Businesses registered for GST (Goods and Services Tax) must lodge and pay a Business Activity Statement (BAS) regularly. If you’re on a quarterly BAS cycle, keeping track of the Quarterly BAS Due Dates is critical to avoid penalties and interest. (Most GST-registered businesses with turnover under $20 million report quarterly by default, whereas larger businesses may have monthly BAS.) Missing a BAS deadline can result in failure to lodge penalties and can hurt your cash flow through General Interest Charge (GIC) interest on late payments. This article outlines the quarterly BAS lodgement deadlines and tips to ensure you meet them.

Quarterly BAS Due Dates: Key Lodgement Deadlines

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Standard Quarterly BAS Deadlines

For small and medium businesses in Australia, BAS is lodged quarterly. Each quarter has a standard due date set by the Australian Taxation Office (ATO). As of current ATO guidelines, the due dates are as follows:

  • Q1 (July–September): Due 28 October
  • Q2 (October–December): Due 28 February (extended due to holidays)
  • Q3 (January–March): Due 28 April
  • Q4 (April–June): Due 28 July

These deadlines apply if you lodge the BAS yourself (for example, through the ATO Business Portal or myGov). The ATO confirms that quarterly BAS deadlines fall on the 28th of the month following each quarter’s end (ATO, 2025). (Note: Businesses that report monthly have different due dates – generally the 21st of the next month – but this article focuses on the quarterly cycle used by most SMEs.)

Agent and Online Lodgement Extensions

You may get extra time to lodge if you lodge electronically or use a registered tax/BAS agent. The ATO grants a two-week extension for quarterly BAS when lodged online or via an agent, except for the December quarter. In practice, this means:

  • Q1 deadline extended to roughly 25 November (when lodging through an agent)
  • Q3 deadline extended to roughly 26 May
  • Q4 deadline extended to roughly 25 August
Agent and Online Lodgement Extensions - Quarterly BAS Due Dates

Quarter 2 (the Dec quarter) already has a built-in extra month (due 28 Feb), so no further extension applies for that period. Always check the exact extended dates each year with your agent – they can vary slightly depending on calendar shifts and ATO updates. Lodging via an agent not only gives you more time but also ensures your BAS is prepared accurately. For more information on these agent extensions, you can read our BAS due dates extension guide.

Tips to Meet BAS Due Dates

Staying on top of BAS obligations requires good organisation. Some tips to help include:

  • Mark your calendar: Note the standard due dates (28 Oct, 28 Feb, 28 Apr, 28 Jul) at the start of the financial year. Set reminders a week or two in advance of each deadline.
  • Use ATO reminders: The ATO app and online services let you set up due date alerts. These can prompt you as a deadline approaches.
  • Prepare in advance: Don’t leave BAS preparation to the last minute. Reconcile your accounts and gather GST data (sales, expenses, invoices) regularly, ideally monthly. That way, quarter-end BAS preparation is faster and less prone to error.
  • Consider an agent: A registered BAS agent or tax accountant can take care of lodgement for you. Agents have later lodgement dates under the ATO’s program, as noted above. If BAS time is stressful or confusing, professional help can ensure it’s done correctly and on time.
  • Communicate with the ATO: If you cannot lodge or pay on time due to unforeseen circumstances (illness, natural disaster, etc.), contact the ATO before the due date. They may grant a lodgement deferral or a payment plan in special cases.

Consequences of Missing a BAS Deadline

Failing to lodge and pay your BAS by the due date can lead to a Failure to Lodge (FTL) penalty. For a small entity, this penalty accrues at one penalty unit (around $313) for each 28-day period the BAS remains overdue, up to a maximum of five penalty units. For example, if your BAS was due on 28 July but you lodged it on 20 August (23 days late), the ATO could impose one penalty unit for that period of lateness. In addition, the ATO will charge GIC interest on any overdue BAS amount from the day after the due date until payment is made.

Consequences of Missing a BAS Deadline - Quarterly BAS Due Dates

Even if your BAS results in a refund or no tax payable, late lodgement can still attract penalties. The ATO generally won’t penalise a one-off slight delay if you fix it quickly, but repeated late BAS lodgements will draw stronger action. In serious cases of non-compliance, the ATO can cancel your extended lodgement privileges or even issue a default assessment of your liabilities. The safest approach is to treat the quarterly BAS due dates as firm deadlines. By planning ahead and leveraging reminders or professional support, you can ensure your business meets BAS obligations without last-minute scrambles.

Don’t risk penalties—TTS & Associates can help you stay compliant. Contact us today.