The Biggest Tax Return Mistakes Australians Make (And How to Avoid Them)

Tax Time Mistakes Are More Common Than You Think

Most taxpayers want to do the right thing. Yet every tax season, the ATO identifies thousands of mistakes that result in amended assessments, delayed refunds, additional tax liabilities and, in some cases, penalties and interest.

These errors are rarely deliberate. More often, they happen because taxpayers misunderstand the rules, assume something is deductible because it relates to work, or rely on incomplete information when preparing their return.

Tax has also become more complicated in recent years. Many Australians now earn income from multiple sources, including investment portfolios, rental properties, rideshare driving, food delivery services, freelance work, online marketplaces, cryptocurrency and content creation. At the same time, the ATO's data-matching capabilities continue to expand, making it easier to identify discrepancies between the information it receives from third parties and what taxpayers report in their returns.

The good news is that most common tax return mistakes are entirely preventable. Understanding where taxpayers commonly go wrong can help you lodge an accurate return and avoid unnecessary problems later.

Even taxpayers with relatively straightforward tax affairs can overlook deductions, misunderstand changing tax rules or rely on incomplete information. Having your return prepared by a tax professional provides added confidence that your return is accurate, compliant and includes every deduction you're entitled to claim.
 

10 Common Tax Return Mistakes Australians Should Avoid

1. Focusing on the Biggest Refund Instead of the Correct Tax Outcome

One of the biggest misconceptions at tax time is that a larger refund automatically means you've lodged a better tax return.

In reality, your refund simply reflects the difference between the tax you've already paid throughout the financial year and your actual tax liability. A large refund may indicate that too much tax was withheld from your income, while a smaller refund - or even a tax bill - doesn't necessarily mean anything has gone wrong.

The objective should never be to maximise your refund by stretching deduction claims. Instead, your goal should be to prepare an accurate tax return that correctly reports your income and claims every deduction you're legally entitled to.

Claiming deductions that don't meet ATO requirements may increase your refund initially, but it can also lead to amended assessments, interest charges or penalties if your return is reviewed later.

How to avoid this mistake
 

• Focus on claiming legitimate deductions supported by records.
• Report all taxable income accurately.
• Review your return carefully before lodging.
• Remember that compliance is more important than chasing a larger refund.

 

2. Assuming Every Work-Related Expense Is Tax Deductible

One of the most common misunderstandings involves work-related deductions.

Simply because you purchased something for work - or your employer expected you to have it - doesn't automatically make it deductible.

Generally, the ATO requires three conditions to be satisfied before you can claim a work-related expense:
 

• you paid for the expense yourself
• the expense wasn't reimbursed by your employer
• the expense has a direct connection to earning your assessable income.

 
Many everyday expenses remain private, even if they're used at work.

Examples commonly misunderstood include:
 

• business suits and corporate clothing
• everyday shoes
• handbags and briefcases used for ordinary commuting
• general fitness expenses and gym memberships
• personal grooming and cosmetics.

 
On the other hand, compulsory uniforms, occupation-specific clothing and protective equipment may be deductible where the relevant conditions are met.

How to avoid this mistake
If you're unsure whether an expense is deductible, it's worth checking before you lodge. Our Tax Experts can help you distinguish between private expenses and legitimate work-related deductions. Whether you prefer to visit one of our 400+ offices or connect with our Online Tax Experts, H&R Block makes getting your tax return right easy.
 

3. Not Keeping Enough Records to Support Your Claims

Good record-keeping is one of the simplest ways to reduce your risk at tax time.

While electronic payments have made receipts easier to retain, many taxpayers still rely on estimates when calculating deductions for working from home, motor vehicle travel, phone usage or internet expenses.

Statements such as:
 

• "I usually worked from home."
• "I probably used my phone for work around half the time."
• "I think I travelled about 3,000 kilometres."

may sound reasonable, but estimates alone generally aren't enough if the ATO asks you to substantiate your claims.

Depending on the deduction, you may need receipts, diary records, logbooks, invoices, bank statements or other documentation.

Good records also make it easier to prepare your return accurately and ensure you don't overlook deductions you're entitled to claim.

How to avoid this mistake
Maintain your records throughout the year rather than trying to reconstruct them at tax time. Digital tools such as H&R Block's free ReceiptHub app can help you store receipts, track work-related travel and record working from home hours in one place.
 

4. Forgetting to Declare All Taxable Income

Income doesn't stop with your salary.

Many Australians now earn money from multiple sources, including:
 

• freelance work
• consulting
• rideshare driving
• food delivery platforms
• online marketplaces
• rental properties
• bank interest
• dividends
• managed funds
• cryptocurrency transactions
• capital gains
• creator platforms and sponsorships.

