What Is a BAS Statement? Business Activity Statements Explained

Short answer: A BAS statement, or business activity statement, is the form a GST-registered business lodges with the ATO to report and pay GST, PAYG instalments, PAYG withholding and some other taxes. Most sole traders lodge one every quarter, due 28 October, 28 February, 28 April and 28 July. On it you report your total sales (G1), the GST on those sales (1A) and the GST on your purchases (1B), then pay the difference plus any instalment. You have to lodge even when there’s nothing to report.

The business activity statement is run by the Australian Taxation Office. This guide explains it for a sole trader in the 2026–27 income year (1 July 2026 – 30 June 2027), the year whose first quarterly BAS is due on 28 October 2026. It covers what a BAS is and what goes on one. For the mechanics of filling one in, label by label, see how to do a BAS. For a full calendar, see BAS due dates.

What is a BAS?

A BAS is the ATO form businesses use to report and pay their GST and their pay-as-you-go (PAYG) amounts for a period. BAS stands for business activity statement, so “BAS statement” says “statement” twice. Everyone uses the phrase anyway, and it means the same thing.

It isn’t a tax return. A BAS covers shorter periods and mostly deals with money that was never yours: GST collected from customers and tax withheld from other people’s pay. It also carries any PAYG instalments, which are prepayments towards your own income tax. When you register for an ABN and GST, the ATO sends you a BAS automatically when it’s time to lodge.

Who has to lodge a BAS?

Every business registered for GST lodges a BAS, sole traders included. You become one of them once your GST turnover reaches $75,000, or earlier if you register voluntarily. Ride-sourcing drivers register from their first trip.

• Registered for GST: you lodge a BAS for every period. If nothing happened in a quarter, you still lodge it as a “nil” BAS by the due date.
• Not registered for GST, but paying PAYG instalments: you report and pay instalments through an activity statement or an instalment notice. You don’t lodge a full BAS for GST.
• Not registered for GST, no instalments, no employees: there’s nothing to lodge. You report your business income once a year on your tax return. Sole trader taxes covers that side.

What does a BAS statement report?

A BAS reports GST, PAYG instalments and PAYG withholding. Small businesses with GST turnover under $10 million use Simpler BAS by default, which cuts the GST section down to three labels.

Label	What goes there	Who fills it in
G1	Total sales for the period. The form asks whether the figure includes GST	Everyone registered for GST
1A	GST on sales, or a GST instalment amount	Everyone registered for GST
1B	GST on purchases, meaning the GST credits you’re claiming	Everyone registered for GST
W1	Total salary, wages and other payments	Only if you pay employees
W2	Tax withheld from the payments at W1	Only if you pay employees
4	Total amounts withheld, carried to the summary	Only if you withhold
T7	PAYG instalment amount	Only if you’re in PAYG instalments
5A	PAYG income tax instalment, copied from T7	Only if you’re in PAYG instalments

Businesses with GST turnover of $10 million or more use full reporting, which adds export sales, other GST-free sales and capital and non-capital purchases. A sole trader almost never needs those.

The summary section adds up what you owe the ATO, including 1A, 4 and 5A, and takes off what the ATO owes you, including 1B. The result is a single amount to pay or to get back.

What does a BAS statement look like in practice?

Here’s a quarterly BAS for a sole trader electrician for July to September 2026. They’re registered for GST, account for GST on a cash basis, have no employees and have received a PAYG instalment amount from the ATO.

Label	Amount	Where it comes from
G1 Total sales	$27,500	Payments received this quarter, GST included
1A GST on sales	$2,500	$27,500 ÷ 11
1B GST on purchases	$640	$7,040 of business purchases with GST, ÷ 11
T7 / 5A PAYG instalment	$1,800	The amount the ATO worked out
W1, W2, 4	—	No employees
Amount payable	$3,660	$2,500 + $1,800 − $640

The electrician lodges and pays $3,660 by 28 October 2026. Of that, $1,860 is GST, which belonged to customers all along. The other $1,800 is income tax paid early, and it’s credited against their 2026–27 tax bill when they lodge their return. How to calculate GST explains the divide-by-11 step. If they used accruals instead, G1 would count sales invoiced in the quarter, or paid in it if payment came first, whether or not the money had arrived.

How often do you lodge a BAS: monthly, quarterly or annually?

Most sole traders lodge quarterly. How often you lodge depends on your GST turnover and, in some cases, on what you choose.

Frequency	Who it applies to	When it’s due
Monthly	Required if GST turnover is $20 million or more, or if the ATO tells you to. Anyone else can choose it	21st of the following month
Quarterly	GST turnover under $20 million: the default	28th of the month after the quarter (28 February for Oct–Dec)
Annually (GST only)	You’re voluntarily registered and GST turnover is under $75,000	31 October, or 28 February if you don’t have to lodge a tax return

Annual GST reporting is only for voluntary registrants, and ride-sourcing drivers can’t choose it. There’s also a middle option, GST instalments. You pay a fixed quarterly amount that the ATO works out from your past GST, then report your actual figures once a year on an annual GST return.

