A BAS quarter is one of four quarterly periods used by the Australian Taxation Office for Business Activity Statement reporting under the Australian financial year. Most GST-registered Australian businesses lodge quarterly BAS returns covering GST, PAYG withholding, and PAYG instalments.
The four quarters
BAS quarters align to the Australian financial year:
- Q1 — 1 July to 30 September
- Q2 — 1 October to 31 December
- Q3 — 1 January to 31 March
- Q4 — 1 April to 30 June
The quarter number resets with the financial year on 1 July, not with the calendar year on 1 January.
Lodgement and payment due dates
The standard ATO due date is 28 days after the quarter ends, with one exception:
- Q1 — 28 October
- Q2 — 28 February (extended from 28 January to accommodate the holiday period)
- Q3 — 28 April
- Q4 — 28 July
Businesses lodging through a registered tax or BAS agent typically receive a further extension. Full rules are published on the ATO BAS due dates page.
Monthly and annual alternatives
Quarterly is the default. Businesses with annual GST turnover of 20 million dollars or more must lodge monthly. Businesses voluntarily registered for GST with turnover below 75,000 dollars may lodge annually.