Instalment Activity Statement (IAS): What It Is, Who Lodges One, and When

What an instalment activity statement is

An instalment activity statement is the activity statement for taxpayers whose reporting obligations are PAYG income tax instalments, PAYG withholding or fringe benefits tax instalments, and who have no GST to report. It is the same machinery as a BAS with the GST half removed.

The ATO does not publish a prose definition of the term. Its only dedicated IAS page is a table of approved forms, last updated 25 March 2026, whose description line runs to one sentence: "Access instalment activity statement approved forms." So the definition has to be read off the forms themselves, and that reading is unambiguous. Every one of the five approved IAS forms covers PAYG instalments, PAYG withholding or FBT. None of them lists a GST obligation.

The legislative hooks are in Schedule 1 to the Taxation Administration Act 1953: sections 45-205 and 45-210 for instalments, and subsection 16-150(1) for the obligation to notify withheld amounts. IAS J picks up sections 102, 104 and 112A of the Fringe Benefits Tax Assessment Act 1986 on top.

What an activity statement is

Activity statement is the ATO's umbrella term for the form you use to report and pay several taxes at once, on a set cycle. It is a container, not a single tax. What appears inside it depends on what you are registered for.

The container comes in three shapes, and the names get used loosely everywhere except on the ATO site:

• Business activity statement (BAS). The GST version. The ATO lists its sections as GST, PAYG instalments, PAYG withholding, FBT instalment, luxury car tax, wine equalisation tax and fuel tax credits.
• Instalment activity statement (IAS). The same form minus the GST, WET, LCT and fuel tax credit labels. PAYG instalments, PAYG withholding and FBT only.
• Instalment notice. A pay-only document. It carries a pre-printed amount and, unless you are varying it, you pay it rather than lodge it.

One point of ATO wording that trips people up: the label "BAS" gets applied to the whole family in places. The sample IAS J form on ato.gov.au is titled "IAS J - Quarterly instalment activity statement", and its own download link reads "BAS J". That is an ATO labelling slip rather than a meaningful distinction, and it is worth knowing about if you go hunting for the sample PDF.

Who lodges an IAS instead of a BAS

GST registration is the switch. The ATO puts the BAS side plainly: "If you are a business registered for GST, you need to lodge a business activity statement (BAS)." It follows on to say that "when you register for an Australian business number (ABN) and GST, we'll automatically send you a BAS when it is time to lodge." You do not choose the form. The registration chooses it for you.

Reading the approved forms table the other way gives you the typical IAS lodgers:

• Partners in partnerships and other individual taxpayers who pay a PAYG income tax instalment each quarter. That is the ATO's own description of the typical IAS B user.
• Employers who withhold from wages but have no GST obligation, on a quarterly, monthly or annual withholding cycle. That is IAS I.
• Taxpayers carrying instalments, withholding and an FBT instalment together, which is IAS J.
• Taxpayers who elected to pay one annual PAYG instalment, which is IAS N.

There is a fourth group that catches people out, because it puts an IAS in the hands of a business that does lodge a BAS. The ATO states that a client with no monthly GST obligation who is registered for monthly PAYG withholding or monthly PAYG instalments, and who has at least one quarterly obligation, receives "a monthly activity statement for the first 2 months of the quarter" and "a quarterly activity statement for the third month". The IAS I form description carries the same note. Three statements in one quarter, and two different due dates.

IAS vs BAS, side by side

The difference between a BAS and an IAS is GST, and nothing else is a reliable test. Both can carry PAYG withholding. Both can carry PAYG instalments. Both can carry an FBT instalment. Only the BAS carries the GST labels.

The one row worth sitting on is Other taxes. Plenty of summaries describe the IAS as "the PAYG statement", which is close enough to be useful and wrong enough to matter, because IAS J carries an FBT instalment as well. A statement is an IAS because it has no GST section, not because it is limited to PAYG.

The five IAS forms the ATO approves

The ATO's approved forms list is the most precise answer available to the question "who lodges an IAS", because each row states its intended user. These are the ATO's descriptions, condensed.

Source: ATO, Instalment activity statement approved forms, fetched 31 July 2026, page last updated 25 March 2026. The sample PDFs are for record keeping and cannot be lodged. Note that the ATO URL without the approved-forms path segment now returns a 404.