When is a BAS due?

A quarterly BAS is due on the 28th of the month after the quarter ends. October to December is the exception: it gets an extra month, to 28 February.

Quarter (2026–27)	Period	Lodge and pay by
Q1	July – September 2026	28 October 2026
Q2	October – December 2026	28 February 2027
Q3	January – March 2027	28 April 2027
Q4	April – June 2027	28 July 2027

If you lodge online, you may be eligible for an extra two weeks on each quarter except Q2, whose due date already includes its one-month extension. A registered tax or BAS agent may get you more time again. Payment is due on the same date as lodgment, not afterwards. BAS due dates covers the agent dates and what happens when a due date falls on a weekend.

How do you lodge and pay a BAS?

Most sole traders lodge through the ATO’s online services for individuals and sole traders, which you get to through myGov. The other route is a registered tax or BAS agent, who lodges for you.

• Online: open the BAS, enter the labels, check the summary and lodge. For a nil BAS, choose “Prepare”, then “Prepare as nil”.
• By phone, for a nil BAS: the ATO has an automated nil lodgment line, 13 72 26, available 24 hours a day.
• Pay by the due date: lodging without paying still leaves the debt open, and interest can apply.
• Fix mistakes: you can revise an earlier BAS, and some errors can be corrected on a later one.

Your accounting method decides which BAS a sale belongs on. With a cash basis, which is open to businesses with aggregated turnover under $10 million, GST goes on the BAS for the period you’re paid. On a non-cash (accruals) basis it goes on the BAS for the period you issue the invoice or receive payment, whichever comes first. That’s why the date on your invoices matters. See how to invoice as a sole trader.

What sits behind each BAS figure, and where does Keel fit?

Every number on a BAS has to trace back to a document. G1 and 1A come from your invoices and the payments you received. 1B comes from tax invoices and receipts for things you bought.

Keel: Invoice Maker & Receipts, by Ilura Technology OÜ, is an iPhone app for keeping those documents. You write estimates, and an accepted estimate becomes the invoice in one tap. Each invoice is a PDF, and receipts and expenses are filed under the job they belong to. You can log business mileage, and a “who owes you” list drafts payment reminders that you review and send yourself. Records stay on your iPhone: there’s no account, no bank connection and no cloud sync, and the App Store privacy label reads “Data Not Collected”.

To be clear, Keel doesn’t prepare or lodge a BAS, doesn’t connect to the ATO and doesn’t calculate what you owe. You or your BAS agent still do that from the records. It’s free with no invoice limit, and free invoices carry a small “Made with Keel” footer. Keel Lifetime is a one-time purchase ($249.99 USD; the App Store shows your local price) that adds custom branding, a signature, premium templates and accountant-ready exports. Keel on the App Store. There’s more in the Australia guides.

Frequently asked questions

What does BAS stand for? BAS stands for business activity statement. It’s the form businesses registered for GST lodge with the Australian Taxation Office to report and pay GST, PAYG instalments, PAYG withholding and some other taxes. “BAS statement” repeats the word “statement”, but it’s the common name for the same form, and the ATO sends one to you automatically when it’s due.

Do I need to lodge a BAS if I am not registered for GST? Usually not. A full BAS is for businesses registered for GST. If you aren’t registered, but the ATO has put you into PAYG instalments, you report and pay those through an activity statement or an instalment notice. If you pay employees, the tax you withhold is reported through your activity statement. Otherwise your business income goes on your annual tax return.

What is a nil BAS? A nil BAS is a business activity statement with nothing to report: no sales, no purchases and no withholding for the period. You still have to lodge it by the due date, because the ATO is expecting it. You can lodge a nil BAS online by choosing “Prepare as nil”, or through the ATO’s automated phone line on 13 72 26.

Is a BAS the same as a tax return? No. A BAS covers a month, a quarter or a year of GST and PAYG amounts, most of which is money you collected or withheld on the government’s behalf. Your income tax return is lodged once a year and works out the tax on your profit. PAYG instalments paid through your BAS are credited against the tax on that return.

Can I do my own BAS as a sole trader? Yes. Most sole traders can lodge their own BAS through the ATO’s online services for individuals and sole traders, which you reach through myGov. Under Simpler BAS you only report G1, 1A and 1B for GST, plus any PAYG amounts. A registered tax or BAS agent can lodge it for you instead, and agents may have later due dates.

Does cash or accrual accounting change my BAS? It changes which BAS a sale or purchase lands on. On a cash basis, which is available if your aggregated turnover is under $10 million, you report GST for the period you’re paid or you pay. On a non-cash (accruals) basis you report it in the period you issue the invoice or receive payment, whichever comes first, even if the client hasn’t paid yet.

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This article is general information, not tax advice. Consult a qualified Australian tax professional.