From 1 July 2019, if you have a HECS/HELP debt and you earn above $45,881 you will now start having repayments deducted from your pay, starting at 1%.
Previously you were free of making repayments if your taxable income was below $51,957.
While the study loans are technically interest free, they are indexed to track CPI so your debt will increase if you don't make repayments.
In the past people used to be able to temporarily avoid making repayments by moving overseas, however that is no longer the case.
The government has made this change in response to the ballooning cost of the scheme in recent years.