Tax & ATO
Business Activity Statement
A Business Activity Statement (BAS) is the ATO form GST-registered Australian businesses lodge, usually quarterly, to report and pay GST, PAYG withholding from employee wages, PAYG instalments and certain other taxes. Quarterly BAS is generally due 28 days after the quarter ends; lodging through a registered agent usually extends the deadline.
The BAS pulls several obligations into one lodgement. The GST section reports your total sales at label G1, GST collected on sales at label 1A, and GST credits on purchases at label 1B; the difference is what you pay or get refunded. If you employ staff, the PAYG withholding section reports gross wages at W1 and the tax you withheld at W2. If the ATO has put you into the PAYG instalments system, your quarterly prepayment of income tax appears here too, and businesses with fringe benefits or fuel tax credit claims report those on the same form.
Which sections appear depends on your registrations, which is why no two businesses' statements look identical. Good bookkeeping makes the BAS an output rather than a project: if sales and purchases are coded with the right GST treatment through the quarter, labels G1, 1A and 1B are already sitting in your software. The ATO's guide to business activity statements on ato.gov.au explains each label. Businesses not registered for GST report PAYG obligations on the simpler Instalment Activity Statement (IAS) instead.
Most small businesses lodge quarterly. Businesses with GST turnover of $20 million or more must lodge monthly, and very small businesses can elect annual GST reporting in limited cases. Quarterly due dates fall 28 days after quarter end, with a built-in extension for the December quarter to allow for the holiday period.
| Quarter | Period covered | Standard due date |
|---|---|---|
| Q1 | July to September | 28 October |
| Q2 | October to December | 28 February |
| Q3 | January to March | 28 April |
| Q4 | April to June | 28 July |
Lodging electronically through a registered tax agent or BAS agent generally adds about four weeks to the Q1, Q3 and Q4 deadlines (the February date already includes its extension). Monthly BAS is due on the 21st of the following month. When a due date falls on a weekend or public holiday, you can lodge and pay on the next business day.
The BAS is the most frequent compliance deadline most Australian small businesses face, and missing it has two costs: a failure-to-lodge penalty (calculated in penalty units per 28 days late) and general interest charge on any unpaid amount. Since the ATO data-matches BAS figures against Single Touch Payroll, TPAR and bank data, a statement that does not line up with your other reporting invites questions.
The practical risk is rarely the form itself; it is cash. GST collected and tax withheld from wages were never your money, so the businesses that find BAS time painless are the ones that park roughly one-eleventh of GST-inclusive sales plus each pay run's withholding in a separate account. A worked quarter: you invoice $99,000 GST-inclusive (1A = $9,000), your purchases include $3,200 of GST (1B = $3,200), and you withheld $5,400 from wages (W2). Your BAS payment is $9,000 - $3,200 + $5,400 = $11,200. Estimate your own quarter with the OneBookPlus BAS calculator before the due date so the amount is never a surprise.
The definitions above only get you so far; the free OneBookPlus BAS calculator turns them into your own figures in seconds, no sign-up needed.
Yes. A registered business must lodge every BAS on time even when the answer is zero. Nil statements can be lodged quickly online or by phone. Not lodging at all triggers failure-to-lodge penalties, even when no tax was payable.
A BAS is for GST-registered businesses and includes GST labels. An Instalment Activity Statement (IAS) is the simpler form used by taxpayers who are not registered for GST, or by employers who withhold monthly between their quarterly BAS lodgements, to report PAYG withholding and instalments.
Lodging electronically through a registered tax agent or BAS agent generally extends quarterly due dates by around four weeks, except the December quarter which is already extended to 28 February. If a due date falls on a weekend or public holiday, the next business day applies.
Last reviewed and updated: by Bishal Shrestha