BAS Due Dates 2026-27: Every Deadline, Plus What If You've Missed One

What are the BAS due dates for 2026-27?

Quarterly BAS due dates for 2026-27 fall on the 28th of the month after each quarter ends, with one exception in the December quarter which gets extra time over the holidays. The table below shows both the standard due date and the later date you usually get if a registered tax or BAS agent lodges on your behalf.

It's worth writing these four dates straight into your diary or phone calendar now, rather than waiting for a reminder. Most missed BAS happen simply because the date crept up, not because anyone was trying to avoid it.

What are the monthly BAS due dates?

Monthly BAS are due on the 21st of the following month, with no extra agent concession like the quarterly dates get. So a July BAS is due 21 August, an August BAS is due 21 September, and so on for every month of the year. Businesses on monthly reporting are usually those with GST turnover above the threshold that requires it, or that have chosen monthly reporting voluntarily for better cash flow visibility.

What happens if the due date falls on a weekend or public holiday?

The due date simply moves to the next business day. If 28 October falls on a Saturday, for example, the effective deadline shifts to the following Monday. This applies to both quarterly and monthly BAS, and to public holidays in the same way. It's a small buffer, but it's not something to plan around deliberately, since state-based public holidays can vary and it's easy to miscalculate.

What happens if your BAS is overdue?

An overdue BAS attracts a failure to lodge (FTL) penalty, calculated in penalty units for every 28 days (or part of) the lodgement is late, up to a cap. Each overdue BAS is treated as its own document, so if you're behind on several quarters the penalties can add up quickly across each one. See our failure to lodge penalty guide for exactly how the amounts are calculated and how remission requests work.

Beyond the penalty, an overdue BAS can also delay GST refunds you're owed, and repeated non-lodgement tends to draw closer ATO attention over time. None of this is a reason to panic - it's simply a reason to get the outstanding BAS lodged as soon as practical.

Several BAS behind? How does catch-up work?

You lodge the outstanding BAS periods in order, usually oldest first, so the GST position for each quarter is accurate before moving to the next. If your bookkeeping has gaps, a tax agent can often reconstruct sales and purchase figures from bank statements, invoicing software or supplier records rather than relying on receipts you may have lost - our guide on doing a tax return without receipts covers the same reconstruction approach used for BAS.

If you've also fallen behind on income tax returns at the same time, which is common for sole traders juggling both obligations, it's usually most efficient to sort both in the one engagement. Our overdue BAS and GST service is built specifically for multi-quarter catch-ups like this, working alongside our broader guide to overdue tax returns.

Can you get more time to lodge a BAS?

Yes, in some cases. Being registered with a tax or BAS agent under the agent lodgement program is the main way most people get extra time automatically, as shown in the table above. Beyond that, the ATO can sometimes grant a further deferral if you contact them (or have an agent contact them) with a genuine reason before the due date passes. Deferrals are considered case by case and aren't guaranteed, so it's best to ask early rather than after the date has already gone.

BAS due dates checked 30 July 2026 for the 2026-27 financial year.

General information only - not personal tax, financial or legal advice. Consider your own circumstances or speak to a registered tax agent. Remission of penalties or interest and payment plans are decisions of the ATO and outcomes can't be guaranteed.