How often
Monthly, quarterly or once a year
Registration comes first: the ATO says you must register for GST once your GST turnover reaches $75,000 or more ($150,000 for a non-profit), as at October 2026. After that, your turnover also decides how often you lodge.
| Cycle | Who it applies to | When it is due |
|---|---|---|
| Monthly | You must report monthly if your GST turnover is $20 million or more, or the ATO has directed you to. Below that, you can choose to. | The 21st of the following month: a July BAS is due on 21 August. |
| Quarterly | GST turnover under $20 million, unless the ATO has told you to report monthly. | Printed on your BAS. Lodging online may give an extra 2 weeks, except for the October to December quarter, whose due date already includes a one-month extension. |
| Annually | You are registered for GST voluntarily and your GST turnover is under $75,000 ($150,000 for a non-profit). | 31 October, or 28 February after the annual tax period if you don’t have to lodge a tax return then. |
The ATO prints the payment due date on each BAS, and when that date lands on a weekend or a public holiday, the deadline moves to the next business day. Using a registered tax or BAS agent may also bring different dates. The ATO’s due dates page lists the quarterly dates in full.
The labels
The few boxes a small business fills in
If your GST turnover is under $10 million (as at October 2026), you generally report GST using Simpler BAS, the ATO’s default method for small businesses. On it you report just three GST labels, and you don’t need the GST calculation worksheet. If you pay employees, the PAYG withholding labels join them.
| Label | ATO name | What goes there |
|---|---|---|
| G1 | Total sales | All your sales for the period: taxable, GST-free and input-taxed. Under the accounts method you choose whether your amounts include GST; enter 0 if you had no sales. |
| 1A | GST on sales | The total GST, including any adjustments, that you are liable to pay for the period. Enter 0 if there is none. |
| 1B | GST on purchases | The GST credits, including adjustments, you are eligible to claim. Enter 0 if there are none. |
| W1 | Total salary, wages and other payments | The gross payments you usually have to withhold from, such as employees’ salary, wages, allowances and leave loading. |
| W2 | Amounts withheld from the payments at W1 | The PAYG tax you withheld from those payments. |
Fill in only the labels that apply to you, in whole dollars with the cents left off, and with no negative figures or symbols such as $ or +. Other labels cover PAYG instalments, fringe benefits tax instalments, fuel tax credits and more; the ATO’s BAS section has a page for each.
An illustration, not your figures
GST is 10% on most goods and services. Picture a café that, in one quarter, makes taxable sales totalling $11,000 with GST included in the prices, and buys $3,300 of taxable supplies with tax invoices. With GST at 10%, one-eleventh of a GST-inclusive price is GST, so 1A would hold $1,000 and 1B would hold $300. Real figures rarely fall this neatly: GST-free items, private use, adjustments and your accounting basis all change them.
Timing
Which BAS a sale belongs to
That depends on the accounting basis you use for GST.
- Cash basis. A sale or purchase goes in the BAS for the period in which you received or made the payment, or part of it, which may not be the full price.
- Non-cash (accruals) basis. It goes in the earlier of the period in which any payment was made, or the period in which the invoice was issued.
The difference shows when a customer pays late. On an accruals basis, an invoice you issue belongs to that period’s BAS even if the customer hasn’t paid yet; on a cash basis it waits for the payment. Chasing the money itself is on board 3, being paid on time.
GST credits
Claiming credits: the paperwork comes first
- Only claim a GST credit on a purchase of $82.50 or more (including GST, as at October 2026) if you hold a tax invoice for it.
- Claim only the business share of something you use for business and private purposes.
- Leave out private expenses such as food or entertainment, and purchases with no GST in the price, such as bank fees and charges, stamp duty and GST-free items like basic foods.
- Claim within the 4-year time limit for GST credits.
- Keep your tax invoices and other GST records for 5 years.
The same rules run the other way when you sell. If a customer asks you for a tax invoice, you must provide one within 28 days, unless the sale was $82.50 or less including GST; for a sale under $1,000 it needs seven details, including that the document is intended to be a tax invoice, your identity and ABN, the date, what was sold, and the GST. The full list, with the ATO’s examples, is on its tax invoices page.
Quiet quarters and mistakes
A nil BAS, and fixing an error
A period with nothing to report still needs a BAS, lodged as nil by the due date. Online, choose Prepare, then Prepare as nil. The ATO also runs an automated phone service for nil BAS on 13 72 26, open at any hour, which takes up to 3 statements at a time; it can’t be used for an annual GST return, if you report GST by instalments, to vary a statement to nil, or when your statement has a pre-printed amount or rate above zero at labels F1, G21, T2, T7 or 7A.
Most GST mistakes can be corrected in your current BAS; if one can’t, you revise the original. A change after the sale, such as a price change or returned goods, is generally reported as an adjustment on your current BAS. The ATO’s page on fixing BAS mistakes sets out when each applies.
Paying it
Keeping the money ready, and when it isn’t
The ATO suggests setting aside the GST, PAYG withholding and super from your cash flow, so the money is there when each is due, and lodging all your BAS before your tax return to help reconcile the figures.
If you can’t lodge or pay in full and on time, the ATO asks you to contact it, or your registered tax professional, before the due date. A general interest charge applies to any amount not paid by the due date, and if you are in financial difficulty and owe $200,000 or less (as at October 2026), you may be able to set up a payment plan through ATO online services. Its page what if you can’t lodge and pay on time is the place to start.