The Federal Government says privacy considerations prevent it from disclosing how much mining tax has been paid, if any.
It is unclear whether the tax has raised any money in the first six months of its operation.
The Australian newspaper reported yesterday that for the second consecutive quarter BHP Billiton, Rio Tinto and Xstrata will not have to pay the tax.
The Government and big miners are refusing to confirm whether any tax has been paid, although Rio Tinto said it had not spoken to The Australian.
Finance Minister Penny Wong says the Australian Tax Office has advised the Government not to reveal its mining tax earnings if it might breach Commonwealth privacy provisions relating to the release of information about individual taxpayers.
Penny Wong says she already provides financial updates on resource rent taxes, and there are privacy risks with isolating mining tax revenue because it only applies to a small number of companies.
"What we can't do is breach privacy provisions, and the Australian Tax office has advised we're not in a position to provide details of the MRRT if that would breach privacy provisions," she said.
Transparency demands The Opposition and crossbenchers are demanding transparency.
Opposition treasury spokesman Joe Hockey says Ms Wong should be able to provide an answer without breaching the privacy of individual companies.
"She wasn't being asked about individual taxpayers, she was being asked about whether the mining tax was raising a dollar - a single dollar," he told 2GB radio in Sydney.
"Now she has to answer those questions, but she won't." Federal independent MP Rob Oakeshott says if the mining tax is not raising any money now, it never will.
Mr Oakeshott says he would be very surprised if there is not substantial revenue raised from the tax by the May budget, given the current turnaround in iron ore prices.
"They have come back and they are very healthy," he said.
"This MRRT has to be working now and if it's not working now it never will." However, on Twitter, Labor MP and former economics professor Andrew Leigh explained to Mr Oakeshott that even if the miners are making substantial profits, deductions for the cost of building and expanding their mines might be completely offsetting their mining tax bills in the early stages of the tax.
In investment phase, costs are high, so profits may not exceed $75M," Mr Leigh tweeted.