A BAS (business activity statement) is the ATO form you lodge once you're registered for GST, usually every quarter. It reports the GST you collected on sales, the GST you paid on business purchases, and nets the two off: collect more than you paid and you pay the ATO the difference; pay more than you collected and you get a refund. If you withhold tax from wages, that rides on the same form.
Register for GST →5-minute form · usually done in 4 business hours
What's actually on the form.
A standard GST-only BAS comes down to three numbers:
- G1, total sales. Everything you billed for the period, including GST-free sales.
- 1A, GST on sales. The GST you collected: one-eleventh of your taxable sales (the ÷11 rule).
- 1B, GST on purchases. The credits you're claiming back on business costs, supported by tax invoices for anything over $82.50.
1A minus 1B is the result. Positive, you pay; negative, the ATO refunds you. If you're registered for PAYG withholding (you employ people), labels W1 and W2 add the wages you paid and the tax you withheld. The same figures your payroll software already reports each pay day under Single Touch Payroll, wrapped up with an STP finalisation by 14 July each year. Some businesses also see a PAYG instalment label, a prepayment of their own income tax the ATO adds automatically. If the numbers do not look right, talk to one of our agents before you lodge rather than after. Rideshare drivers fill this in differently, which the rideshare BAS guide walks through.
When it's due.
Your reporting cycle is set at registration: quarterly is the default and by far the most common, monthly suits businesses that want faster refunds, and annual is only available under the $75,000 threshold. Each cycle has fixed due dates: quarterly BAS is due the 28th of the month after the quarter ends.
A nil BAS still has to be lodged.
No sales this quarter? You still lodge, a "nil BAS" takes two minutes, and skipping it is what triggers penalties, not the zero. The ATO charges failure-to-lodge penalties on late forms and interest on late payments; the two are separate, so lodge on time even when you can't pay on time and sort a payment plan for the balance.
Keeping it a 20-minute job.
- Pick the right accounting method at registration: cash vs accrual decides when sales hit your BAS, and cash is kinder to small-business cash flow.
- Keep tax invoices as you go, anything over $82.50 needs one to claim the credit (what a valid one looks like).
- Use software or a bookkeeper: if sales and purchases are categorised through the quarter, the BAS is a read-out, not a project.
Quick answers.
Do I have to lodge a BAS if I made no sales?
Yes. A nil BAS is still a BAS. Lodging it takes minutes; not lodging it is what attracts failure-to-lodge penalties, even when nothing was owed.
What happens if I lodge my BAS late?
The ATO can charge a failure-to-lodge penalty that grows the longer it's outstanding, and general interest accrues on any unpaid GST. Lodgement and payment are penalised separately: so always lodge on time, even if you need a payment plan for the money.
Can I do my own BAS?
Yes, through ATO online services. Many businesses hand it to a BAS or tax agent instead, which also usually buys extra lodgement time under the agent lodgement program.
Is a BAS the same as a tax return?
No. The BAS reports GST (and PAYG) during the year, usually quarterly. Your tax return reports income annually. A GST-registered business lodges both.
Related guides: BAS calculator · BAS due dates · Fixing BAS mistakes · Cash vs accrual GST · How GST credits work
Not registered for GST yet? That's step one.
Lodged by Registered BAS Agent 25972850 · tax deductible · free help on 1800 546 526.