In 2014 TAXVINE No 32 (4 September 2014), Member 126 wrote about the ATO's practice of appropriating refunds for tax debts not yet due and payable, which causes problems if the taxpayer themselves make a separate, second, payment in relation to the anticipated tax debt.
THE ATO NOW RESPONDS:
"Thank you for your feedback. The Taxation Administration Act 1953 (TAA) allows the Commissioner to apply credits to current or anticipated debts, including debts that are not yet due and payable.
In some circumstances due to timing, the Commissioner may apply a credit against a debt not yet due around the same time that the client makes a payment for that debt. If this does occur, you can request a refund for the client via the Tax Agent Portal or by contacting us on 13 72 86."