The labels on an IAS

An IAS has two label blocks that matter: the W block for withholding and the T block for instalments. What you fill in depends on which obligations you carry, and on your choice to vary or not.

PAYG withholding: W1 to W5

• W1, total salary, wages and other payments. Gross payments you made from which you are usually required to withhold. Salary, wages, allowances and leave loading, director fees, office holder pay, labour hire payments, employment termination payments, payment for unused annual or long service leave, super income streams and lump sums, and attributed personal services income. Report the payment even if you withheld nothing from it. Leave out salary sacrificed amounts, super contributions and anything that belongs at W4.
• W2, amounts withheld from the payments at W1. The ATO calls this the main type of withholding, and says that if you have no other withholding obligations you can go straight from W2 to W5.
• W4, amounts withheld where no ABN is quoted. Where a supplier does not quote an ABN you withhold 47% of the invoice amount, a rate in place since 1 July 2017.
• W3, other amounts withheld. No-TFN investment distributions, interest, dividends or royalties paid to a foreign resident, departing Australia superannuation payments, and payments to foreign residents for entertainment and sport, construction, or casino gaming junkets.
• W5, total amounts withheld. W2 plus W4 plus W3. W1 does not go into W5.

Two more rules change what you fill in. If you report through Single Touch Payroll, the ATO says you no longer need to report amounts at W1 on your activity statements. And a large withholder, meaning one that withheld more than $1 million in a previous income year, completes W1 only and leaves W2, W3, W4, W5 and label 4 alone.

PAYG instalments: the T labels

Which T labels you touch depends on which option you are on. Option 1 is paying the amount the ATO worked out. Option 2 is multiplying your instalment income by a rate the ATO gives you.

The ATO's own worked example on option 2 is the fastest way to see the arithmetic. Sophia is a sole trader. Her quarter brings in $22,000 of sales including $2,000 of GST, plus $100 of interest and dividends. Her instalment income is $20,100, so she enters 20,100 at T1. Her rate at T2 is 1.7%. T1 times T2 gives $20,100 × 1.7% = $341.70. She enters 341 at both T11 and 5A, lodges the statement and pays $341 by 28 October.

Claiming a credit at 5B is optional. The ATO is explicit that you can leave it and let the credit fall out in your tax return instead, where instalments are credited against your income tax liability, any excess is refunded and any shortfall is paid.

How often you lodge

There is no single IAS cycle. The frequency is set separately by your withholding cycle and by your instalment cycle, and if you carry both you take the more frequent of the two.

Withholding. The ATO sets your withholder status off your annual withholding amount. At $25,000 or less you are a small withholder and notify and pay quarterly. Above $25,000 and up to $1 million you are a medium withholder and notify and pay monthly. Above $1 million you are a large withholder, which takes you out of the statement cycle for payment purposes: you pay electronically within six to eight days of a withholding event, such as a pay run, against a unique payment reference number.

Instalments. Most taxpayers pay quarterly. The ATO may offer two instalments a year or one annual instalment depending on your circumstances, and businesses with instalment income above $20 million must lodge and pay monthly. The two-instalment option is narrow: it is open to quarterly instalment-amount payers who are individuals carrying on a primary production business, or special professionals such as authors, inventors, performing artists, production associates and sportspeople, and it runs 75% by 28 April with the balance by 28 July.

The annual instalment sits slightly outside all of this. If you prepare and lodge your own tax return the ATO says you do not need to lodge the instalment notice or pay the annual instalment, you just lodge your return by 31 October. If a tax agent lodges for you, pay the annual instalment by 21 October and pay it before the return goes in, so the credit lands in the right assessment. Eligibility to pay annually turns on notional tax under $8,000 and on not being required to register for GST, which is the same GST line that decides IAS against BAS in the first place.

IAS due dates for 2026-27

Monthly activity statements are due for lodgment and payment on the 21st day of the following month. Quarterly activity statements are due on the 28th day of the month after the quarter, except quarter 2, which is due 28 February because that date already carries a one-month extension.

These are the ATO's published 2026-27 tables. The generate date is when the statement is produced; online statements are generally available a week later, and posted ones can take up to three weeks.

The monthly ladder for 2026-27 runs the same way all year. July 2026 is due 21 August 2026, August is due 21 September, September is due 21 October, and so on through to June 2027, which is due 21 July 2027. Where a legislative due date falls on a weekend or public holiday it moves to the next working day.

