BAS and Tax Return Due Dates for 2026–27: The Right Order

Two deadlines run alongside each other for most Australian businesses: the regular activity statement cycle and the annual income tax return. They are not the same date, they are not worked out the same way, and they do not land at the same time of year. Mixing them up is one of the easiest ways to lodge something late for no good reason.

What follows is a plain-English walk through the 2026–27 dates, which cycle applies to you, and the order to tackle everything in. The dates come from ATO due date guidance and published 2026–27 BAS summaries. Your own activity statement always displays your due date, so treat that as the final word if anything here and the document disagree.

The two clocks: activity statements and income tax returns

A BAS, or business activity statement, is a reporting obligation tied to a set period. You report for that period, you lodge, and you pay. It repeats, either monthly or quarterly, depending on how you are set up.

The income tax return is an annual event. You report the full year, claim your deductions, and lodge once. For people lodging on their own, that date is 31 October.

Line those up and a sole trader on quarterly BAS has at least five lodgments in a year: four activity statements plus one tax return. Getting the order right starts with knowing which cycle you are actually on.

Quarterly BAS due dates for 2026–27

Quarterly lodgers work off fixed dates. The rule is the 28th day of the month following the end of the reporting period, which gives you almost a full month to finalise the figures before the statement is due.

Watch the December quarter. 28 February 2027 falls on a weekend, and published 2026–27 summaries list that date as either 28 February 2027 or Monday 1 March 2027. This is exactly the sort of detail worth checking against your own activity statement rather than relying on a remembered date.

Monthly BAS due dates for 2026–27

Monthly lodgers work off a rolling date rather than a fixed list. The due date is the 21st day of the month after the reporting period. July 2026 activity is due 21 August 2026. August activity is due 21 September 2026. The pattern carries through the financial year.

Once you are used to it, the rhythm is simple enough: the statement for last month is always due on the 21st of this month. The trap is the mental switch between the 21st and the 28th if your registration ever changes from monthly to quarterly, or the other way around.

The 31 October tax return deadline and where it fits

Unless you lodge through a registered tax agent, your income tax return is due by 31 October each year. Company returns are generally due by 28 February each year, which is a different track again.

During the 2026–27 financial year, the return most self-lodgers are dealing with covers the income year ended 30 June 2026, so the date is 31 October 2026. The return for the year ended 30 June 2027 follows the same rule and lands on 31 October 2027.

Where 31 October sits in the BAS calendar

Lay the dates side by side and the pinch points become obvious.

On quarterly BAS, the September quarter is due 28 October 2026 and the tax return is due 31 October 2026. That is three days apart, in the same week, at the end of October. Anyone who leaves both until late October is doing two jobs at once with the clock running.

On monthly BAS, the pressure is spread differently. September activity is due 21 October 2026 and October activity is due 21 November 2026, so the 31 October return deadline sits neatly in the gap between two statements. Tight, but workable if the records are already tidy.

Using a registered agent changes both dates

The 31 October date applies to people lodging on their own. Lodge through a registered tax agent and a different lodgment program applies, which is why 31 October is often described as the self-lodger deadline.

Agent programs also shift activity statement dates. Published summaries of the 2026–27 BAS agent arrangements list extensions including the September quarter moving to 25 November, the March quarter moving to 26 May, and the June quarter moving up to 25 August for electronic lodgers. Those dates sit well outside the standard 28th-of-the-month cycle and they apply to clients within an agent's program, not to everyone with an accountant on retainer.

The December quarter does not appear in that list of extensions, so confirm your own date with the person lodging for you. An extension is tied to the agent's lodgment program and to that agent lodging on your behalf, which means it is not something you can assume applies automatically.

Key 2026–27 dates at a glance

If you only keep one list, keep this one and then check it against your own activity statements.

Why the order matters more than the individual dates

An activity statement is a running record of your business for a set period. The annual return is built from the same underlying records. If a quarter is still unreconciled when you sit down to do the return, you end up guessing, and guessing almost always means missing a deduction you were entitled to claim.

Working in order, period by period and then annually, means the return is mostly assembled before you start it. You are checking figures rather than reconstructing a year from memory and a shoebox of receipts.

A simple order of operations for 2026–27

1. Confirm your cycle. Check whether your activity statements are monthly or quarterly, and note the due date printed on each one.
2. Put the dates in a calendar now. Quarterly lodgers: 28 October 2026, 28 February 2027 or 1 March 2027, 28 April 2027 and 28 July 2027. Monthly lodgers: the 21st of every month. Everyone: 31 October for the return.
3. Reconcile as you go. Match income and expenses to each reporting period instead of leaving twelve months of transactions for one long afternoon.
4. Lodge and pay the activity statement by its date. Lodging and paying are two separate actions with the same deadline attached.
5. Roll the year's figures into the return once the June quarter is behind you, or earlier if the records are already clean.
6. Lodge the return by 31 October, or by the date your registered agent gives you if you are in their program.

Record keeping is what makes both deadlines manageable

Most late lodgment stories come back to the same thing: records. Receipts in a drawer, a logbook nobody filled in, months of bank transactions nobody categorised.

Keeping records as you go turns the BAS period close into an afternoon and the annual return into a single session. It also means the figures on your activity statement and your return actually match, which saves awkward questions later. If you want a hand, Lodgya has a business and sole trader tracker built for GST and BAS reconciliation, a personal tracker for work-related deductions, and a rental property tracker for investment records. There is also a free 2026–27 ATO tax, BAS and super calendar if all you want is the dates in one place.

What to do when a due date shifts

When a due date lands on a weekend, the practical date moves, which is why the December quarter shows up as both 28 February 2027 and Monday 1 March 2027. Do not rely on memory for this one, and do not rely on a blog post either, including this one.

The date displayed on your activity statement is the date that applies to you. If you are ever unsure, check the ATO's own due date pages or ask your registered agent before the date passes rather than after.

Frequently Asked Questions

These are the questions that come up most often when people are lining up their activity statements and their annual return.

When is my BAS due if I lodge monthly?

Monthly BAS is due on the 21st day of the month following the reporting period. July activity is due 21 August, August activity is due 21 September, and the pattern continues through the financial year. Always check the due date shown on your own activity statement.

Is my tax return due on the same date as my BAS?

No. Activity statements run on their own monthly or quarterly cycle, while the income tax return is annual. If you lodge on your own, the return is due 31 October. Company returns are generally due 28 February. The two obligations draw on the same records, but they do not share a deadline.

Can a registered agent get me a later BAS due date?

Registered agents work under their own lodgment programs, and published 2026–27 summaries list later dates for some quarters, such as the September quarter moving to 25 November. Those arrangements apply to clients inside the agent's program. Confirm your date with your agent rather than assuming it.

Do I need to lodge both a BAS and a tax return?

They are separate obligations. If you report GST through activity statements, you lodge those for each reporting period and you also lodge an annual income tax return. Being on the monthly or quarterly cycle changes how often you report, not whether the annual return is required.

What happens if a due date falls on a weekend?

You will sometimes see the date written with an alternative weekday attached. The December quarter for 2026–27 is a good example, listed as 28 February 2027 or Monday 1 March 2027. Your activity statement displays the date that actually applies to you.