- Mixing Personal and Business Expenses
This one catches many business owners off guard. Using the same bank account or card for both personal and business purchases might feel convenient, but it creates a mess at tax time. Why it causes trouble: It becomes harder to separate genuine business expenses
You may accidentally miss deductions
The ATO may question the accuracy of your records
How to fix it: Open a dedicated business bank account and always keep personal spending separate. It makes bookkeeping much easier.
- Poor Record-Keeping
Lost receipts, incomplete invoices, and inconsistent bookkeeping are among the biggest causes of tax issues. Why it matters: It can lead to incorrect BAS lodgements
You might miss out on deductions
Poor records increase the chance of an ATO review or audit
A simple solution: Use cloud accounting tools like QuickBooks or Xero, and save digital copies of receipts and invoices. Good records = fewer headaches.
- Misunderstanding GST Obligations
Not everyone is clear about when they need to register for GST or how GST should be reported. Common mistakes we see: Not registering once your turnover reaches $75,000
Claiming GST credits without valid tax invoices
Charging GST when you’re not registered
Incorrectly reporting GST-free or input-taxed sales
How to stay compliant: Review your GST requirements regularly and double-check your BAS before lodging.
- Incorrectly Claiming Deductions
It’s easy to overclaim or underclaim if you’re unsure about what counts as a business expense. Common issues include: Claiming personal expenses as business use
Overstating car or home office deductions
Forgetting to depreciate assets
Not keeping proper logbooks for work-related travel
To avoid mistakes: Track business use properly and follow ATO guidelines on what is and isn’t deductible.
- Forgetting to Pay Superannuation on Time
The Super Guarantee (currently 11%) must be paid correctly and on time. Many business owners don’t realise that late super payments aren’t tax-deductible. If paid late: You lose the tax deduction
Additional ATO fees apply
Your business may face compliance issues
The fix: Use payroll software or reminders to make sure super is paid before the due dates.
- Missing ATO Deadlines
BAS, IAS, tax returns, and super deadlines can pile up fast. Missing them can lead to interest charges or penalties. Why deadlines get missed: You’re busy running the business
There’s no proper system in place
You don’t have an accountant keeping track
A reliable solution: Engage a registered tax agent. They will manage deadlines, keep you compliant, and prevent unnecessary penalties.
- Trying to Handle Everything Yourself
It’s common for small business owners to try to save money by doing all the bookkeeping and tax work themselves. But DIY accounting often leads to costly mistakes. Risks include: Incorrect BAS lodgements
Missed deductions
Overpaying tax
Compliance breaches
A better approach: Work with an accounting firm that understands your business and can keep your books accurate throughout the year.
Final Thoughts Avoiding tax mistakes isn’t just about following the rules — it’s about protecting your business, improving cash flow, and reducing unnecessary stress. With the right support, you can stay compliant, claim everything you’re entitled to, and plan ahead with confidence. At S&S Accounting and Business Services, we help small businesses stay on top of their obligations, maximise deductions, and keep their finances running smoothly. Whether you need help with BAS lodgement, payroll, bookkeeping, or tax planning, we’re here to support your business every step of the way.