PAYG Instalments Australia: How the ATO System Works

PAYG instalments are regular prepayments toward the income tax on your business and investment income, so you pay it across the year instead of in one bill after you lodge. The ATO enters you into the system automatically once a tax return shows enough business or investment income, then sends you a quarterly amount or rate. This guide covers who gets entered, the two ways each instalment is worked out, when they fall due, how to vary one without copping interest, and how the instalments credit against your final assessment.

If you are an employee, tax already comes out of your pay through PAYG withholding. PAYG instalments are the equivalent for income that reaches you untaxed: the profit from your sole trader business, rent, dividends, and other investment income.

What PAYG instalments are

When you earn a wage, your employer withholds tax from each pay and sends it to the ATO, so you rarely face a large bill at tax time. Business and investment income arrives untaxed. Without a prepayment system, a sole trader earning a decent profit would face the whole year's tax as a single lump sum months after the money was already spent.

PAYG instalments spread that load. You pay an estimate of this year's tax in quarterly (sometimes monthly or annual) chunks, based on what your last return showed. The ATO treats the instalments as prepayments: they are not an extra tax, and they are separate from PAYG withholding on wages. When you lodge, everything you paid is credited against your actual tax, and any gap is settled either way.

One term does a lot of work here. Your instalment income is your gross business and investment income for the period, before expenses, excluding GST you collected and any capital gains. It is the figure the rate method multiplies against, so it is worth understanding before you choose a method.

Who has to pay PAYG instalments

You do not opt in. The ATO reviews each return you lodge and enters you automatically once your numbers cross the entry thresholds. The test differs for individuals and companies.

An individual has to meet all three conditions, so a small side income on its own will not pull you in. Once you are in, the ATO notifies you and pre-fills your activity statement or instalment notice. You can also enter voluntarily to smooth a tax bill you can see coming, which is common in the first profitable year of a sole trader business before the ATO has a return to trigger entry.

The starting rules also set your payment frequency. Most people pay quarterly. You move to monthly instalments only if your instalment income was $20 million or more (a threshold few sole traders reach), and you may qualify to pay a single annual instalment if your notional tax was under $8,000 and you are not registered for GST.

The two ways each instalment is worked out

The ATO offers two methods, shown as Option 1 and Option 2 on your activity statement. You pick one for the year.

Option 1, the instalment amount, is the low-effort path. The ATO takes the tax from your most recent assessment, lifts it by the GDP adjustment factor to reflect likely income growth (4% for the 2025-26 income year, 5% for 2026-27), and splits the result across your quarters. Say the uplifted figure is $12,000. You pay $3,000 a quarter, the same number every time, regardless of what you earned in those three months.

Option 2, the instalment rate, tracks your real income. The ATO gives you a rate, and you multiply it by your instalment income for that quarter. If the rate is 11% and you earned $30,000 in the quarter, you pay $3,300. Earn $18,000 the next quarter and you pay $1,980. The payment rises and falls with the business, so a slow quarter brings a smaller payment, not an overpayment. The trade-off is that you have to know your gross income for each quarter, which means keeping your books current rather than reconstructing them in a panic on the 27th.

The ATO calculates both figures from the same past return, so neither method is inherently cheaper. The choice is about how well a fixed number fits an income that may not be fixed.

When PAYG instalments are due

Quarterly instalments are due 28 days after the end of each quarter, with one shift over the summer holidays.

If a due date lands on a weekend or public holiday, you have until the next business day. Monthly payers report by the 21st of the following month. If you pay a single annual instalment, it is due on 21 October, after the income year has ended.

If you are registered for GST and lodge a business activity statement, your PAYG instalment usually sits on the same BAS and shares its due date, so the two obligations move together. Sole traders who report GST quarterly effectively handle both in one lodgment.

How to vary an instalment without triggering interest

The ATO's pre-filled amount looks backward, at last year's income. If this year is clearly different, you can vary an instalment up or down through your activity statement. Varying down when a contract ended or the business slowed can free up real cash, but it carries a trap that catches people who guess optimistically.

The rule is the 85% test. If your varied instalments for the year come to less than 85% of the actual tax payable on your business and investment income, the ATO can charge the general interest charge on the shortfall, and there may be penalties on top. The test applies whether you varied the instalment amount or the rate.

