Gillard bungled tax deal - Greens

The negotiation skills of the Prime Minister, Julia Gillard, are not all they are cracked up to be, says the leader of the Greens, Christine Milne, as pressure mounts on the government to release details of the mining tax, which is believed to have raised little revenue so far.

''The Prime Minister is always cited as a great negotiator but I have pointed out it's not about whether you get an agreement, it's about whether the agreement you get actually delivers,'' Senator Milne said.

The Greens and the Coalition are calling on the government to reveal how much it is receiving from the Minerals Resource Rent Tax.

The tax on the super profits of coal and iron ore miners was forecast to raise about $2 billion in 2012-13 but industry sources say the big three miners - BHP Billiton, Rio Tinto and Xstrata - don't expect to make any payments this week for the December quarter, repeating the reported outcome in the September quarter.

The Finance Minister, Penny Wong, has said that the government reveals its resource rent tax receipts (which includes the Petroleum Resource Rent Tax) in monthly financial statements but, on advice from the Tax Office, cannot be specific about the mining tax receipts because of taxpayer confidentiality.

This is not a reasonable excuse, Senator Milne said. She wrote to Ms Gillard late last week, reminding her that the Prime Minister had written to the then leader of the Greens, Bob Brown, during negotiations over the mining tax legislation last year, saying monthly updates would be published on revenue collections.

Ms Gillard made renegotiating the mining tax a priority when she became Prime Minister in mid-2010, agreeing that miners could deduct state royalties from their mining tax liability. This meant that when a state raised mining royalties on iron ore or coal, the tax's proceeds were reduced.

''The credibility of those negotiations is coming under increased scrutiny because no money has been raised and the loophole is so great,'' Senator Milne said.

The Greens have been calling on the government to close the mining tax loophole through legislation, a move backed by independent MP Rob Oakeshott. Senator Milne's letter to the Prime Minister reminds her that the Greens have got legislation ready to go.