By Joshua Occhino, Co-founder, Ezyiah
Short answer: For 2026–27, quarterly BAS is due on 28 October 2026 (Q1), 28 February 2027 (Q2, moving to Monday 1 March 2027 because the 28th is a Sunday), 28 April 2027 (Q3) and 28 July 2027 (Q4). If you lodge online yourself, the ATO gives an extra two weeks for Q1, Q3 and Q4. If a registered BAS or tax agent lodges electronically for you, the agent program usually allows about four extra weeks for those quarters. Monthly BAS is due on the 21st of the following month.
What are the 2026–27 quarterly BAS due dates?
| Quarter | Standard due date | Lodged online yourself (2-week concession) | BAS agent lodgement program |
|---|---|---|---|
| Q1: July–September 2026 | 28 October 2026 | 11 November 2026 | 25 November 2026 |
| Q2: October–December 2026 | 28 February 2027 (Sunday, so Monday 1 March 2027) | No concession | No concession |
| Q3: January–March 2027 | 28 April 2027 | 12 May 2027 | 26 May 2027 |
| Q4: April–June 2027 | 28 July 2027 | 11 August 2027 | 25 August 2027* |
*The Q4 agent date for 2026–27 falls in the 2027–28 agent lodgement program. Confirm it once the ATO publishes that program.
Sources: ATO due dates for lodging and paying your BAS, the two-week lodgment concession and the BAS agent lodgment program 2026–27.
If a due date falls on a weekend or public holiday, you can lodge and pay on the next business day.
Who gets the two-week online concession?
Businesses that receive and lodge their quarterly activity statements online can get an extra two weeks for Q1, Q3 and Q4. There's no extra time for Q2, because its 28 February due date already allows eight weeks. You don't apply: if you qualify, the due date shown online updates automatically. Some lodgers are excluded, including monthly GST reporters with quarterly instalments and large business clients. Check the terms and conditions.
How do BAS agent concession dates work?
Registered agents lodging electronically get the program dates in the table above for eligible clients. Two conditions catch firms out: the BAS must be lodged electronically, and the client's previous activity statement also needs to have been lodged electronically. Confirm eligibility per client rather than assuming the concession applies.
When is monthly BAS due?
Monthly BAS is due on the 21st of the month after the reporting month. For example, September 2026 is due 21 October 2026. December's monthly BAS is due 21 January, or 21 February for eligible agent-lodged clients under the agent program.
When is an annual GST return due?
Annual GST reporters lodge by 31 October after the end of the financial year. If you're not required to lodge an income tax return, the due date is 28 February.
How do you avoid the last-week rush?
The dates are predictable. The pressure isn't. When a batch of clients falls due on the same day, small problems such as a duplicate after a CSV import, a dropped bank feed or GST codes that have drifted turn into a bottleneck. Review reconciliation and GST coding during the quarter, not in the final week. See duplicate bank transactions after a CSV import and GST codes changing over time.
How Ezyiah helps
Ezyiah is an AI bookkeeper with its own ledger. It pulls live bank feeds daily, reconciles with AI and keeps the cash-basis BAS (and Extended BAS) building throughout the quarter, so the file is ready before the due date rather than started in the last week. Your accountant or BAS agent reviews and approves the BAS before lodgement. Ezyiah doesn't lodge with the ATO.
See how it works for business owners and accounting firms.
Frequently asked questions
When is the July–September 2026 BAS due?
28 October 2026 by default, 11 November 2026 if you lodge online under the two-week concession, or 25 November 2026 through a registered agent under the 2026–27 agent program.
Is there an extension for the October–December quarter?
No separate concession. The due date is 28 February 2027, which falls on a Sunday, so lodging and paying on Monday 1 March 2027 is on time.
What happens if I lodge late?
The ATO can apply a failure to lodge penalty and general interest charge on late payments. Contact the ATO or your agent early if you can't lodge on time. If there's nothing to report, you still need to lodge. See Nil BAS lodgement.
