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10 Common Tax Return Mistakes Australian Businesses Should Avoid This Year

Tax return mistakes Australian businesses make

The most common tax return mistakes Australian businesses make include under-reporting income, mixing personal and business funds, missing tax lodgment deadlines, and failing to keep adequate records. Each of these can trigger ATO scrutiny, penalties, or unwanted cash flow pressure. The good news is that all of them are avoidable with the right habits and the right support.

The ATO has flagged 2026 as a year for small businesses to reset their compliance habits. With the small business income tax gap sitting at $27.2 billion, much of it driven by avoidable errors, now is a good time to check your business isn’t making the same mistakes as everyone else.

Here are the ten tax return mistakes to avoid this year, and how to fix them before they cost you.

1. Under-reporting or omitting income

The ATO continues to see cases where income is left off tax returns, particularly among businesses that accept cash payments or keep inconsistent records. Every dollar of business income needs to be reported, regardless of how it was received. If your record-keeping has gaps, this is often where the problem starts.

2. Relying on the “shoebox” method

Paper receipts stuffed in a drawer are one of the most common tax return mistakes to avoid. Digital record keeping isn’t just more convenient; it’s increasingly what the ATO expects. Sole traders can use tools like the ATO app’s myDeductions feature to keep records accurate and current throughout the year, rather than scrambling at tax preparation time.

3. Mixing personal and business expenses

Blurring the line between personal and business spending makes your tax return harder to prepare accurately and easier to get wrong. Separate accounts and clear expense categorisation save time and reduce the risk of an incorrect claim.

4. Not setting aside funds for GST and PAYG

Cash flow remains one of the biggest pressure points for small businesses, with many owners scrambling at business activity statement (BAS) time because funds for GST or PAYG withholding haven’t been set aside. Keeping a separate account for these obligations makes it far easier to meet them without dipping into money that was never really yours to spend.

5. Using GST or PAYG withholding to fund the business

It can feel like a short-term fix, but using collected GST or employee PAYG withholding to cover cash flow shortfalls creates bigger problems down the track. These are tax time mistakes to avoid that tend to compound, making it harder to recover once your obligations fall due.

6. Overclaiming tax deductions

Claiming expenses that aren’t genuinely business-related, or claiming the business portion of a mixed-use expense incorrectly, is one of the more common tax return mistake penalties waiting to happen. If you’re unsure whether something is deductible, or how to apportion it, check before you lodge tax return.

7. Getting the instant asset write-off wrong

Eligibility rules and thresholds for the instant asset write-off change and are easy to misapply. Incorrectly timing or claiming asset purchases is a frequent source of amendments and, in some cases, penalties.

8. Missing tax lodgment and payment deadlines

Late BAS, super guarantee, or tax return lodgments attract penalties and interest, and they signal to the ATO that a business may need closer attention. If your business pays contractors in construction, cleaning, IT, courier, or security services, don’t forget the Taxable Payments Annual Report (TPAR) — it’s a separate lodgment with its own deadline and its own penalties for missing it. Setting calendar reminders for key dates is a simple habit that prevents avoidable stress.

9. Ignoring ATO debt instead of engaging early

Small business tax debts continue to grow nationally, and the ATO has been clear that it is not a cheap source of finance. If your business can’t pay in full or on time, the biggest mistake is doing nothing. Engaging with the ATO or a registered tax practitioner early keeps your options open.

10. Not preparing for Payday Super

From 1 July 2026, businesses are required to pay employees their super guarantee each payday rather than quarterly. Businesses that haven’t reviewed their payroll systems and super processes risk falling behind from day one. This is one of the newer tax return mistakes for 2026, and getting ahead of it now avoids a scramble later.

Why do these tax return mistakes keep happening?

Most tax return mistakes come down to two things: inconsistent record-keeping and leaving compliance to the last minute. Businesses that build simple, consistent habits throughout the year, rather than treating tax time as a once-a-year scramble, are far less likely to make costly errors.

How can Australian businesses avoid tax return mistakes?

The most effective way to avoid common errors is to seek advice from a registered tax practitioner early, rather than after a mistake has already happened. A practitioner who understands your business can help you stay across the ATO’s quarterly-updated small business compliance focus areas and flag risks before they become problems.

Get it right this year

Avoiding tax return mistakes isn’t about having a perfect system, but about having consistent habits and the right support when things get complex. If your business wants a second set of eyes on your record-keeping, tax deductions, or compliance calendar before this year’s return, get in touch with the Befree team to see how we can help.

FAQs

What happens if I make a mistake on my business tax return in Australia?
Minor errors can usually be corrected through an amendment. More serious or repeated mistakes, particularly around under-reported income, can attract penalties and closer ATO attention.
Yes. Businesses can request an amendment to a previously lodged tax return. Acting quickly and transparently is generally viewed more favourably than waiting to be contacted by the ATO.
Not always. The ATO distinguishes between honest errors and deliberate non-compliance. That said, penalties become more likely where record–keeping is poor or where the same mistakes are repeated year after year.
Ideally, more than once a year. Reviewing records, cash flow, and obligations quarterly, in line with BAS cycles, makes end-of-year tax time far less stressful.