BAS Due Dates 2026–27: Quarterly, Monthly and Agent Dates

The BAS due dates for 2026–27 are 28 October 2026, 2 March 2027, 28 April 2027 and 28 July 2027 for quarterly lodgers, and the 21st of the following month for monthly lodgers. Lodging online gives you two extra weeks on three of the four quarters, and a registered tax or BAS agent can give you more.

The one most sites get wrong this year is Q2. Its usual date, 28 February 2027, is a Sunday, and Monday 1 March is Labour Day in Western Australia. Because the ATO treats a public holiday in any whole state as a holiday for everyone, the ATO's own table puts the Q2 deadline at Tuesday 2 March 2027.

All dates on this page were checked against the ATO's published due dates, agent lodgment program and public holiday table on 9 October 2026. Your ATO online services account or agent shows the date that applies to you.

Quarterly BAS due dates 2026–27

The last quarter of the previous year, Q4 2025–26 (April to June 2026), was due 28 July 2026, or 11 August online and 25 August through an agent.

Q2 gets no online or agent concession because its 28 February due date already includes an extra month, giving you eight weeks after the quarter ends.

Monthly BAS due dates 2026–27

Monthly BAS is due on the 21st of the following month, moved to the next business day when that falls on a weekend:

The December extension is agent-only. The December monthly BAS moves from 21 January to 21 February (Monday 22 February 2027) only for businesses with turnover up to $10 million that report GST monthly and lodge electronically through a registered agent. If you lodge yourself, December is due 21 January like any other month. Several websites quote the February date without that condition.

There's no online-lodgment concession for monthly BAS.

Annual GST return due dates

If you're voluntarily registered for GST with turnover under $75,000 ($150,000 for not-for-profits), you can report GST once a year. The 2026–27 annual GST return is due 31 October 2027, which is a Sunday, so Monday 1 November 2027. If you don't have to lodge a tax return, it's due 28 February 2028. Agents may have different dates.

Why the dates move: weekends and public holidays

If a due date falls on a weekend or public holiday, you can lodge and pay on the next business day. The rule that catches people out is that the ATO counts a holiday that applies to the whole of any state or territory, not just your own. That's why WA's Labour Day on 1 March pushes the Q2 date to 2 March for businesses in every state, including those in Sydney or Melbourne.

The two-week online lodgment concession

If you receive and lodge your quarterly BAS online, through ATO online services or your accounting software, you automatically get two extra weeks to lodge and pay for Q1, Q3 and Q4. You don't need to apply. It doesn't cover:

• Q2 (October to December), which already has extra time;
• monthly BAS;
• quarterly PAYG instalment notices (forms R, S and T);
• monthly GST payers who pay PAYG instalments quarterly.

Tax and BAS agent dates

A registered agent can lodge later under the ATO's BAS agent lodgment program: about four weeks after the standard date for Q1, Q3 and Q4 (see the agent column above). These concession dates only apply when your previous statement was lodged electronically; a first BAS, or one after a paper lodgment, may be due earlier. If you use an agent, check your dates with them rather than relying on the general table.

Quarterly BAS: who lodges quarterly and what's on it

You lodge quarterly if your GST turnover is under $20 million, unless the ATO has told you to report monthly. Monthly reporting is compulsory at $20 million or more and optional below that. You can change cycle by phoning or writing to the ATO, but generally not if you've already changed in the last 12 months.

For most sole traders using Simpler BAS (the default for GST turnover under $10 million), the GST part of a quarterly BAS has just three figures:

• G1: total sales, including GST;
• 1A: GST on sales, which is 1/11 of your GST-inclusive taxable sales;
• 1B: GST on purchases, the GST credits you can claim.

If you pay PAYG instalments, they go on the same BAS at label 5A, due on the same quarterly dates. A sole trader generally starts paying instalments once the instalment income on their latest tax return is $4,000 or more.

What happens if you lodge or pay late

• Failure to lodge penalty: one penalty unit for every 28 days (or part of 28 days) your BAS is late, up to five units. The Commonwealth penalty unit rose to $364 on 1 July 2026, so a small business lodging a BAS that fell due after that date faces up to $1,820. Medium and large businesses pay multiples of that.
• General interest charge (GIC): charged daily on unpaid amounts. The rate for October to December 2026 is 11.51% a year. From 1 July 2025, GIC is no longer tax-deductible.
• The ATO usually warns you first, and generally doesn't apply the late-lodgment penalty to a BAS that results in a refund or nil amount. You can ask for penalties to be remitted.

If you can't pay, lodge on time anyway and set up a payment plan. Lodging late on top of paying late adds the penalty to the interest.

Make BAS time easier

Most BAS stress comes from working out the GST you collected over three months of invoices. Two habits fix that:

1. Set aside the GST as each invoice is paid. On a GST-inclusive invoice, 1/11 of the total is GST that belongs to the ATO; move it to a separate account when the money lands.
2. Keep your invoices in one system so you can pull the quarter's sales and GST in one go instead of searching emails.

InvoiceSonic adds 10% GST to your invoices, labels them as tax invoices when you're GST-registered, and exports a CSV with the GST split out for each quarter, ready for your BAS or your bookkeeper. Create a tax invoice with the invoice generator for Australia, or read do I charge GST under $75,000? if you're not sure you need to register.

Frequently asked questions

When is BAS due for each quarter in 2026–27?
Q1 (July to September) is due 28 October 2026, Q2 (October to December) 2 March 2027, Q3 (January to March) 28 April 2027, and Q4 (April to June) 28 July 2027. Lodging online gives two extra weeks for Q1, Q3 and Q4.

Why is the Q2 BAS due on 2 March 2027 and not 28 February?
28 February 2027 is a Sunday and Monday 1 March is Labour Day in Western Australia. The ATO moves due dates to the next business day after any whole-state public holiday, so Q2 is due Tuesday 2 March 2027 for everyone.

When is BAS due if I use a tax agent?
Agent lodgment program dates for 2026–27 are 25 November 2026 for Q1, 2 March 2027 for Q2 (no extension), 26 May 2027 for Q3 and 25 August 2027 for Q4. Your agent confirms the dates that apply to you.

Is BAS due on the 21st or the 28th?
Quarterly BAS is due on the 28th of the month after the quarter (28 February for Q2). Monthly BAS is due on the 21st of the following month.

What if the BAS due date falls on a weekend?
You can lodge and pay on the next business day. The same applies when the due date is a public holiday in any whole state or territory.

Do I need to lodge a BAS if I made no sales?
Yes. If you're registered for GST, you still lodge a BAS for each period, even if every amount is zero. The ATO generally doesn't apply a late-lodgment penalty to a nil BAS, but lodging on time keeps your record clean.

What is the penalty for lodging BAS late?
One penalty unit ($364 from 1 July 2026) for every 28 days late, up to five units, for a small business. Interest is also charged on any unpaid amount at the general interest charge rate, 11.51% a year for October to December 2026.

How do I change from quarterly to monthly BAS?
Contact the ATO by phone or in writing, or ask your agent. You generally can't change your reporting cycle again if you changed it in the last 12 months.