Getting Your Cash Flow Ready for the October BAS
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Your first BAS of the financial year is due on 28 October. For a lot of businesses it's the hardest one of the four.
July and August are quiet months. Clients take longer to pay. Then September ends, the quarter closes, and you're looking at a GST bill built on invoices you sent months ago and haven't been paid for yet.
The ATO wants the GST on those invoices whether or not the money has landed. That's the part that catches people out.
Why the September quarter hurts more than the others
If you report GST on an accrual basis, you owe it when you issue the invoice, not when the customer pays. Do $200,000 of work in the quarter and you're carrying roughly $20,000 in GST regardless of what's actually in your account on 28 October.
Add PAYG withholding for your staff, and PAYG instalments if you pay them, and the number gets uncomfortable quickly.
Now think about who owes you money right now. Most trade and service businesses are carrying 60 to 90 day terms with their larger customers. Work you finished in July might not be paid until October. Your BAS doesn't wait for that.
There's a second problem specific to this quarter. Plenty of businesses paid a large tax bill in July after lodging their FY26 return, then went straight into a slow August. By the time October arrives, the buffer is gone.
Work out the number before October
The worst version of this is finding out what you owe three days before it's due.
Pull your figures now, at the start of September. You need four things:
- GST collected on sales for July, August and the first part of September
- GST paid on purchases, which comes off what you owe
- PAYG withholding on wages for the quarter
- Your PAYG instalment if the ATO has issued one
Your accounting software will give you a running total. It won't be exact until the quarter closes, but you'll be within a few thousand dollars, which is enough to plan against.
Then check that number against your aged receivables. If you owe $25,000 and you have $80,000 in invoices due before 20 October, you're fine, assuming those customers pay on time. If most of your receivables are sitting in the 60+ day column, you have a timing problem, and you have seven weeks to sort it out rather than three days.
If the money is there but not yet
This is the situation most businesses find themselves in. Profitable quarter, real invoices, no cash in the account when the bill falls due.
A few options, roughly in order of how much they cost you.
Chase what's overdue. Obvious, but most businesses are softer on this than they should be. Anything past terms gets a call this week, not an email. A polite phone call to accounts payable moves an invoice up the queue more reliably than anything else you can do.
Ask for a payment plan. The ATO will usually agree to one if you contact them before the due date. Lodge on time even if you can't pay in full, because the penalties for late lodgment and late payment are separate. Interest still accrues, but you avoid the failure to lodge penalty.
Finance the receivables. If the cash is genuinely tied up in invoices your customers haven't paid yet, invoice finance releases up to 80% of that value within 24 hours. You're not borrowing against the business or taking on a loan you'll be servicing for years. You're getting paid earlier for work you've already done.
That last one suits the BAS problem specifically, because the timing lines up. The GST you owe relates to invoices you've issued. Those same invoices are the asset you're drawing against.
Lodging online buys you time
If you lodge your own BAS online you may get an extra two weeks. Lodging through a registered BAS or tax agent can give you longer again.
Worth knowing, and worth not relying on. An extension moves the date. It doesn't change whether the money is there.
The habit worth building
Businesses that never seem stressed about BAS aren't earning more than everyone else. They've usually just separated the tax money from the operating money.
Some open a second account and move the GST across as invoices are paid. Some keep a fixed percentage aside. The method doesn't matter much. What matters is that the money stops feeling available for other things.
Start that in October, once this quarter is behind you. It makes the January BAS considerably easier, which is useful given it lands right after the December slowdown.
The short version
Work out what you owe now, not in late October. Compare it against what your customers owe you and when they're likely to pay. If there's a gap, you have weeks to close it, which is a very different situation to finding out on the 25th.
If your cash is sitting in unpaid invoices and the BAS is due before your customers pay, invoice finance can bridge that gap. Brunswick advances up to 80% of your invoice value within 24 hours.