A Business Activity Statement (BAS) is the form you send the ATO to report and pay the GST you have collected, minus the GST you have paid on business purchases. If you are registered for GST you have to lodge one — usually every quarter — whether or not you traded that period. It is a reporting obligation, not a bill that only arrives when you owe something.
Who has to lodge a BAS?
Anyone registered for GST. Registration becomes compulsory once your GST turnover reaches $75,000 in a rolling twelve-month period — that is not the financial year, it is any twelve months. Non-profit organisations have a $150,000 threshold, and anyone driving for a ride-sourcing or taxi service must register from their first dollar regardless of turnover.
Below the threshold, registering is optional. Some sole traders register voluntarily so they can claim back the GST on their tools and materials; others stay out of it to avoid the paperwork. If you are not registered you do not lodge a BAS at all.
What goes on the form
For a simple sole trader, most of the BAS is blank. These are the labels that matter:
| Label | What it reports |
|---|---|
| G1 | Total sales for the period, including any GST you charged. |
| G3 | The portion of those sales that were GST-free. |
| 1A | GST on sales — the GST you collected and owe the ATO. |
| 1B | GST on purchases — the GST you paid and can claim back. |
You owe the ATO the difference between 1A and 1B. If 1B is larger — you spent more on GST than you collected, which happens in a quarter where you bought a vehicle or a lot of stock — the ATO refunds you.
When is a BAS due?
Most small businesses report quarterly. The standard due dates are:
| Quarter | Standard due date |
|---|---|
| July – September | 28 October |
| October – December | 28 February |
| January – March | 28 April |
| April – June | 28 July |
Lodging through a registered BAS or tax agent generally earns you extra time. Businesses turning over $20 million or more report monthly, and some very small businesses can report annually — the ATO tells you which cycle you are on when you register.
Cash or accruals?
On a cash basis you report GST in the quarter the money actually moves. On an accruals basis you report it in the quarter you issued the invoice, even if the client has not paid. Most small businesses choose cash, because it means never remitting GST on money you have not received. Eligibility depends on your turnover.
What goes wrong most often
- Claiming GST that was never charged. If a supplier is not registered, there is no GST on their invoice to claim at 1B.
- Claiming GST on GST-free purchases. Most basic food, and many health and education services, carry no GST.
- Reverse-calculating wrongly. The GST inside a $1,100 total is $100, not $110. Divide by 11, do not take 10% off — the GST calculator handles it.
- Claiming the private portion. For something used partly privately, you can only claim the business-use share.
- Not lodging a nil BAS. A quarter with no activity still needs a statement lodged, showing zeros.
Making it a copy-across instead of a weekend
The work in a BAS is not the form — it is reconstructing three months of GST from a folder of receipts. Software that tags the GST treatment on each invoice and expense as you enter it means the quarterly totals are already there. Balaana does that on the free plan, and lays the figures out against these labels.
Balaana does not lodge for you. You or your registered agent do that, through Online services for business, myGov or your agent's software.
Related reading
- Do I need to register for GST? — the step before any of this applies
- How to invoice with GST — getting 1A right at the source
- Sole trader tax deductions — the income tax side
- GST calculator — add or remove GST correctly
- Cash vs accrual accounting — the choice behind which quarter a sale lands in
- PAYG instalments — the other section of the same form
Frequently asked questions
Yes. If you are registered for GST you lodge for every period, even a quarter with no activity. It is called a nil BAS and it reports zeros. Not lodging attracts a failure to lodge penalty regardless of whether you owed anything.
A BAS reports GST (and PAYG if you have employees) and is usually lodged quarterly. An income tax return reports your income and deductions for the whole financial year and is lodged annually. They are separate obligations and lodging one does not cover the other.
Yes. You can lodge through ATO Online services for business, or through myGov if you are a sole trader. You can also use a registered BAS or tax agent, who generally gets a later due date.
The ATO can apply a failure to lodge on time penalty, calculated in penalty units for each 28-day period the statement is late, and interest accrues on unpaid amounts. If you are struggling, contacting the ATO before the due date generally goes better than going quiet.
No, and many sole traders lodge their own. What matters is that the underlying records are right — the form itself is short. If your affairs are more complicated than invoices and expenses, a registered BAS agent is worth the fee.
Sources
Thresholds, labels and due dates in this article come from the Australian Taxation Office. Rates and dates change — confirm the current position at ato.gov.au or with a registered tax agent. This article is general information, not personal tax advice.