Quick answer
Good BAS planning starts with treating the GST you collect and the PAYG you withhold as the ATO's money the moment it lands in your account. Sweep it into a separate account every week, lodge each BAS by its due date even when you cannot pay all of it, and check your cash position ahead of every deadline. If a debt does build, get the lodgement in first, then sort out the balance with instalments or finance.
Key points
- GST and PAYG withholding belong to the ATO, not the business
- A dedicated tax account and weekly sweeps stop nasty surprises
- Lodge by the due date every time, paid or not
- Move quickly if a BAS balance starts to grow
How sound businesses end up owing on BAS
Each sale brings GST in with it, and each pay run holds back PAYG withholding. That money then sits for weeks in the everyday account, indistinguishable from everything else. A supplier invoice arrives, a customer pays late, the team is flat out, and the cash that was always earmarked for the ATO quietly goes on keeping the business running. By the time the BAS falls due, it has gone. That is not carelessness. It is simply what happens when tax money and trading money share a single bank account.
Give the tax money its own home
The easiest system is a separate tax account. Here is how to run it:
- Set up a second business account whose only job is holding tax.
- Once a week, move across the GST you collected, minus the credits on your purchases, plus the PAYG withheld from wages.
- If you want super ring-fenced as well, park it there too.
- When a BAS falls due, pay it straight out of that account.
- Never dip into the tax account for anything else.
Some owners skip the calculation and transfer a fixed slice of every deposit instead. It is less exact, but it works remarkably well.
Key dates through the year
| Obligation | When it usually falls |
|---|---|
| Quarterly BAS | The 28th of the month after each quarter, except the December quarter, which is due 28 February |
| Monthly BAS | Each month, mainly for larger businesses |
| PAYG withholding | Reported and paid through your BAS |
| Super guarantee | With each pay run under Payday Super, from 1 July 2026 |
| Income tax | After the financial year ends, with instalments for some businesses |
A registered tax agent may have later lodgement dates. The ATO’s BAS due dates page shows which apply to you.
Lodge by the due date, no matter what
Can’t pay the full BAS? Lodge it on time regardless. That tells the ATO the true figure, avoids penalties for failing to lodge and, where PAYG withholding is involved, keeps valuable director penalty options open. An unlodged BAS hides the real position from the ATO and from any lender you speak to. If you are already behind, read behind on BAS.
Check the numbers before each deadline
A fortnight out from each BAS, compare what is in the tax account with what you expect to owe. If there is a gap, you still have time to fix it: chase overdue invoices, hold off on a purchase you can delay, or speak to the ATO about instalments. The cash flow gap calculator shows how the BAS payment will affect the months ahead.
When a balance builds regardless
Even disciplined businesses sometimes fall behind. Once you have lodged, you can ask the ATO for instalments or pay the balance with finance. Our comparison of an ATO payment plan with a business loan helps you choose. Overdue tax usually attracts interest, so acting sooner generally costs less.
Let a bookkeeper carry the load
A capable bookkeeper can reconcile GST every week, work out the transfer, warn you about shortfalls and get each BAS lodged on time. Their fee is normally small next to the penalties, interest and stress that come with a growing tax debt.
Don’t forget income tax
BAS is only one part of the picture. Profitable businesses, especially sole traders and partnerships not paying PAYG instalments, can face a large income tax bill after 30 June. Our EOFY cash flow planning guide explains how to prepare.
An illustrative example
During a rapid growth phase, a Hobart landscaping company slipped three BAS payments behind. It cleared the balance with an unsecured loan, and the owner then opened a tax account with an automatic weekly transfer of a set share of deposits. A year later every BAS had been paid in full and on time, and the clean tax record helped the business qualify for a better-priced facility.
Clear the old balance
If a BAS debt is already growing, enquire in a minute. There is no credit check when you first enquire, a person reviews it, and your details are never sold as a lead. Clear your BAS debt.
Frequently asked questions
How much should I set aside for GST?
Put aside the GST built into your sales, minus the GST credits on what the business buys. Your accounting software or bookkeeper can work out the weekly figure.
When is quarterly BAS due?
For most businesses lodging themselves, each quarterly BAS is due on the 28th of the month after the quarter ends, except the December quarter, which is due on 28 February. Tax agents often get later dates. The ATO due dates page linked below lists them.
Should PAYG withholding go in the tax account too?
Yes. Tax withheld from wages has to be paid to the ATO, and if it goes unpaid it can expose directors to penalties.
What about super?
Since 1 July 2026, Payday Super means employers pay super with each pay run so it reaches funds within seven business days. Putting it aside alongside your tax money helps avoid the super guarantee charge.
What if I already owe on BAS?
Get any outstanding statements lodged first, then look at an instalment arrangement or finance to clear the balance.
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