 
Some taxpayers mistakenly assume that small amounts of income don't need to be declared or that income earned through digital platforms somehow sits outside the Australian tax system.

In most cases, if income is taxable, it must be included in your tax return.

The ATO receives data from employers, financial institutions, investment providers, government agencies and many online platforms, allowing it to compare third-party information against your lodged return.

How to avoid this mistake
Before lodging, review every source of income you've received during the financial year and confirm it has been included where required.
 

5. Assuming Pre-fill Means Your Tax Return Is Ready to Lodge

Pre-filled information is one of the easiest ways to save time when preparing your tax return. It automatically imports a range of information reported to the ATO, helping reduce manual data entry and making the lodgement process faster and more convenient.

However, pre-filled information is designed to help you complete your tax return - not replace the need to review it carefully.

The ATO receives information from employers, banks, private health insurers, government agencies, share registries and investment providers. While much of this information is automatically populated into your return, some information may still need to be added based on your individual circumstances.

For example, you may still need to include:
 

• income from freelance or contract work
• cash income
• some foreign income
• certain cryptocurrency transactions
• private asset sales that trigger capital gains tax (CGT)
• work-related deductions and other deductions that only you know about.

 
Pre-filled information may also continue to update as more data is reported to the ATO during tax time. That's why it's important to review your return carefully and ensure all of your income and deductions have been captured before you lodge.

How to avoid this mistake
If you're using our easy to use DIY Online Tax Express platform, take advantage of ATO pre-fill to save time, then review your return carefully against your own records before lodging. If you'd like additional peace of mind, Online Tax Adviser lets you complete your return online with the support of one of our Online Tax Experts, who can review your circumstances and help ensure your return is accurate before it's submitted.

6. Accidentally Claiming the Same Expense Twice

As tax software becomes more sophisticated, duplicate claims are becoming more common.

Many taxpayers now import information from bookkeeping software, upload receipts electronically or use pre-filled data. It's easy to forget an expense has already been included and manually enter it again.

Double claims can occur with:
 

• work-related expenses
• tax agent fees
• depreciation schedules
• private health insurance information
• expenses imported from accounting software
• reimbursed expenses that shouldn't be claimed at all.

 
Although these mistakes are usually accidental, they can create discrepancies that attract unwanted attention if your return is reviewed.

How to avoid this mistake
Review your deductions carefully before lodging. Having your return prepared or reviewed by a Tax Expert can also help identify duplicate claims and other common errors before they're submitted to the ATO.
 

7. Misunderstanding Rental Property Deductions

Rental property deductions remain one of the areas where taxpayers most commonly make mistakes.

Many property owners assume that any money spent on their investment property can be claimed immediately, but Australian tax law distinguishes between different types of expenditure.

For example:
 

• repairing part of an existing fence that's been damaged is generally considered a repair and may be deductible immediately
• replacing the entire fence with a brand-new structure is generally regarded as a capital improvement and is usually claimed over time rather than all at once.

 
The same principles apply to many renovation and maintenance projects.

Other common rental property mistakes include:
 

• claiming private expenses
• failing to apportion deductions where the property wasn't available for rent for the entire year
• incorrectly claiming borrowing costs
• overlooking depreciation opportunities
• misunderstanding the difference between repairs, maintenance and capital works.

 
Because rental property rules can be complex, it's important to consider the specific circumstances surrounding each expense.

How to avoid this mistake
Keep detailed records of all property-related expenditure, including invoices, settlement documents and loan statements. If you're undertaking renovations or significant repairs, seek advice from our Tax Experts before lodging your return to ensure the expenses are treated correctly.
 

8. Believing Everything You See on Social Media

Tax advice has become one of the fastest-growing categories of content on social media. Unfortunately, popularity doesn't always equal accuracy.

Every tax season, videos circulate claiming Australians can deduct everyday clothing, claim family holidays because they answered work emails or write off personal purchases with little or no connection to earning income.

These posts often oversimplify tax law or ignore the circumstances that determine whether a deduction is actually available.

Australian tax law is based on legislation and ATO guidance - not internet trends.

While social media can be useful for raising awareness about tax issues, it shouldn't be relied on as your primary source of tax advice.

How to avoid this mistake
If advice sounds too good to be true, it probably deserves further investigation. Speak to our Tax Experts before claiming a deduction.
 

9. Relying on Artificial Intelligence Without Verifying the Advice

Artificial intelligence is rapidly changing the way Australians research tax information.

AI tools can be helpful for explaining unfamiliar terminology, summarising complex concepts and providing general educational information. They can also save time when you're trying to understand how particular tax rules work.

However, AI has limitations.

