What Is a BAS? The Business Activity Statement Explained
What is a BAS? The short answer
A BAS, or Business Activity Statement, is the form a GST-registered business uses to report and pay several taxes to the Australian Taxation Office on one document: the GST you collected on sales and the GST credits you claim on purchases, any PAYG tax you withheld from employees, and your PAYG income tax instalments. The ATO sends you a BAS automatically once you register for GST. Most small businesses lodge one each quarter.
This guide explains what each part of a BAS reports, who has to lodge one, how a BAS differs from an instalment activity statement, and the ways you can lodge yours.
What a BAS reports
People think of the BAS as "the GST form", and GST is the biggest part of it for most small businesses. But the activity statement is really a single return for several separate obligations, so you only fill in the parts that apply to you. The ATO uses it to collect:
- GST. The GST you charged on sales, less the GST credits you claim on business purchases. If you charged more than you can claim, you pay the difference; if you claimed more, the ATO refunds you.
- PAYG withholding. If you employ staff, the tax you held back from their wages and now send to the ATO.
- PAYG income tax instalments. Pre-payments towards your own income tax for the year, so you are not left with one large bill after you lodge your return. The mechanics of these are covered in our guide to PAYG instalments.
- Other taxes where they apply. Fuel tax credits, fringe benefits tax instalments, luxury car tax and wine equalisation tax each have their own labels for the businesses that deal with them.
A sole trader with no employees and no instalment obligation might have a BAS that only reports GST. A larger business can have all of it on the one statement. The due dates for each cycle are a separate topic, set out in our guide to BAS due dates.
Who lodges a BAS, and who gets an IAS instead
The trigger for a BAS is GST registration. You must register for GST once your GST turnover reaches $75,000 ($150,000 for a not-for-profit), and you have 21 days to do it once you cross the line. You register against your ABN. From then on the ATO issues you a BAS for each reporting period, and you report and pay your GST through it.
If you are not registered for GST but still have PAYG obligations, you report on a different form: an Instalment Activity Statement, or IAS. The IAS carries PAYG withholding and PAYG instalments but no GST. This is the form a business below the $75,000 threshold uses when it has employees, and the form some individuals receive purely for their income tax instalments.
| BAS | IAS | |
|---|---|---|
| Who gets it | Businesses registered for GST | Businesses and individuals with PAYG obligations but no GST registration |
| Reports GST | Yes | No |
| Reports PAYG withholding | Yes | Yes |
| Reports PAYG instalments | Yes | Yes |
There is a third case. If you pay a quarterly GST or PAYG instalment using the amount the ATO works out for you, and you have nothing else to report, you may receive a quarterly instalment notice rather than a statement to fill in. You can pay the amount shown without lodging anything.
The main labels on a BAS
The BAS is a grid of labelled boxes, and you leave most of them blank. These are the ones a typical small business fills in.
| Label | What it reports |
|---|---|
| G1 | Total sales for the period (you tick whether the figure includes GST) |
| 1A | GST you collected on those sales |
| 1B | GST credits you are claiming on purchases |
| W1 | Total wages and salary you paid that are subject to withholding |
| W2 | Tax you withheld from those wages |
| 5A | Your PAYG income tax instalment for the period |
GST in Australia is 10%, but on a GST-inclusive figure it works out to one-eleventh, not one-tenth. Say a sole trader's quarter looks like this: $33,000 in sales (GST included) and $11,000 of purchases that carried GST. The GST on sales at 1A is $33,000 ÷ 11 = $3,000. The GST credits at 1B are $11,000 ÷ 11 = $1,000. The net GST payable with that BAS is $3,000 − $1,000 = $2,000, and G1 shows the full $33,000 of sales. The GST credits at 1B are only valid where you hold a tax invoice for purchases over $82.50 including GST.
If you report through Single Touch Payroll, the ATO pre-fills W1 and W2 for you from your payroll data, though you should still check them against your own records. The PAYG instalment at 5A is either the dollar figure the ATO gives you (its Option 1) or a figure you work out from your actual income for the quarter (Option 2), as explained in the PAYG instalments guide.
Simpler BAS vs the full reporting method
How much GST detail you report depends on your size. Since 2017 the ATO's default for a business with a GST turnover under $10 million is Simpler BAS: you report only the three GST labels above (G1, 1A and 1B) and skip the GST calculation worksheet entirely. This covers almost every sole trader and small business.
