1,090

623

467

57

43

Table 3: Comparison of the incidence of adjustment in all finalised cases for the 2021–22 to 2022–23 random enquiry programs for individuals not in business

Cases

Full sample
(no.)

Agent-prepared sample
(no.)

Self-prepared sample
(no.)

Full sample
(%)

Agent-prepared sample
(%)

Self-prepared sample
(%)

Cases with adjustments

756

503

253

69

81

54

Cases with adjustments only in the taxpayer's favour

39

23

16

4

4

3

Note: The distribution of item adjustment values shows that 33% were $150 or less and 30% were over $1,000.

Table 4: Distribution of item adjustment rates and values in the 2021–22 to 2022–23 random enquiry programs (percentage) for individuals not in business

Range of adjustments

% of all adjustments

% of values adjusted

$0–$50

19

<1

$51–$150

14

1

$151–$300

13

1

$301–$500

11

2

$501–$1,000

14

4

More than $1,000

30

92

Based on the analysis and findings of the random enquiry program and insights from our overall engagement program, we can highlight the themes that contribute to the gap.

When we look at the most recent tax gap year estimate, we draw on the last 2 years of the sample only. Figure 2 shows a breakdown of the individuals not in business tax gap by the different drivers for the most recent year's estimate.

Figure 2: Net tax gap breakdown by driver for individuals not in business, 2023–24

The breakdown of the net tax gap by the 4 main drivers: work-related expenses at 28%, rental expenses at 14%, hidden income at 27% and other at 31%.

What is driving the gap

Through our analysis, we found several main areas that contribute to the individuals not in business tax gap:

Work-related expenses

Work-related expenses are a key component of the individuals not in business income net tax gap. The work-related expenses net gap estimate is $4.5 billion for 2023–24. The average adjustment to car expenses has increased, contributing to this finding.

Each case can have multiple adjustments across the tax return. Of the 3,121 adjustments in identified cases, around 73% related to deduction items, including rental deductions. Around 44% or 1,375 were made at work-related expense items. Of those adjustments, 66% or 911 were made in agent-prepared returns.

Common reasons for adjustments in the random enquiry program include:

  • claims for ‘standard’ deductions where exceptions to substantiation provisions exist, for example claiming up to $300 in work-related expenses without spending the money
  • no link between the expense and taxpayer earning their income
  • incorrect apportionment of private use versus work-related use – claiming expenses that aren’t apportioned for personal use, such as 100% of mobile phone expenses
  • claims that appeared legitimate, but could not be substantiated because there are no receipts, logbook or diary entries
  • claims for expenses that were actually paid for or reimbursed by the employer.

Work-related expenses adjustments and reasons

The following 2 pie charts (Figure 3 and Figure 4) display the number of adjustments to work-related expense items and the reasons for these adjustments.

The highest rate of adjustments was for 'other expenses', in particular, incorrect claims for home office, mobile phone and internet. Claims for clothing and car were also frequently adjusted.

Figure 3: Number of adjustments to work-related expenses

A breakdown of the types of work-related expenses adjustments and number of times they occurred: car 222, travel 99, clothing 399, self-education 62 and other 593.

Figure 4: Reasons for work-related expense adjustments

The percentage breakdown of the reasons for adjustments made for work-related expenses: substantiation 36%, nexus and substantiation 32%, nexus 9%, over claimed 5%, calculation error 8% and other reasons combined 10%.

Undeclared income

Omitted income, particularly cash wages and income from the sharing economy, also contributes to the tax gap.

Some people don't declare income and payments to avoid paying the right amount of tax or super. For example, some businesses may pay their employees 'cash-in-hand’ and some taxpayers do not report all the cash income they earn.

We estimate the portion of the tax gap for 2023–24 attributable to unreported income was $4.4 billion. This includes hidden wages as well as an estimate of income not reported from those operating outside of the system.

Identifying non-declared wages is difficult, even in a random enquiry program. We take a different approach to account for the impact of undeclared cash wages, an aspect of the shadow economy.

To help us estimate the undeclared wages in the individuals not in business population, we draw on 2 of our administrative gaps:

Our approach is incorporated in our shadow economy strategy.

Other findings and observations

Observations from our broader compliance activities reinforce findings from our random enquiry program. This further supports our understanding of what is driving the gap.

We are observing higher volumes of capital gains tax adjustments in our random enquiry program, coinciding with higher volumes of net capital gains being reported. Where these relate to real property they can have a significant impact on the tax gap due to the large value of transactions.

Deductions for rental property expenses are also a key contributor. The rental component of the net tax gap is estimated to be $2.2 billion. The average adjustment to interest expenses and ‘other’ rental deductions has increased, contributing to this finding.

Our observations indicate that the most common reasons for adjustments to rental items on a tax return are:

  • no or incorrect apportionment of the loan interest costs where the loan was re-financed for private purposes
  • claiming costs as repair rather than a capital works deduction
  • not apportioning expenses for private use of the property.

For previously published tax gap figures, see Australian Tax Gaps – Data.gov.auExternal Link

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