Every quarter, your finance team drops everything to prepare BAS. They chase missing receipts, reconcile GST on hundreds of transactions, and hope the numbers add up before the deadline. For most Australian SMEs, BAS preparation is the single most stressful compliance task on the calendar.
It doesn’t have to be. This guide explains what BAS is, who needs to lodge, when it’s due, and the common mistakes that cost businesses money. At the end, you’ll find a practical checklist you can use for your next lodgement.
What is BAS?
A Business Activity Statement (BAS) is a form submitted to the Australian Taxation Office (ATO) that reports your business’s tax obligations. It covers GST collected and paid, PAYG withholding from employee wages, PAYG instalments, and other taxes like fuel tax credits or luxury car tax.
If your business is registered for GST, you lodge a BAS regularly. The ATO uses it to calculate whether you owe GST or are entitled to a refund.
Who needs to lodge a BAS?
You must lodge a BAS if:
- Your business is registered for GST
- Your annual turnover is $75,000 or more ($150,000 for not-for-profits)
- You operate as a company, sole trader, partnership, or trust that meets GST thresholds
If you’re not registered for GST, you don’t need to submit a BAS. But you still have other tax reporting obligations.
When is a BAS due?
The ATO assigns a reporting frequency based on your turnover:
| Frequency | Who | Due dates |
|---|---|---|
| Quarterly (most businesses) | Turnover under $20 million | 28 Oct, 28 Feb, 28 Apr, 28 Jul |
| Monthly | Turnover over $20 million | 21st of each month |
| Annually | Voluntarily registered for GST | 31 Oct (same as tax return) |
Late lodgement attracts penalties and interest charges. If you use a registered BAS agent, you may get an extended deadline.
What does a BAS include?
GST (Goods and Services Tax)
The core of most BAS lodgements. You report:
- GST collected from sales (output tax)
- GST paid on business expenses (input tax credits)
- The net amount owed to the ATO, or refundable to you
PAYG withholding
Tax withheld from employee wages before paying salaries. You report the total amount withheld during the period.
PAYG instalments
Estimated income tax payments for businesses required to pay in advance. The ATO calculates the amount based on your most recent tax return.
Other taxes
Depending on your business, you may also report fuel tax credits, luxury car tax, wine equalisation tax, or fringe benefits tax instalments.
Common BAS mistakes that cost money
1. Missing GST credits because receipts are lost
Without a valid tax invoice, you cannot claim the GST input credit. Every lost receipt is money left on the table. Across hundreds of transactions per quarter, this adds up fast.
2. Claiming GST on GST-free items
Not everything attracts GST. Basic food, some medical services, and certain education courses are GST-free. Claiming credits on these items triggers ATO scrutiny.
3. Under-reporting PAYG withholding
If the PAYG amounts on your BAS don’t match your payroll records, the ATO will notice. Reconcile payroll before lodging.
4. Lodging late
The penalty for late lodgement starts at one penalty unit ($313 in 2025-26) for each 28-day period the BAS is overdue, up to a maximum of five penalty units. For a quarterly BAS that’s three months late, that’s nearly $1,000 in penalties alone.
5. Mixing personal and business expenses
Shared cards and reimbursement claims make it hard to separate personal from business spending. If personal expenses end up on your BAS, you’re overclaiming GST credits.
BAS preparation checklist
Use this before every lodgement:
- Reconcile all bank accounts for the period
- Verify every transaction has a valid tax invoice or receipt attached
- Confirm GST codes are correct on all transactions (taxable, GST-free, input-taxed)
- Reconcile PAYG withholding against payroll records
- Check for any outstanding reimbursement claims that need processing
- Review supplier invoices for correct ABN and GST amounts
- Run a BAS preview report in your accounting software before lodging
- Not sure how much you’ll owe? Use our free BAS calculator to estimate your GST liability before lodging
- Confirm the reporting period matches the ATO’s assigned frequency
- Lodge via the ATO Business Portal, your accounting software, or your BAS agent
- Record the lodgement date and any payment due
How to lodge your BAS
Four options, from most to least common:
1. Through your accounting software. Xero, MYOB, and QuickBooks can generate and submit your BAS directly to the ATO. This is the fastest method if your data is clean.
2. Online via the ATO Business Portal. Log in with your myGov account and lodge directly. Good for simple BAS lodgements.
3. Through a registered BAS or tax agent. Your accountant or bookkeeper can prepare and lodge on your behalf. They may also get extended deadlines.
4. By mail. Paper BAS forms can be posted to the ATO. This is the slowest option and not recommended.
The real problem: getting clean data into your BAS
Most BAS stress isn’t about the form itself. It’s about the data that feeds it.
When your team uses shared bank cards, processes reimbursements manually, or chases paper receipts at month-end, the data going into your BAS is incomplete. Missing receipts mean missed GST credits. Uncategorised transactions mean manual coding. Late expense claims mean last-minute adjustments.
The businesses that find BAS painless are the ones that solved the data problem upstream. Their transactions are coded in real time. Receipts are captured at point of sale. GST is tracked automatically on every purchase.
That’s what Budgetly’s expense management platform does. Every employee gets a pre-approved Visa debit card with spending controls. When they make a purchase, the mobile app prompts for a receipt photo immediately. AI Bookkeeping reads, checks, and codes the transaction. By the time BAS is due, your data is already clean.
The result: BAS preparation goes from days of chasing to minutes of verification.
“It used to take us a full day to do credit card reconciliation, and hours to process reimbursements. With Budgetly, it takes half an hour a week.”
Adam Shnider, Head of Finance, Carer Solutions
