If you are registered for GST, your BAS reporting cycle is generally monthly, quarterly or annual, with different lodgement and payment due dates. The Australian Taxation Office (ATO), checked on 1 October 2026, says monthly BAS is due on the 21st day of the following month, quarterly BAS is generally due on the 28th day shown in the quarterly schedule, and the annual GST return is due on 31 October.
After registering for an ABN and GST, the ATO will automatically send you a BAS when it is time to lodge. A registered business uses the BAS to report and pay GST, PAYG instalments, PAYG withholding and other taxes (ATO, checked on 1 October 2026).
Which BAS cycle applies?
Check the applicable cycle before preparing the BAS.
| BAS cycle | When it applies | Lodgement and payment due date |
|---|---|---|
| Monthly | GST turnover is $20 million or more, or the ATO has directed the business to report monthly | The 21st day of the month following the reporting period. For example, a July monthly BAS is due on 21 August. |
| Quarterly | GST turnover is below $20 million and the ATO has not directed the business to report monthly | Due dates depend on the quarter, as listed below. |
| Annual | The business voluntarily registered for GST and GST turnover is below $75,000, or $150,000 for a not-for-profit organisation | The annual GST return is due 31 October. If the business is not required to lodge a tax return, the due date is 28 February after the annual tax period. |
Source: Australian Taxation Office, Due dates for lodging and paying your BAS, checked on 1 October 2026.
These conditions explain why the first BAS after GST registration does not necessarily have a monthly cycle. Use the frequency stated by the ATO for the business rather than assuming it is the same as every other GST-registered business.
What are the quarterly BAS due dates?
The quarterly BAS is due on the 28th day of the month following the quarter.
| Reporting quarter | Due date |
|---|---|
| July, August and September | 28 October |
| October, November and December | 28 February |
| January, February and March | 28 April |
| April, May and June | 28 July |
Source: Australian Taxation Office, Due dates for lodging and paying your BAS, checked on 1 October 2026.
Mark the applicable reporting period and due date before beginning each BAS. The ATO also provides separate current deadlines for public holidays and other circumstances on its due-dates information; those additional dates are not stated on the official pages used for this article (checked on 1 October 2026).
How can a business lodge its BAS?
The ATO identifies these online options (checked on 1 October 2026):
- myGov online services for individuals and sole traders, where tax and superannuation can be managed together.
- Online services for business.
- SBR-enabled software, which can lodge information directly from financial, accounting or payroll software.
- Lodgement through a registered tax or BAS agent.
- Lodgement of a paper BAS by mail.
The appropriate channel depends on how the business manages its records and accounts. Record the lodgement as part of the business’s BAS compliance process and retain the supporting information needed to complete future BAS obligations.
Source: Australian Taxation Office, How to lodge your BAS, checked on 1 October 2026.
What if the business has nothing to report?
A business registered for GST must still lodge a nil BAS by the applicable due date, even when there is nothing to report for the period. The ATO says it can prepare and lodge this online by selecting Prepare, then Prepare as nil (checked on 1 October 2026).
A nil BAS can also be lodged by phone through the automated service on 13 72 26. The caller needs to have the relevant TFN or ABN and BAS document number available (ATO, checked on 1 October 2026).
Nil does not automatically mean the business is no longer registered for GST. Check the registration position separately if it is no longer conducting GST-covered activities.
Which records should be kept after lodging the BAS?
GST records must be kept for 5 years. They should show the income and expenses used to calculate and support the amounts reported and claimed as GST credits (ATO, checked on 1 October 2026).
The records include:
- all sales;
- tax invoices;
- other GST-related transactions;
- fees and expenses;
- wages; and
- other business costs.
Keep records that connect the BAS figures to the underlying transactions rather than retaining only the completed BAS. This makes the reporting period easier to review and supports the information needed for any later BAS, tax return or GST enquiry.
Source: Australian Taxation Office, GST records – business, checked on 1 October 2026.
When is a tax invoice important for GST?
For purchases, only claim a GST credit if the business holds a tax invoice for a purchase of $82.50 including GST or more. Sales invoices provided to customers must also show GST. Where a purchase is used for both business and personal purposes, the business can claim GST only on the business portion (ATO, checked on 1 October 2026).
These are separate checks to complete alongside the BAS:
- Confirm that supporting documents are held for the GST amount claimed.
- Check that customer sales invoices show GST as required.
- Separate the business and personal components of mixed-use purchases.
- Retain the records for 5 years.
Source: Australian Taxation Office, BAS and GST tips, checked on 1 October 2026.
Does a supplier not providing an ABN affect the BAS?
Yes, it can create an additional reporting item. If a supplier does not quote its ABN when providing goods or services, the buyer generally needs to withhold the top rate of tax from the payment and pay it to the ATO (ATO, checked on 1 October 2026).
The BAS may therefore need to reflect more than GST alone. It may include PAYG instalments, PAYG withholding and other taxes, depending on the business’s obligations.
Frequently asked questions
What is the usual due date for a monthly BAS?
A monthly BAS is due on the 21st day of the month following the reporting period. For example, a July monthly BAS is due on 21 August (ATO, checked on 1 October 2026).
Are quarterly BAS due dates all the same day of the month?
The quarterly due dates shown by the ATO are 28 October, 28 February, 28 April and 28 July for the July–September, October–December, January–March and April–June quarters respectively (ATO, checked on 1 October 2026).
Does a GST-registered business have to lodge a BAS if nothing was reported?
Yes. The business must lodge a nil BAS by the due date. It can prepare this online or use the ATO’s automated phone service on 13 72 26 (ATO, checked on 1 October 2026).
How long should GST records be retained?
GST records should be kept for 5 years. They should include sales, tax invoices, GST-related transactions, fees, expenses, wages and other business costs used to support the reported amounts and GST credit claims (ATO, checked on 1 October 2026).
Is a tax invoice required for every GST purchase?
For the ATO’s stated GST-credit rule, the business needs a tax invoice when the purchase totals $82.50 including GST or more. A mixed business-and-personal purchase supports a claim only for its business portion (ATO, checked on 1 October 2026).