How do I know that HECS/HELP Debt is being deducted?

If you have ticked the box Yes in your TFN form.

When you complete your TFN declaration during onboarding, you are required to make a selection relating to deductions for your HELP/HECS debt. Provided that you have made the correct selection, Oncore will deduct the required level of PAYG tax; taking into account additional amounts for HELP/HECS. The total amount of PAYG tax only is represented on your payslip; but you can check using the ATO's individual tax calculator to see whether you have made the appropriate selections and if they match your payslip.