A business with a GST turnover of $10 million or more uses the full reporting method, which adds labels for export sales (G2), other GST-free sales (G3), capital purchases (G10) and non-capital purchases (G11). The underlying GST you pay is the same; the full method just asks you to break the figures down further.
Your reporting cycle is a separate question from your method. The ATO puts you on monthly reporting if your GST turnover is $20 million or more, quarterly if it is under $20 million (the default for most small businesses), and annually only where you registered for GST voluntarily and your turnover stays under $75,000.
How to lodge your BAS, and what a nil BAS is
You can lodge your BAS through any of these channels:
- Online services for business, signing in with your myID linked to your business through Relationship Authorisation Manager.
- ATO online services through myGov, if you are a sole trader. You reach the activity statement under the Tax and Lodgments menus.
- A registered tax or BAS agent, who lodges on your behalf and may qualify for later due dates under the agent lodgment program.
- SBR-enabled accounting software that connects to the ATO directly.
A quarter with no sales and no expenses does not let you off. If you are registered for GST you still have to lodge, and you lodge a nil BAS: in the online form you choose "Prepare as nil" instead of entering figures. You can also lodge a nil statement through the ATO's automated phone service on 13 72 26, which runs 24 hours a day. Skipping a nil BAS is treated as a late lodgment, with the same failure-to-lodge penalty as any other missed statement.
How SparkReceipt keeps your BAS figures ready
A BAS is only as quick as your records. The slow part is not the form, it is reconstructing three months of GST on sales and purchases when the quarter has already closed. SparkReceipt reads a photographed or emailed receipt and pulls out the vendor, date, total and the GST amount, applying Australian GST treatment, then files each one as a categorised expense. Because the GST is captured on every document as you go, the figure behind label 1B is a running total rather than a shoebox you sort out in late October.
When you upload a bank or card statement, SparkReceipt extracts every transaction and matches it against your receipts, so you can see which purchases still lack a tax invoice before you claim the credit. At BAS time you export a report with GST-aware category totals for your records or your accountant. SparkReceipt does not lodge the activity statement for you, and it does not replace a BAS agent; it keeps the numbers you put on the BAS organised and backed by the original documents. See pricing for plan details, including the free accountant seat.
Frequently asked questions
What does BAS stand for? BAS stands for Business Activity Statement. It is the form a GST-registered business uses to report GST and, where they apply, PAYG withholding, PAYG instalments and a few other taxes to the ATO on one document.
Do I need to lodge a BAS if I am not registered for GST? No. A BAS is tied to GST registration. If you are not registered for GST you will not receive a BAS, though you may receive an instalment activity statement (IAS) if you have PAYG withholding or PAYG instalment obligations.
How often do I have to lodge a BAS? Most small businesses lodge quarterly. The ATO moves you to monthly reporting if your GST turnover is $20 million or more, and allows annual reporting only if you registered for GST voluntarily and stay under the $75,000 turnover threshold.
Do I still lodge a BAS if I had no income this quarter? Yes. If you are registered for GST you lodge a nil BAS by choosing "Prepare as nil" in the online form, or by phoning the ATO's automated service. Not lodging is treated as a late lodgment.
What is the difference between a BAS and an IAS? A BAS reports GST plus any PAYG obligations and is issued to GST-registered businesses. An IAS reports PAYG withholding or PAYG instalments only, with no GST, and goes to taxpayers who are not registered for GST.
Can I lodge my own BAS, or do I need an agent? You can lodge your own BAS through Online services for business, myGov, or accounting software. A registered BAS or tax agent is optional, though using one can give you later due dates under the agent lodgment program.
Key takeaways
- A BAS (Business Activity Statement) is the one form a GST-registered business uses to report GST, PAYG withholding, PAYG instalments and some other taxes to the ATO.
- The $75,000 GST turnover threshold is what triggers a BAS; below it, a business with PAYG obligations reports on an IAS instead, which carries no GST.
- Most small businesses use Simpler BAS and report just three GST labels: G1 total sales, 1A GST on sales, and 1B GST credits on purchases.
- GST on a GST-inclusive amount is one-eleventh of the figure, so $33,000 of sales carries $3,000 of GST at 1A.
- A quarter with no activity still needs a nil BAS; skipping it draws the same failure-to-lodge penalty as any other late statement.