If your GST turnover is under $10 million, your first BAS asks for three GST figures: G1 (your total sales), 1A (the GST you collected on sales) and 1B (the GST you paid on business purchases). You subtract 1B from 1A and pay the difference, or get a refund if 1B is bigger.
This is general information. A registered tax or BAS agent can say how it applies to you.
This is the ATO’s Simpler BAS method, and it is the default for small businesses. The details below are as at October 2026, from the ATO’s own pages (linked at the end).
Who uses Simpler BAS
The ATO says that if your GST turnover is less than $10 million you use the Simpler BAS reporting method, unless you pay GST by instalments. At $10 million or more you use the full reporting method, which adds G2 (export sales), G3 (other GST-free sales), G10 (capital purchases) and G11 (non-capital purchases). Your BAS might also show other labels, such as fuel tax credits, if they apply to you.
The ATO works from the GST turnover in its records (the figure you gave it when you registered, or since), and rolls your reporting method over each financial year. If your turnover changes enough to move you across $10 million, you contact the ATO.
A BAS is for businesses registered for GST. You must register once your GST turnover reaches $75,000 ($150,000 for a non-profit organisation), and the ATO says to do it within 21 days of reaching the threshold. Some businesses must register whatever their turnover, such as taxi and ride-sourcing drivers. Your BAS may also include PAYG instalments, PAYG withholding and other amounts, depending on what you’re registered for.
The three labels
| Label | What goes in it | Where the number comes from |
|---|---|---|
| G1 Total sales | All your sales for the period: taxable, GST-free and input-taxed. You choose whether to report it with GST included or excluded, and you must indicate which | Your sales records for the period |
| 1A GST on sales | The GST in your taxable sales | One eleventh of your GST-inclusive taxable sales |
| 1B GST on purchases | The GST included in the price of your business purchases (your GST credits) | One eleventh of the GST-inclusive price of business purchases with GST in the price, with a tax invoice for any over $82.50 |
Three points trip up first-timers.
G1 is all sales, not only taxable ones. GST-free sales (for example exports of services to a customer outside Australia) and input-taxed sales (such as residential rent) go in G1 as well. Only taxable sales go in 1A.
1B is the GST, not the purchase total. The ATO says you do not report your total purchases on a Simpler BAS. You report only the GST included in them. Purchases with no GST in the price, such as ones from a supplier who isn’t registered for GST, don’t go in 1B.
1B needs a tax invoice for purchases over $82.50. For a purchase costing $82.50 or less (GST included), the ATO says you should have a tax invoice, cash register docket, receipt or invoice. Above $82.50 you need a tax invoice before you can claim the credit. If a supplier hasn’t given you one, you can ask for it, and wait to claim until it arrives.
Cash or accrual: which quarter does a sale or purchase belong to
You pick one of two GST accounting methods. Businesses with an aggregated turnover under $10 million can choose either.
On the cash basis, you count a sale in the period you’re paid, and a purchase in the period you pay for it. On the non-cash (accrual) basis, you count a sale in the period you issue the tax invoice or are paid, whichever comes first, and a purchase when you receive the supplier’s invoice or pay, whichever comes first. Cash lines your GST up with the money moving through your bank; non-cash tracks what’s owed and owing. A change from cash to non-cash takes effect from the first day of a tax period.
Whichever you use, you can claim GST credits for up to 4 years, so a purchase you missed this quarter isn’t lost.
An example quarter
Sam is a freelance designer, a sole trader registered for GST, using the cash basis. Here is the July to September quarter.
Sales received
- Client invoices paid with GST: $38,500 including GST. The GST in that is $38,500 / 11 = $3,500.
- One overseas client, paid $2,000 for design work. Services provided to a customer outside Australia are generally GST-free exports (specific rules apply), and this one qualifies, so there is no GST on it.
Purchases paid, with tax invoices
| Purchase | Price incl. GST | GST in it |
|---|---|---|
| Co-working desk | $1,100 | $100 |
| Phone and internet | $165 | $15 |
| Software subscriptions | $330 | $30 |
| Accountant | $660 | $60 |
| Total | $2,255 | $205 |
Three other items stay off the BAS this quarter. A $220 monitor was bought with only a card receipt, so Sam asks the supplier for a tax invoice and waits to claim its $20 GST. A $44 market-stall purchase had no GST in the price. A $550 freelancer’s invoice has been received but not paid by 30 September, and on the cash basis it belongs to the quarter in which Sam pays it.
The BAS
| Label | Amount | How |
|---|---|---|
| G1 Total sales (GST included) | $40,500 | $38,500 taxable + $2,000 GST-free |
| 1A GST on sales | $3,500 | $38,500 / 11 |
| 1B GST on purchases | $205 | $100 + $15 + $30 + $60 |
Sam owes 1A minus 1B: $3,500 - $205 = $3,295, due by the date on the BAS. Sam would also tick that G1 was reported with GST included.
Getting it lodged
The ATO issues your BAS about 2 weeks before the end of your reporting period, with the due date on it. You can lodge online (through Online services for individuals and sole traders in myGov, Online services for business, or compatible software), through a registered tax or BAS agent, or by mail. Lodging online can give you extra time, and an agent may too. Check the date on your BAS.
Questions
Does everyone have to lodge a BAS?
Businesses registered for GST do. If you aren’t registered, you don’t lodge a BAS for GST, but you do need to register once your GST turnover reaches $75,000 (or straight away for some businesses, such as taxi and ride-sourcing drivers).
Can I report G1 without GST?
Yes. The ATO lets you report G1 either GST-inclusive or GST-exclusive, as long as you indicate your choice.
What if I get a number wrong?
What to do depends on the mistake and on whether you’ve already lodged. A registered tax or BAS agent, or the ATO, can tell you how to correct it.
Do I need an agent for my first BAS?
No. Plenty of small businesses lodge their own BAS online. An agent can prepare and lodge it for you, and may get you extra time to lodge.
Where Beans fits
For a first BAS, the hard part is usually having the books ready, not the three labels. Beans keeps the books as you go: bank lines and receipts are recorded in the right entity’s books as they arrive, receipts can be emailed in, and it flags a purchase that’s still missing a tax invoice, so you can chase the supplier before the BAS. It works up the BAS from books that are already done, and the BAS waits for your yes. Beans doesn’t hold the credit back: when the BAS is ready, it lists the bills still missing a tax invoice, and you choose whether to keep claiming or not.
Sources (all ato.gov.au, checked 15 October 2026): GST reporting methods, Quarterly GST reporting, Simpler BAS GST bookkeeping guide, Choosing an accounting method for GST, When you can claim a GST credit, Registering for GST, How to lodge your BAS, When and how to report and pay GST.
General information, not tax advice.