IAS Due Dates Australia: Instalment Activity Statement Guide
Understand IAS due dates in Australia and how accounting firms can manage PAYG instalments, client reminders and lodgement workflow.
This guide is written for Tax agents and accounting firms managing clients with PAYG instalment obligations. It explains how the obligation fits into Australian public practice, how firms can plan lodgement deadlines before they become urgent, and how client reminders, workflow ownership and practice management routines can reduce compliance risk.
Key dates and timing considerations
Due dates are only useful when the firm turns them into a working system. Australian accounting firms need to know the statutory or ATO lodgement deadline, but they also need earlier internal workflow dates for record collection, preparation, manager review, partner review, client approval and final lodgement.
- Monthly activity statements are generally due on the 21st day of the following month.
- Quarterly IAS dates often follow the quarterly activity statement cycle.
- Tax agent concessional dates can vary under the ATO lodgment program.
How to operationalise this inside an accounting firm
The most effective firms treat this topic as part of a wider compliance operating rhythm, not as an isolated date in a diary. A partner, director or manager should be able to open one view and see which clients are affected, which due dates are coming up, which reminders have been sent, which work is waiting on the client and which lodgements are at risk. That visibility is what turns a tax calendar into a practice management tool.
For public practice teams, the first step is to define ownership. Every client should have a responsible manager or staff member, and every recurring obligation should have a clear workflow path. That path normally includes information requested, information received, preparation started, manager review, partner review, client approval and lodged. Smaller firms may use fewer stages, but the principle is the same: the firm needs a shared language for progress.
Client communication
Client reminders should be specific, early and consistent. A useful reminder explains what the firm needs, when it is needed, what the client should do next and why the timing matters for ATO compliance or the relevant lodgement deadline.
Manager visibility
Managers need more than a list of dates. They need to know which clients have not responded, which jobs are unassigned, which obligations are approaching review and where workflow capacity is becoming tight across the team.
This is especially important when a firm is moving away from a spreadsheet. Spreadsheets can record due dates, but they rarely create reliable accountability. They do not automatically show whether a client reminder was sent, whether a manager changed, whether an email bounced, or whether a lodgement is still waiting for approval. A structured compliance workflow gives the team a better way to manage recurring deadlines without relying on memory or inbox archaeology.
What an IAS is used for
An Instalment Activity Statement, or IAS, is used for clients that need to report obligations such as PAYG instalments or PAYG withholding but may not be registered for GST. IAS work is often less visible than BAS work because it can feel simpler, but missed IAS lodgement deadlines still create compliance risk.
For accounting firms, the challenge is volume and consistency. A practice may have many clients with small IAS obligations, different reporting cycles and different expectations around reminders. Without a clear workflow, these jobs can disappear into inbox notes or spreadsheet rows.
For a public practice, the operational risk is rarely the date itself. The risk is that no-one owns the follow-up, the client reminder is sent too late, the manager cannot see what is stuck, or the team is using a spreadsheet that is no longer trusted. TaxCalendar is designed to connect due dates, client reminders, workflow ownership and compliance visibility in one place.
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IAS planning for tax agents
IAS work should be planned in the same way as BAS work: identify the due date, set an internal workflow date, decide when to contact the client and track whether the obligation is lodged. The compliance date matters, but the internal review date is what keeps the team calm.
The ATO lodgment program may give registered tax agents different lodgement dates. Firms should avoid hard-coding a single date into every system without checking the client's reporting cycle and the practice's tax agent concessions.
How IAS differs from BAS in workflow
IAS clients may not require the same GST review as BAS clients, but they still require accurate amounts, approvals and payment awareness. Because the work can be smaller, it is easy to delay until the final week. Good workflow software helps prevent small recurring jobs from becoming noisy exceptions.
Recommended reminder and workflow cadence
A strong compliance process separates client communication from internal work allocation. Tax agents can use client reminders at 30, 14, 7, 2 and 0 days before the due date, while managers use earlier workflow dates to check whether records have arrived, preparation has started and review is on track.
This matters because lodgement deadlines are rarely missed for one dramatic reason. They are missed because small items stay hidden: a missing email address, an unassigned manager, a client who has not approved the work, or an obligation sitting in a spreadsheet that only one person trusts. TaxCalendar is built to make those issues visible before they become deadline pressure.
Where TaxCalendar fits
TaxCalendar helps Australian accounting firms turn compliance dates into a visible workflow. Firms can track clients, obligations, due dates, manager ownership, reminder status and lodged status in one place. That gives public practice teams a practical operating layer for BAS, IAS, ATO lodgement calendars, annual returns, client reminders and recurring practice management routines.
Related questions
What is the difference between BAS and IAS?
BAS is generally used for GST and other activity statement obligations. IAS is commonly used for obligations such as PAYG instalments or withholding where a client may not need to report GST.
Are IAS due dates the same for every client?
No. IAS timing depends on the client's reporting cycle and whether the firm lodges through the ATO lodgment program as a registered tax agent.
Can TaxCalendar track IAS separately from BAS?
Yes. Firms can track IAS as a separate obligation type, assign clients, set reminders and monitor status.