The Rosebery desk used to keep a paper calendar on the inside of a cupboard door. Four red rings a year for the quarterly activity statements, a smaller ring on the 21st if a client was monthly, and a pencil note for the agent’s extra week. Nobody needed software to know that 28 October was not the day you started the quarter.
Most files still treat the due date as the start of the work. That is how a café in Enmore spends the last Sunday of October reconstructing July. The calendar is not the hard part. The hard part is a monthly habit that makes the activity statement a reprint of a GST control account you already trust.
This essay is general information for Australian readers. It is not tax, legal or BAS advice. Due dates move when they fall on weekends and holidays, and the ATO lodgment program for agents is republished. Confirm the current dates on the ATO site and with your registered agent before you rely on a ring on a cupboard door.
The four quarterly dates most files actually use
If you report GST quarterly — the default for most small businesses under the monthly-turnover tests — the activity statement covers these tax periods:
- July to September — due 28 October
- October to December — due 28 February
- January to March — due 28 April
- April to June — due 28 July
February is short. The due date is still the 28th, not the end of the month plus a few days you invented. July is not “sometime before the tax return”. It is the 28th, in the middle of the year-end scramble.
Those dates are for self-lodgers. They are also the dates a lot of “we have an accountant” files still miss, because the owner assumed the agent’s concession applied automatically and the agent assumed the owner had sent the September bank rec.
Monthly BAS, and why you are on it
If the ATO has you on monthly GST — typically because GST turnover has gone over the published monthly threshold, or because you chose monthly — the activity statement is due on the 21st of the following month. January GST is due 21 February. June GST is due 21 July.
Monthly is not a moral failing. It is a cash-flow and compliance rhythm. A media production company in Alexandria that crossed the line and stayed on quarterly “because we always have” is not being efficient. It is lodging on the wrong cycle. Check your latest activity statement header. The tax period is printed on it. If you think you are quarterly and the form says 1 to 31 March, you are monthly.
Monthly files need a closer that finishes in ten days, not a quarterly archaeology. The month-end close is written for that file.
Next business day, not next convenient day
If 28 October is a Saturday, or 21 April is Easter Monday, you may lodge and pay on the next business day. That is an ATO rule, not a mood. It does not extend to the following Friday because you are on a job in Wollongong.
Public holidays are state-specific. A due date that is a public holiday in New South Wales but not in Western Australia is still a public holiday for a Sydney lodger. The Perth desk used to write the local holiday on the same cupboard calendar. If you lodge from two states, use the next day that is a business day where the entity operates, and do not cut it fine.
Do not rely on a software reminder that was set in 2023. Recheck the year when you plan the close.
The tax-agent concession is real, and it is not yours by osmosis
Registered tax agents and BAS agents work to an ATO lodgment program. For most quarterly activity statements that program gives extra time — often several weeks — provided the statement is lodged through the agent and the agent is meeting the program’s conditions.
It is not a blanket extra month on every form. Some periods have little or no extra time. Some clients lose the concession if the agent’s program is withdrawn or if prior statements are outstanding. Some owners think they have an agent when they have a bookkeeper who is not registered, or a registered agent who has not listed them on the program.
If you want the concession:
- Confirm, in writing, that a registered tax agent or BAS agent is lodging the activity statement.
- Ask for the due date they are working to this year, for each quarter.
- Give them a closed file at least ten days before that date, not the afternoon of it.
The concession is extra time to lodge a finished statement. It is not extra time to find the September fuel dockets. Source documents still have to exist in September.
What else rides on the same form
The activity statement is often more than GST. Depending on the entity it can carry:
- GST on sales and purchases (or the Simpler BAS trio)
- PAYG withholding you deducted from wages and some payments
- PAYG instalments toward the year’s income tax
- Fuel tax credits on label 7D, if you claim them
- other labels if wine equalisation or luxury car tax applies to you
PAYG withholding is not optional timing. Single Touch Payroll has already reported the pay. The BAS is where many entities still remit the withheld amount. If the withholding on the statement does not match the STP year-to-date for the same period, stop. Do not “plug” 4 to make the form submit.
PAYG instalments are a different number: a prepayment of income tax, often calculated by the ATO. A base-rate company pays company tax at 25 per cent; other companies pay 30 per cent. The instalment is not that rate applied to this quarter’s cash. Changing or varying an instalment is a tax-agent decision with a reason code. Do not vary it because the quarter felt tight.
Super Guarantee at 12 per cent from 1 July 2025, and Payday Super from 1 July 2026, do not live on the BAS the way they used to in older minds. Super leaves with the pay. The activity statement is not your super safety net.
Lodge is a reprint
The original firm talked about validated numbers for a BAS return. The mechanism was boring:
- Every bank, card and loan reconciled to a statement for each month in the tax period.
- GST control account equal to the draft 1A and 1B (and G1, if you still look at it).
- A tax-rate report showing no private spend coded as creditable, no capital coded as a coffee, no GST-free clinic fees coded as taxable.
- PAYG withholding tied to the STP summary.
- Fuel tax credits, if any, tied to litres and the current ATO rate table — not to a guess. See fuel tax credits and the work vehicle.
- A one-page working paper that a stranger could reprint from.
If step 2 fails, the statement is not ready. Software will still let you lodge. That is not a blessing.
A café that runs this pack in the first ten days of each month spends an hour in October. A café that starts in the last week of October spends a weekend, and still lodges a number it cannot explain in April.
A working-paper page that earns its keep
Print or PDF, each quarter, and keep it with the year:
- tax period and due date (self-lodger and agent, if different)
- GST method (cash or accrual — see cash versus accrual)
- G1 / 1A / 1B (and the extra labels if you are on full reporting)
- withholding and instalments
- fuel tax credit litres and the rate table you used
- a sentence on anything odd: a $40,000 oven, an insurance recovery, a grant, a cancelled invoice
- who lodged, and the receipt number
That page is what you send the tax agent in July. It is what you open if the ATO writes. It is what stops the next bookkeeper from relodging September because they could not see how 1A was built.
Books a tax agent can use is the longer version of this test. The calendar is the shorter version: the working paper exists before the due date, or the due date is theatre.
Payment, plans and the thing people mix up
Lodgement and payment are different buttons. Lodge on time even if the bank cannot clear the payment that day. An overdue lodgement is a compliance failure with its own shape. An overdue payment is a debt. The ATO will usually talk about a payment plan for a debt. It is less fond of a statement you never lodged.
If you know a quarter will be large — a clinic that bought an imaging machine, a tradie who was paid three retentions at once on accrual GST — say so in the month it happens, not on the 27th. GST of 10 per cent on a $55,000 invoice is $5,000 that should have been sitting in a clearing account. If it was spent on wages, the calendar cannot help you. A thirteen-week cash view can.
How a boutique calendar actually ran
The Gardeners Road cupboard had more than due dates. It had the week the close started (the 4th), the week the owner answered queries (the 8th), and the week the agent was sent the pack (the 12th). Monthly clients had a thinner version of the same three beats.
You can run that without a firm. Put the four quarterly due dates in a shared calendar. Put a close on the 4th of each month. Put a “questions for the owner” list next to it. Refuse to start coding on the 27th.
If you are choosing whether to stay quarterly or whether Simpler BAS still serves you, those are content questions — see the BAS and GST hub. The calendar is the promise that whatever you chose, you will lodge it on a number you already had. The original copy said the team would free your time. This is the unfashionable way that happens: dates on a door, a reprint, and no Sunday panic.
