Hi Newtothis02,

Let me guide you on how you can enable monthly IAS in your QuickBooks Online account. Here's how:

1. Click on the GST tab in QBO.
2. Click on Tax Settings.
3. Select Company income tax (PAYG Instalments).
4. Set reporting frequency to Monthly.
5. Click on Save.

When PAYG monthly reporting is enabled, the first two months of each quarter will show you a Prepare IAS button to lodge. After you've lodged the monthly IAS for the first two months, the Prepare BAS option will show for the quarter.

For reference check this link about: Report PAYG Withholding on BAS and IAS. 

Drop by again in the Community if you have further questions about QuickBooks Online. I'm around to help.

So after we Select Company income tax (PAYG Instalments)., and Set reporting frequency to Monthly.

Does QBO will automatically 'link' to the ATO, and once the monthly IAS are submitted in QBO, the submission will "feed" directly to the ATO?

Thanks for getting back to me. Newtothis02.

Let's check your GST center to verify if you have enabled BAS lodgment directly to the ATO. 

1. Click on the GST center.
2. Check if you have a Connect to the ATO button.

If none, this means you have already set up the e-lodgment for your BAS. To be able to confirm it if it enabled or not, I recommend contacting our Customer Care Team. That way, they can ask for your details in a secure form. Or click on the Help icon in QBO and click on Contact Us.

Drop by again in the Community if you have other questions.