Tax time cash flow: build the money before the bill arrives

A tax bill never feels like a surprise on the day the ATO sends it. It feels like a surprise because the money was never separated from the rest of the cash while the business was earning it. Everything in the account looked like yours.

This guide is about building the habit that fixes that, and about the specific traps that catch Australian small businesses in the 2026-27 year, including some that are brand new.

Why does tax time hurt even when the business is doing fine?

Because “tax” is not one payment. A typical owner faces at least four separate cash events across the year, each with its own calendar.

Cash event	What drives it	When it lands
BAS: GST and PAYG withholding	Sales and wages in the period	Monthly or quarterly, around the 21st to 28th
PAYG instalments	An estimate based on your last assessed year	With the activity statement
Super	Wages paid	Now every pay cycle, under Payday Super
Income tax balance	Actual profit for the year, less instalments paid	After you lodge your return

Each is manageable alone. The damage comes when two land in the same fortnight, which they do more often than people plan for. The October quarter is a clear example: the first activity statement of the new financial year is due on 28 October 2026, just as the next payroll runs and perhaps before the Christmas stock has been paid for.

What does the money actually look like in a normal month?

An invented but realistic example. A Brisbane electrical contractor takes $64k in a month, including $5,800 of GST. Wages run to $21k, which means PAYG withholding of around $3,900 and super on top. Materials cost $18k. The owner’s gross profit looks healthy at the end of the month.

But the bank balance includes money that never belonged to the business:

• $5,800 of GST collected, less the GST paid on materials. Say $3,900 net.
• $3,900 of PAYG withholding.
• Super, now leaving each pay cycle.
• A slice of profit that will be taxed at the end of the year, perhaps 20 to 25 per cent of it.

If the owner spends the month’s closing balance as though it were all profit, the business has borrowed from the ATO without agreeing to. Do that for six months and you have a debt, not a business with a bad quarter.

How do you set money aside without thinking about it?

The best systems are boring. They happen without a decision.

1. Open a separate tax account. A second business account at your bank is enough. Name it “tax” so it reads as untouchable.
2. Move the GST and PAYG shares on pay day. When a customer pays, move the GST portion across. When payroll runs, move the PAYG withholding. Accounting software can show you the exact figure at any time.
3. Ask your accountant for one percentage. Not a final number. A rate to apply to profit each month so that the year-end balance is mostly pre-funded. Review it each quarter, because the right number moves as the year unfolds.
4. Sweep weekly. A small regular move beats a large occasional one, and it shows up in cash flow forecasts so you can see the real position. Our guide to GST cash flow tips shows the weekly routine step by step.
5. Never pay a creditor from the tax account. The moment you do, it becomes a spending account.

Most businesses that set this up find two things. The first quarter feels tight, because they are funding a cost that used to be deferred. After that it settles, and the end-of-year bill stops being news.

What is the PAYG instalment trap?

PAYG instalments are the ATO’s way of collecting income tax during the year. The amount is based on an earlier assessed year, which is why a business that has grown quickly can end up owing a large balance after it lodges: instalments paid were based on a smaller year.

The reverse also matters. If profit has dropped, you can vary the instalment downwards to preserve cash. That is allowed, but the risk is real. When the amount you varied to falls well short of the tax you finally owe, the ATO can charge general interest charge on the shortfall, and since 1 July 2025 that interest cannot be claimed as a deduction. Treat a variation as a forecast you are prepared to defend, not a way to ease this month’s pressure.

The government has also announced, as a budget measure that was not yet law at the time of writing, plans from 1 July 2027 to let eligible small and medium businesses opt in to monthly PAYG reporting and to use ATO-approved calculations built into accounting software, with interest removed where an approved calculator was used and got it wrong. If it passes, it should make variations safer. Until then, keep your own forecast.

How does Payday Super change the tax-time picture?

For years, many employers held super for up to a quarter. That float was, in effect, free working capital. From 1 July 2026 super must reach the employee’s fund within 7 business days of each payday, so the float is gone. In the first quarter after the change, some employers had both the final quarterly payment and the new per-payday payments to find. The full detail is in our guide to super guarantee obligations and cash flow.

The tax-time consequence is that your cash buffer needs to be a little bigger than it used to be. The money has not changed. It simply leaves earlier.

What if the bill is bigger than the cash?

Do not wait until the due date. Your options, roughly in order of how early to act:

• Lodge on time regardless. This keeps every later option open, including payment plans and, for company directors, more favourable treatment if a notice ever arrives.
• Talk to your accountant about timing. Legitimate planning can shift deductions and income across years, and your adviser may know about concessions that apply.
• Ask the ATO for a payment plan. Our guide to ATO payment plans explains what is possible and what it costs.
• Consider finance for the gap. Banks are often the cheapest option, and a profitable, lodged business may find a bank willing to help. If the bank cannot, specialist lenders can fund tax bills. See funding for a tax bill for the options.

A cash flow gap that arrives once a year is a very different problem from a business that is short every month. Be honest about which one you have, because they need different fixes.

If you are working through the year-end, the end of financial year checklist and key dates in the tax calendar are useful companions.

Common mistakes at tax time

• Treating the bank balance as profit. Always net off GST, PAYG and super first.
• Using the tax account for a bad week. One raid and the system collapses.
• Varying instalments to the floor. It saves cash now and costs interest later.
• Ignoring a large one-off sale. A big job lifts profit, and tax follows it. Set aside on the day the invoice is paid.
• Lodging late because you cannot pay. Late lodgement is the thing that closes doors.
• Leaving the accountant out of the quarter. A call each quarter costs little. A surprise costs a great deal more.

A short, practical bridge to the next step

If you are looking at a bill you cannot cover, or you want to know what finance would look like before you decide, tell us what is coming. A short enquiry is a sensible way to see how the numbers might work.

When the bill is bigger than the balance

Lots of good businesses reach tax time short. A strong year that has pushed everything into stock, equipment or growth is a good reason, not a failing. What matters is acting while you still have choices.

If you would like to know what finance might look like for a tax bill, we are happy to look at it. Asking takes around a minute, and your credit file stays untouched by the enquiry. Your details are not shopped around, so there is no run of calls from strangers. A person here reads your situation, then calls you. If you can, say how much is owed, when it is due and whether everything is lodged. That lets us start from the option most likely to fit.

See what could cover my tax bill →