Hi there,

PAYG amount gets calculated on the gross earning, the pay schedule and employee Tax File declaration. You can still check the ATO's Tax Table for your reference as our payroll system is aligned with the ATO's PAYG Calculation.

If you want to add extra tax to employee's pay run, you can set up a pay run inclusion with a specific start date and end date. Here's how to:

1. Click on the Payroll tab.
2. Click on the employee name you wanted to set up additional tax.
3. Click on Pay Run Inclusions.
4. Click on Add next to Tax Adjustments.
5. Select the applicable Amount (per pay run) option.
6. Enter any notes f you want the employee to see them on their pay slip.
7. Choose the option for When should this pay run inclusion start? And When should this pay run inclusion expire.
8. Click on Save.

That's it! You've now set up a recurring tax adjustment on the employee's pay run.

You can check this link to learn more about setting up Pay run inclusions in QuickBooks Online Payroll. 

Post again in the Community if you have other questions. I'm around to help you.