Mining giant Rio Tinto has not contributed a cent to the federal government's mining tax and does not know when it will start.
However the new chief executive at the world's second largest iron ore miner says Rio was Australia's largest taxpayer the last time a tally was counted in 2011.
The Mineral Resources Rent Tax (MRRT) allows established miners already in production to write off the long term value of their assets from their tax liabilities.
Critics have been scathing of what they call a loophole, with the Australian Greens introducing a bill into parliament to close it.
The MRRT raised just $126 million in its first six months against a full year forecast of $2 billion.
Rio claimed a recognised deferred tax asset of $US1.1 billion in credits to use up before it has to start paying the tax, when announcing its full year result on Thursday.
Chief executive Sam Walsh said he could not predict if it would pay any tax in the current quarter, despite a spike in iron ore prices, due to price and currency unknowns.
"The MRRT was designed as a tax on super profits on the mining industry and importantly the tax is actually operating as it was physically designed," Mr Walsh told a media teleconference from London.
"We are more than paying our way ... our tax payments (in Australia) are about $7 billion a year (including in 2012), we were number one in 2011 and the scorecard is not out for 2012.
"In the reporting period there was an MRRT instalment due on October 22 which coincided with the lowest iron ore prices seen since the GFC ... we don't expect to have an MRRT liability when prices are low."
He said he believed the company still had a positive professional relationship with the federal government, having worked closely with Resources Minister Martin Ferguson and Prime Minister Julia Gillard ahead of this week's decision to keep the Northern Territory's Gove Alumina Refinery open.