IAS explained: what it is and who lodges one
Jamee White, CPA5 min readThink of an IAS as a BAS with the GST section quietly removed. It's the form the ATO issues when you've got PAYG amounts to report but a full BAS isn't required for that period: most commonly, employers remitting PAYG withholding monthly while their BAS stays quarterly, or taxpayers paying PAYG income tax instalments who aren't registered for GST. What follows is what it actually is, who gets one, and when it's due.
What an IAS actually is
Delete the GST section from a BAS and you've basically got an IAS: an activity statement lodged with the ATO reporting things like PAYG withholding from employee wages and PAYG income tax instalments. No GST means no complexity, usually just one or two figures to fill in.
Most of the confusion is naming, honestly. People hear BAS and IAS thrown around interchangeably and assume they're the same document. They're related, sure, but the IAS exists specifically for the periods or taxpayers where GST reporting doesn't come into it at all.
Who lodges an IAS
- Employers whose PAYG withholding is paid monthly while their BAS stays quarterly; they lodge an IAS for the first two months of each quarter, then report month three on the BAS
- Individuals or entities paying PAYG income tax instalments without a GST registration, such as some investors and trusts
- Businesses that deregistered for GST but still carry PAYG obligations
- Anyone the ATO has placed on monthly instalment reporting for other reasons
The two months on IAS, one month on BAS pattern is what trips people up most. Become a medium withholder because your annual withholding has grown, and your PAYG obligations go monthly while GST stays quarterly. Miss a monthly IAS in that setup and you fall behind fast.
When an IAS is due
Monthly activity statements, IAS included, are generally due by the 21st of the following month. July's IAS, for instance, is due 21 August. Unlike quarterly BAS lodgments, the monthly deadline usually doesn't come with an extended agent date, which is exactly why it catches people out.
If your IAS just reports a pre-printed PAYG instalment amount and you're happy to pay it as issued, the whole process is as simple as paying by the due date. Want to vary the instalment because your income's changed? That takes more care, and it needs doing on time.
How the IAS fits into your bookkeeping rhythm
Treat the IAS like any other deadline: the figures should come straight out of a reconciled payroll and a clean ledger, not a last minute scramble. Payroll processed properly each cycle means the withholding figure already sits in your software, and lodgment takes minutes. Problems show up when corrections, bonuses or out of cycle pays haven't been recorded before the statement gets prepared.
It's also worth reconciling what's been reported across IAS and BAS against your payroll records at least once a quarter. Small mismatches add up quietly, and they tend to surface at year end when income statements get finalised.
Where NextEra fits
Monthly IAS obligations are exactly the sort of quiet deadline that slips when bookkeeping happens in fits and starts. NextEra's managed monthly bookkeeping keeps payroll reconciled and every activity statement built from clean data, and a Strategic Finance Review will quickly tell you whether your current lodgment cycle still fits the size of your business.
Quick answers
A BAS reports GST plus other obligations like PAYG withholding and instalments. An IAS reports those same PAYG amounts minus the GST section.
This article is general information for Australian businesses, current at the published date. It is not financial, tax or legal advice. Speak to a registered agent or adviser about your circumstances before acting.
Jamee White, CPA
Founder of NextEra Bookkeeping. Jamee leads a team supporting established Australian businesses with strategic bookkeeping, reporting, payroll and Xero, and is a multiple national awards finalist across bookkeeping and finance.