IAS (Instalment Activity Statement) in Australia – When It Applies, What to Report & How to Lodge

IAS

Understand what an IAS is, how it differs from a BAS, who needs to lodge it, and how Ozobooks supports accurate IAS lodgements and PAYG compliance.

An Instalment Activity Statement (IAS) is a monthly form submitted to the Australian Taxation Office (ATO) by businesses or individuals who are not registered for GST but need to report and pay PAYG withholding or PAYG instalments.

While BAS includes GST and more, the IAS is used when only income tax instalments or employee tax withholding apply. At Ozobooks, we track due dates, prepare your IAS accurately, and lodge it on time to keep you compliant.

Who Needs to Lodge an IAS?

You may need to lodge an IAS if:

You’re not registered for GST, but
You withhold PAYG tax from wages, OR
You pay PAYG instalments as a sole trader, company, or investor

The ATO will notify you if you’re required to lodge an IAS.

What Is Reported in an IAS?

PAYG withholding (employee tax withheld)
PAYG instalments (income tax prepayments)
Fringe Benefits Tax (FBT) instalments (if applicable)

IAS vs BAS

Feature	IAS	BAS
GST registered?	No	Yes
Frequency	Monthly (usually)	Monthly or quarterly
Reports	PAYG, FBT (no GST)	GST, PAYG, fuel credits, FBT, WET, etc.
Lodgement form	Instalment Activity Statement	Business Activity Statement

Key IAS Due Dates

Most IAS are due by the 21st of each month for the previous month’s activity.

For example:

July IAS is due by 21 August
August IAS is due by 21 September

How Ozobooks Helps

Registers your business or sole trader for IAS (if required)
Calculates PAYG amounts correctly
Prepares and lodges monthly IAS on time
Keeps digital records for all ATO submissions
Helps with variation if income changes

FAQ:

Q1: Do I need to lodge both IAS and BAS?
Not usually. You either lodge BAS (if GST-registered) or IAS (if not). Some exceptions exist.

Q2: What if I miss an IAS deadline?
You may be fined or charged interest. Ozobooks helps avoid that.

Q3: Can I switch from IAS to BAS?
Yes, if you register for GST. Then BAS replaces IAS.

Q4: What if the ATO sends an IAS but I have nothing to report?
You must still lodge a nil IAS.