Work out this quarter's GST
Enter GST-inclusive figures — what you actually invoiced and what you actually paid.
Everything you invoiced this period, GST inclusive.
Materials, tools, fuel and subbies — GST inclusive. Leave out wages and anything GST-free.
Tax withheld from employee wages this period. Zero if you have no staff.
Net GST to pay the ATO
$5,000
GST for the period
$88,000
G1 total sales
$8,000
1A GST on sales
$3,000
1B GST on purchases
$5,000
total including PAYG withheld
Prices are GST inclusive in Australia, so the GST inside a figure is the figure ÷ 11 — not 10% of it. $88,000 of sales carries $8,000 of GST, not $8,800. Due 28 October, 28 February, 28 April and 28 July. An estimate to check your figures against, not a lodgment.
Divide by 11, not by 10
Australian prices are quoted GST inclusive, so the GST already sits inside the number on the invoice. To pull it back out you divide by 11 — an $11,000 job contains $1,000 of GST.
Taking 10% of a GST-inclusive total gives $1,100, which is 10% too much, and it compounds across a whole quarter. The rule is simple once you see it: 10% going on, one-eleventh coming back off.
Quarterly due dates
Standard dates for self-lodgment. A registered BAS or tax agent generally gets you a later concessional date.
| Quarter | Due |
|---|---|
| July – September | 28 October |
| October – December | 28 February |
| January – March | 28 April |
| April – June | 28 July |
The three labels that matter
G1 — Total sales
Everything you invoiced for the period, GST inclusive. Not profit, not what has been paid yet — what you billed.
1A — GST on sales
The GST inside G1, so G1 ÷ 11. This is what you have collected on the ATO’s behalf.
1B — GST on purchases
The GST inside your business purchases, again ÷ 11. Materials, fuel, tools, plant hire and subbie invoices, where a valid tax invoice exists.
Net GST is 1A minus 1B. If 1B is the larger — a quarter where you bought a lot of stock or a vehicle — you are in a refund position.
Where Hero365 fits
Every invoice and expense carries its GST as the job happens, so the quarter is already added up when the 28th comes round. Ask Hero AI to prepare your BAS and it assembles G1, 1A and 1B from the real figures and shows you where each number came from.
To be straight about lodgment: Hero365 does not lodge to the ATO. Lodging through SBR needs Digital Service Provider whitelisting we have not completed, so we prepare the numbers and you enter them in the ATO Business Portal, myGov, or hand them to your agent. GST on purchases is an estimate drawn from your receipts and flagged as one — never a fabricated claimable figure.
Common questions
What is a BAS statement?
A Business Activity Statement is the form you lodge with the ATO to report GST, and usually PAYG withholding and PAYG instalments alongside it. If you are registered for GST you have to lodge one for every period, even a quarter where you did no work — a nil BAS still has to go in.
When are BAS due dates?
For self-lodged quarterly BAS the standard dates are 28 October for July–September, 28 February for October–December, 28 April for January–March and 28 July for April–June. The December quarter gets the extra month because of the holidays. Monthly lodgers report by the 21st of the following month.
Do I have to register for GST?
Registration is compulsory once your GST turnover reaches $75,000 a year, or $150,000 for a not-for-profit, and it is compulsory from the first dollar if you drive taxi or rideshare. Below the threshold you can register voluntarily, which many trades do so they can claim the GST back on tools, materials and the ute.
How do I calculate the GST on my sales?
Divide by 11, do not take 10%. Australian prices are quoted GST inclusive, so an $11,000 job carries $1,000 of GST — taking 10% of the $11,000 would give $1,100 and overstate what you owe. The same divide-by-11 applies to your purchases when you work out what you can claim back.
What is Simpler BAS?
A reduced reporting version for businesses with a GST turnover under $10 million, which is nearly every trade business. You report just three GST labels — G1 total sales, 1A GST on sales and 1B GST on purchases — instead of the older, longer breakdown. You still have to keep the underlying records properly.
What can I claim GST back on?
Business purchases where GST was charged and you hold a valid tax invoice — materials, tools, fuel, plant hire, subcontractor invoices. You cannot claim on wages, on anything GST-free, or on the private-use share of something used for both. Get the split right at the time; reconstructing it at lodgment is where trades come unstuck.
What happens if I lodge my BAS late?
The ATO can apply a failure-to-lodge penalty that accrues per period, and interest runs on unpaid amounts. Lodging on time matters even when you cannot pay the whole balance — lodge, then arrange a payment plan, rather than not lodging at all.
Can I get more time by using an agent?
Usually yes. Lodging through a registered BAS or tax agent generally gives you a concessional due date later than the self-lodgment date, provided you are on their lodgment program. If you are consistently tight on the 28th, that alone is often worth the agent fee.
General guidance for Australian tradespeople, not tax advice, and current as at July 2026. Thresholds, due dates and concessions are the ATO's and do change — check current ATO guidance or ask a registered BAS or tax agent before acting on anything here.
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