Two concessions are worth knowing about, and one of them does not apply to everyone. Lodging an activity statement online can earn an extra two weeks to lodge and pay, but the ATO states that a taxpayer paying GST monthly is not eligible for it, and quarter 2 never gets it because 28 February is already extended. The agent lodgment program dates in the last column are the registered agent equivalents, and a quarterly statement drops out of them if it carries a monthly PAYG instalment obligation, if it is a consolidated head entity statement, if the entity is on a monthly GST cycle, or if it is a form R, S or T instalment notice.

The federal date ladder across withholding, instalments and returns sits in when PAYG is due. If you have already missed one, read missed PAYG instalments before you do anything else.

The IAS and the PAYG instalment notice

The quarterly PAYG instalment notice, form R, is one of the ATO's five approved IAS forms, so the notice sits inside the IAS family administratively. What separates it is not the content, it is what you have to do with it.

The ATO sets out a three-part test for receiving a notice instead of a statement. You get one if you:

• report and pay your GST or PAYG instalments quarterly
• pay using the instalment amount advised by the ATO, which is option 1
• have no other reporting requirements.

The notice shows a PAYG instalment amount at T7, and a GST instalment amount at G21 where that applies. If you pay the amount shown, you do not lodge it. The ATO is direct about this: "If you receive your notice by post, you don't need to send the notice to us with your payment. Keep the instalment notice for your records." Lodgment is only required if you are varying.

The third bullet is the one that does the work. Add any other reporting obligation, such as PAYG withholding on staff wages, and the ATO issues a statement rather than a notice, because now there is something to report rather than only something to pay. Switching options has the same effect in reverse: the ATO tells agents that a client who received a form R or T in quarter 1 and wants to move to the instalment rate option should make contact before 28 October, after which the ATO will "send a new instalment activity statement for lodgment".

If a notice turned up unexpectedly and you are not sure why the ATO put you into instalments at all, that is covered in why you got a PAYG instalment notice.

Lodging it, and when you do not have to

The rule is short. If you receive an activity statement, complete it and lodge it. If you receive an instalment notice and are paying the amount shown, pay it and keep the notice. If you want to vary, or you need to correct an earlier instalment, you lodge either way.

Lodging online is the ATO's default route: myGov linked to the ATO for individuals and sole traders, Online services for business, Standard Business Reporting enabled software, or a registered tax or BAS agent. The paper route still exists, and paper statements go to the Australian Taxation Office, Locked Bag 1936, Albury NSW 1936. If you lodge online with an email address on file, the ATO sends a reminder 21 days before the due date.

On nil statements, note what the ATO actually publishes and where. The nil rule appears on the BAS page: "Even if you have nothing to report for the period, you still need to lodge your BAS as ‘nil’ by the due date." The ATO does not publish separate nil wording for the IAS. The safe reading is the obvious one: a statement that has issued to you is a statement to lodge, so lodge it as nil rather than leaving it open. Nil lodgment can be done online or through the automated phone service on 13 72 26, though the phone service is closed to statements carrying a pre-printed amount or rate greater than zero at F1, G21, T2, T7 or 7A.

One practical note for employers who look at W1 and see nothing to do. Reporting through Single Touch Payroll removes the W1 requirement from your activity statements, which is one of the more common reasons a withholding-only IAS looks emptier than expected. The wider employer picture sits in PAYG withholding and registering for PAYG withholding.

Frequently asked questions

Sources

Every form description, label definition and date on this page was fetched from ato.gov.au on 31 July 2026. The 2026-27 quarterly and monthly tables come from the ATO page that labels them "2026-27 financial year", so the year label is the ATO's rather than ours. The ATO does not publish a page defining the phrase "instalment activity statement"; its only dedicated IAS page is the approved forms list below, and the definition on this page is read off those five form descriptions.

Related resources

Narelle Hartigan, CPA Verified Expert

Tax Accountant & PAYG Specialist

Narelle Hartigan is a CPA-qualified tax accountant with over a decade of experience in Australian personal taxation and payroll. She founded PAYG Calculator Australia to make tax withholding easy for every Australian worker to understand.

CPABCom (Accounting)

Published: 31 July 2026 · Updated: 31 July 2026