Here is how it bites. Suppose your tax on business and investment income for the year turns out to be $16,000 when you lodge. The 85% mark is $13,600. If you had varied your instalments down to $10,000 across the year, you paid $3,600 under that mark, so the ATO can add interest on the gap. For the July to September 2026 quarter the general interest charge runs at an annual rate of 11.43%, and since 1 July 2025 that interest is no longer deductible, so it costs you more than the headline rate suggests.

The safe approach is to vary down only when you have the records to back the lower figure, not on a hunch. If you use the instalment rate method, you rarely need to vary at all, because the payment already falls when your income does. You would vary the rate only if the taxable proportion of your income changed, for example after a large new deduction like the instant asset write-off.

How your instalments credit against the final tax bill

PAYG instalments are prepayments, not a final tax, so nothing is settled until you lodge. You do not enter the instalments anywhere in your tax return. The ATO automatically credits every instalment you paid during the year against the tax on your assessment.

The maths is simple. Add up the tax on your total income for the year, subtract the instalments already paid, and the difference is what happens next:

• Instalments came to less than your final tax: you pay the shortfall.
• Instalments came to more than your final tax: the ATO refunds the excess.

Because of this, finalising any outstanding instalment before you lodge matters: it ensures the full credit shows up in your assessment and you are not billed for tax you have effectively already paid. Lodging your income tax return, covered in our guide to the Australian tax return deadline, is the moment the whole year reconciles.

How SparkReceipt helps

SparkReceipt does not calculate your PAYG instalments or lodge your activity statement, and no app should claim to decide your tax for you. What it does is keep the numbers those decisions rest on current and clean.

Because the instalment rate method multiplies against your gross business income each quarter, you need that figure without digging through a shoebox. SparkReceipt's expense tracker records your income and expenses as they happen, so your instalment income for the quarter is a report, not a reconstruction. When you are deciding whether to vary, a one-click expense report gives you and your accountant the quarter's real position instead of a guess. Good records are also what the ATO expects you to keep behind every figure on an activity statement. You can see the plans to find the fit for your business.

Frequently asked questions

Why do I suddenly have to pay PAYG instalments? Your last tax return crossed the entry thresholds. For an individual that means instalment income of $4,000 or more, tax payable of $1,000 or more, and notional tax of $500 or more, all together. The ATO enters you automatically and notifies you; you did not miss a form.

Are PAYG instalments an extra tax? No. They are prepayments of the tax you would owe anyway on your business and investment income. Every instalment is credited against your final assessment when you lodge, so you are paying the same tax earlier, not paying more.

Can I opt out of PAYG instalments? The ATO removes you automatically once a return shows business and investment income under $4,000 or a tax debt under $1,000. If you have stopped earning business or investment income, you can also ask to exit through ATO online services, your registered tax agent, or by phoning the ATO. If a later return crosses the thresholds again, you re-enter.

What happens if I do not pay an instalment? The unpaid amount attracts the general interest charge until it is paid, at 11.43% a year for the July to September 2026 quarter, and that interest is not deductible. The instalment does not disappear: it still credits against your assessment, but the interest is a real cost on top.

Should I choose the instalment amount or the instalment rate? Pick the instalment amount if your income is steady and you want zero calculation each quarter. Pick the instalment rate if your income swings, because the payment moves with your actual earnings and you avoid overpaying in a slow quarter. Both come from the same past assessment.

Key takeaways

• PAYG instalments prepay the tax on your business and investment income in quarterly (sometimes monthly or annual) amounts, and they are separate from PAYG withholding on wages.
• The ATO enters an individual automatically when a return shows instalment income of $4,000 or more, tax payable of $1,000 or more, and notional tax of $500 or more, all three together.
• Option 1 pays a fixed dollar amount uplifted by the GDP factor (5% for 2026-27); Option 2 applies a rate to your actual quarterly income, so it self-adjusts.
• Quarterly instalments fall due on 28 October, 28 February, 28 April, and 28 July, shifting to the next business day over weekends and holidays.
• Vary down only with records behind the lower figure: instalments under 85% of your actual tax attract the general interest charge (11.51% a year for October to December 2026, non-deductible) on the shortfall.
• Nothing is final until you lodge, when every instalment is credited against your assessment and the difference becomes a bill or a refund.