About half a million people who are eligible for the Federal Government's stimulus payment have not received their cash yet because they have not yet lodged a tax return.
Acting Tax Commissioner David Butler said those who had not lodged their 2007-08 tax return must do so by June 30, 2009, otherwise they will forfeit their stimulus payment.
Mr Butler said those using the online E-tax system needed to lodge their return by May 31.
Under the bonus scheme, designed to boost the economy, those with a taxable income of up to $80,000 will receive $900.
Those with an income between $80,001 and $90,000 would receive $600, and those earning between $90,001 and $100,000 would receive $250.
The payments are being made automatically based on details from 2007-08 tax returns.