The government legislated a one-off 20% reduction of study and training loan balances. The ATO applied it automatically — you didn't need to claim it — and has finished processing it. So the balance you see in myGov already includes the cut.
The order of operations matters, and it's why the change on your statement doesn't look like a clean 20%:
1. The 20% was taken off your balance as at 1 June 2025, before that year's indexation.
2. The 2025 indexation of 3.2% was then recalculated on the reduced balance.
3. Your ordinary compulsory repayments still applied at your 2024-25 assessment.
If your balance was already small, or you made a voluntary payment that took it to zero around that time, the 20% cut can push your loan account into credit. The ATO refunds that credit to you — it doesn't sit on the loan.
Refunds of this kind are processed after the reduction is applied; some took a while to land. If you're seeing a credit balance with no refund yet, it's usually a timing issue in the ATO's processing rather than anything you need to fix.
Separately from the 20% cut, most people with a HECS debt are due money back in their 2026 tax return — because employer withholding didn't switch to the new marginal rates until 24 September 2025, so pays earlier in the year were over-withheld. That's a different refund. Here's how that one works, and you can estimate it here.