BAS common mistakes Australia: Avoid penalties and late lodgment fees
What Is BAS (And Why It Matters)
A Business Activity Statement (BAS) is your tax and GST report.
You lodge it quarterly (every 3 months). You report:
- GST collected (if registered)
- GST paid on purchases
- PAYG tax withheld from employees
- Company tax installments
Missing the deadline or getting figures wrong = penalties.
The Penalties (They Add Up Fast)
Late lodgment:
- 1 penalty unit ($330) per 28 days late
- Late by 1 month? $330 penalty
- Late by 3 months? $990 penalty
- Late by 12 months? $3,960 penalty
Incorrect BAS:
- Up to $33,600 penalty
- Plus, interest on unpaid tax
- Plus amending future BAS forms
Non-lodgment (never submitted):
- Up to $66,000 penalty
- Criminal prosecution possible
One mistake = compounding costs.
Mistake 1: Wrong GST Figures
You report GST collected incorrectly.
Example:
- You collected $50,000 GST from customers
- You report $45,000 (error)
- ATO asks for $5,000 + interest + penalties
Why it happens:
- Invoicing software doesn’t sync with accounting software
- Manual entry error
- Not accounting for credit notes or adjustments
How to avoid:
- Print GST report from accounting software
- Reconcile to bank deposits
- Match to invoices issued
- Check for credit notes and returns
Mistake 2: Missing Deadline (28 Days Late = First Penalty)
BAS is due 28 days after quarter end.
Example:
- Quarter ends 30 Sept
- BAS due: 28 Oct
- You lodge: 3 Nov (6 days late)
- Penalty: 1 unit ($330)
Most businesses don’t realize the deadline is tight.
How to avoid:
- Set calendar reminder for 21 days after quarter end (1 week buffer)
- Mark deadline in your accounting software
- Allocate 2-3 hours before deadline to prepare BAS
Mistake 3: Mixing Up PAYG Withholding
You withhold tax from employee wages. You report it on BAS.
Common errors:
- Forgot to update tax tables when rates changed
- Withheld wrong amount
- Didn’t withhold at all (casual only)
- Included contractor payments (shouldn’t be withheld)
Example:
- You didn’t update tax tables for July 2025 income tax cuts
- You withheld $200/week when should be $180/week
- Overpaid tax on BAS
- ATO adjusts and asks for explanation
How to avoid:
- Update tax tables whenever ATO announces changes
- Run monthly payroll audit (spot-check 3 pay slips)
- Compare withholding rates to ATO tables
Mistake 4: No Supporting Records
ATO asks for evidence. You have none.
Example:
- You claim $10,000 in GST credits (purchases)
- ATO asks for invoices
- You can’t find them
- ATO disallows the credit
- You owe back GST + interest + penalty
How to avoid:
- Keep all invoices (digital or paper) for 5 years
- Match invoices to GST claims
- Use accounting software that stores attachments
- Monthly: Reconcile GST claims to invoices
Mistake 5: Lodging BAS When Unregistered (Or Not Lodging When Registered)
Mistake A: You’re GST-registered but think you’re not.
- You lodge GST as $0
- ATO notices discrepancy
- Penalties apply
Mistake B: You’re NOT GST-registered but lodge BAS anyway.
- BAS is for registered businesses only
- Filing without registration looks wrong
- ATO questions your status
How to avoid:
- Check your ABN on the ABR website
- Confirm GST registration status
- If uncertain, contact ATO or accountant
The 5-Step BAS Preparation Checklist
3 weeks before deadline:
- Set aside 2-3 hours to prepare BAS
- Gather all invoices and tax records
- Reconcile GST collected to bank deposits
- Reconcile GST paid to supplier invoices
2 weeks before deadline:
- Pull PAYG withholding from payroll
- Check tax tables are current
- Calculate company tax installment (if applicable)
1 week before deadline:
- Enter all figures into BAS
- Double-check calculations
- Review for obvious errors
- Print BAS for review
Before lodgment:
- Verify ABN and business name
- Confirm lodgment method (online, accountant)
- Lodge 5 days before deadline (buffer)
If you’re unsure: Have an accountant lodge it.
What Happens If You Miss the Deadline
Day 1–28 late: No penalty yet Day 28: First penalty issued ($330) Day 56: Second penalty ($330) Day 84: Third penalty ($330)
Penalties keep accruing until you lodge.
One quarter missed = $990 in penalties (minimum).
Get Help
BAS lodgment is complex. Mistakes are expensive.
In Campbelltown and Greater Sydney, we prepare and lodge BAS for small businesses.
📞 Call: 04 044 71 816
We’ll prepare your BAS, ensure on-time lodgment, and avoid penalties.
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