In 2014 TAXVINE No 43 (21 November 2014), Member 188 wrote about the ATO's practice of appropriating a client's refund and applying it to pay the integrated client account (ICA) before ICA due, and the difficulties getting a refund when the client also pays the same amount on or before the due date.
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."