BAS Due Dates 2026-27: Quarterly Dates and Common Mistakes
Last updated: 25 October 2026.
Late or incorrect BAS lodgments are one of the most common compliance headaches for small businesses in Sydney. Most problems come down to knowing your dates and keeping tidy records through the quarter. In this guide we set out the 2026-27 BAS due dates, including the extra time that can apply when a registered BAS agent lodges for you, and the mistakes we see most often.
The short version: the July to September 2026 quarter is due on Wednesday 28 October 2026. The next quarterly date, for October to December, is 28 February 2027. That is a Sunday, so the effective due date is Monday 1 March 2027.
How BAS due dates work
A business activity statement (BAS) is how you report and pay GST, PAYG withholding, PAYG instalments and some other amounts to the ATO. How often you lodge depends on your GST turnover and your registration. The due date for lodging and paying is shown on your BAS, so always treat that as the final word for your business.
According to the ATO’s due dates page (last updated 17 September 2026):
- Monthly reporting: required if your GST turnover is $20 million or more, or if the ATO has directed you to report monthly. The lodgment and payment date is the 21st day of the month after the reporting period. A July monthly BAS, for example, is due on 21 August. Smaller businesses can choose monthly reporting too, which some do for cash flow reasons.
- Quarterly reporting: required if your GST turnover is under $20 million and you haven’t been told to report monthly.
- Annual reporting: for businesses that are voluntarily registered for GST with GST turnover under $75,000 (or $150,000 for not-for-profit organisations). The due date is generally 31 October, although the ATO sets a different date in some circumstances, so check its page.
Quarterly BAS due dates for 2026-27
| Quarter | Period | Standard due date |
|---|---|---|
| 1 | July, August, September 2026 | Wednesday 28 October 2026 |
| 2 | October, November, December 2026 | 28 February 2027 (a Sunday, so Monday 1 March 2027) |
| 3 | January, February, March 2027 | Wednesday 28 April 2027 |
| 4 | April, May, June 2027 | Wednesday 28 July 2027 |
The ATO says that if a due date falls on a weekend or public holiday, you have until the next business day to lodge and pay. That is why the 28 February 2027 date moves to Monday 1 March 2027. Your own due date is printed on your BAS, so check it before you rely on any date in this article.
Extra time when a BAS agent lodges
The ATO says that if you lodge online you may be eligible for an extra two weeks to lodge and pay your quarterly BAS, and that you may also get extra time if you lodge through a registered BAS agent. For BAS agents lodging electronically, the ATO’s 2026-27 lodgment program sets these dates for eligible quarterly BAS:
| Quarter | Standard due date | BAS agent lodgment program date |
|---|---|---|
| 1, 2026-27 | 28 October 2026 | 25 November 2026 |
| 2, 2026-27 | 28 February 2027 | No extra time |
| 3, 2026-27 | 28 April 2027 | 26 May 2027 |
| 4, 2026-27 | 28 July 2027 | 25 August 2027 (the ATO lists this as to be confirmed when the 2027-28 program is developed) |
A few points to keep in mind:
- No extra time for the December quarter. The ATO says a later due date does not apply to quarter 2, because its due date already includes a one-month extension.
- Eligibility matters. The agent dates apply to eligible BAS that are lodged electronically, and they depend on the previous BAS also having been lodged electronically. If it is a client’s first BAS, or the previous one was lodged on paper, an earlier due date may apply. Some BAS are not eligible at all, for example where GST is reported monthly.
- Your agent confirms the date. The dates your BAS agent sees for your business are what count, so ask which date applies to you.
Common BAS mistakes we see
1. Mixing business and personal spending
When personal purchases land in the business account, GST claims and expense totals go wrong quickly. A separate business bank account and card make every later step easier.
2. Claiming GST without a valid tax invoice
Generally you need the right documentation to claim a GST credit. If receipts sit in a glovebox or an inbox until the day before lodgment, claims get missed or made without support.
3. Leaving bank reconciliation until the last minute
Unreconciled transactions hide duplicates, missing sales and wrong GST codes. Reconciling monthly, or even weekly, turns the BAS into a quick review instead of a rebuild.
4. Using the wrong GST code
Some sales and purchases are GST-free or input-taxed, and others include GST. Wrong codes in your software lead to wrong figures at labels such as G1 or 1A. Review codes on unusual items rather than accepting software defaults blindly.
5. Forgetting PAYG withholding and instalments
If you have employees, your BAS also reports PAYG withholding. Payroll that is not reconciled to the BAS is a frequent source of errors. Super is now a separate, more frequent deadline: for pay from 1 July 2026, the ATO’s Payday Super rules require super to reach the fund within 7 business days of payday. See our Payday Super guide.
6. Paying late because cash was already spent
GST collected from customers is not your money. Setting aside an amount each time you get paid avoids a nasty surprise. If you can’t pay on time, the ATO says to contact it or your registered tax professional before the due date to discuss support options, rather than waiting.
7. Not fixing errors once you find them
If you discover a mistake in a lodged BAS, the ATO has guidance on fixing BAS mistakes or making adjustments. Finding a problem early is much better than leaving it.
A simple routine that keeps you on time
- Put your lodgment dates in the calendar, with a reminder two weeks ahead.
- Reconcile bank feeds at least monthly.
- Store receipts and invoices digitally as you go.
- Review the GST and payroll reports before the BAS is prepared.
- Set aside GST and PAYG amounts in a separate account.
How we help
We prepare and lodge BAS for Sydney businesses and check the figures against the books before anything goes to the ATO. If you would like to see what that looks like, read about our BAS agent service in Sydney, or see how our bookkeeping keeps your records ready for each lodgment. Not sure who should be lodging? Our guide on what a BAS agent is explains the difference. When you are ready to talk, get in touch with us.
Frequently asked questions
When is the next quarterly BAS due?
For the July to September 2026 quarter the standard ATO due date is Wednesday 28 October 2026. The October to December quarter is due 28 February 2027, which is a Sunday, so the effective date is Monday 1 March 2027. Your own due date is shown on your BAS, so confirm it there.
Can I get extra time to lodge my BAS?
The ATO says you may be eligible for an extra two weeks if you lodge online, and you may get extra time through a registered BAS agent. For eligible BAS lodged electronically by an agent, the 2026-27 ATO program dates are 25 November 2026 for quarter 1 and 26 May 2027 for quarter 3. There is no extra time for the December quarter. Check your situation with the ATO or your BAS agent.
Why is the December quarter BAS not extended?
The ATO says a later lodgment and payment due date does not apply to quarter 2 because its due date, 28 February, already includes a one-month extension.
What happens if I cannot pay my BAS on time?
The ATO recommends contacting it or your registered tax professional before the due date to discuss support options such as a payment plan. Interest and further action can apply if you leave it.
How often should my books be reconciled?
At least monthly. More frequent reconciliation makes the BAS faster and errors easier to spot.
Sources and further reading
- ATO: Due dates for lodging and paying your BAS (last updated 17 September 2026)
- ATO: BAS agent lodgment program 2026-27 (last updated 1 July 2026)
- ATO: Business activity statements (BAS)
- ATO: Payment deadlines for Payday Super (last updated 29 September 2026)
This article is general information, not personal advice. Rules and dates can change, so check ato.gov.au or acnc.gov.au for the latest, or speak to us about your situation.