Tax law depends heavily on the individual facts of each taxpayer's circumstances. Two people with seemingly similar situations can receive very different tax outcomes depending on factors such as how an asset is used, whether an expense has a private component or how income has been earned.

AI-generated responses may also rely on outdated information, misunderstand Australian tax law or present incorrect conclusions with confidence.

While these tools continue to improve, they shouldn't replace careful research or professional advice where significant tax decisions are involved.

How to avoid this mistake
Use AI as an educational tool rather than a substitute for making tax decisions. Always verify important information against current tax laws and consider seeking professional advice from our Tax Experts.
 

10. Leaving Your Tax Return Until the Last Minute

Preparing your tax return in a rush increases the likelihood of mistakes.

When taxpayers leave everything until the last minute, they're more likely to overlook income, miss eligible deductions, forget supporting documents or submit their return without reviewing it properly.

Whether you're completing your own tax return or using a Tax Expert, taking the time to check your information before lodging can help reduce errors and give you greater confidence that your return is accurate.

How to avoid this mistake
Start your tax return early and give yourself enough time to review it before lodging. If you're using Online Tax Express, make the most of features like ATO pre-fill to save time, then check your information carefully against your own records. If you'd prefer an experienced Tax Expert to prepare your return for you, H&R Block's Online Tax Adviser and in-office services can help ensure your return is accurate and complete before it's lodged.
 

Why These Mistakes Matter

Even seemingly minor errors can have consequences.

Depending on the circumstances, mistakes may result in:
 

• delayed tax refunds
• amended assessments
• additional tax becoming payable
• interest charges on outstanding tax
• administrative penalties
• requests from the ATO for supporting documentation.

 
Importantly, the ATO distinguishes between genuine mistakes and deliberate non-compliance. Taking reasonable care when preparing your tax return, maintaining appropriate records and responding promptly if further information is requested can help reduce your compliance risk.

For most taxpayers, accuracy isn't just about avoiding problems - it's also about ensuring they claim every deduction they're genuinely entitled to without overstepping the rules.
 

How to Reduce Your Risk at Tax Time

Following a few simple practices each year can help you prepare a more accurate tax return.

Before you lodge, make sure you:
 

• Declare all taxable income.
• Check that your pre-filled information is complete.
• Keep receipts and records for every deduction you claim.
• Only claim expenses that directly relate to earning your assessable income.
• Review your return before submitting it.
• Keep supporting records for the required retention period.
• Consider having your return prepared or reviewed by a tax professional before lodging.

 
While good record-keeping and careful preparation go a long way, even experienced taxpayers can misunderstand changing tax rules or overlook deductions. Having your return prepared or reviewed by a tax professional can provide additional confidence that your return is accurate, compliant and complete before it's lodged.

Why Professional Tax Advice Can Benefit Every Taxpayer

While some tax returns may appear straightforward, even relatively simple returns can involve deductions, offsets or reporting obligations that are easy to overlook. Tax laws also change regularly, meaning what applied last year may not apply this year.

Every tax return is unique. While professional advice can benefit all taxpayers, it becomes particularly valuable if you:
 

• earn income from more than one job
• operate a business or work as a sole trader
• receive freelance or contractor income
• own one or more rental properties
• buy and sell shares or other investments
• have cryptocurrency transactions
• receive foreign income
• have sold an investment asset during the financial year
• need to calculate capital gains tax
• have significant work-related deductions
• are unsure whether an expense is deductible.

 
Even if none of these situations apply, many Australians still choose to have their tax return prepared by H&R Block because they value the confidence of knowing their return has been prepared correctly, every eligible deduction has been considered and their return complies with current ATO requirements.

For many Australians, the value isn't simply having someone lodge their return - it's having the reassurance that an experienced Tax Expert has reviewed their circumstances and applied the latest tax rules correctly.

Our Tax Experts understand current tax legislation, keep up to date with changes to ATO guidance and can identify opportunities or issues that may not be obvious to someone preparing their own return.
 

Final Thoughts

Most tax return mistakes don't happen because taxpayers intentionally break the rules. They happen because tax law can be more complex than it first appears.

As Australians earn income from a growing range of sources and tax legislation continues to evolve, it's becoming increasingly important to understand what must be declared, which deductions are genuinely available and what records need to be kept.

The best tax return isn't necessarily the one that produces the biggest refund. It's the one that's accurate, complete and supported by evidence if the ATO ever asks questions.

Whether your tax affairs are straightforward or more complex, taking the time to get your return right is always worthwhile. For many Australians, working with a tax professional provides confidence that their return is accurate, compliant and includes every deduction they're entitled to claim under current tax law.

With more than 400 offices nationwide and the flexibility to lodge online with our Online Tax Experts, H&R Block makes it easy to get your tax return right, no matter how simple or complex your circumstances may be.