The Australian Greens are calling on the Labor government to revert to the old planned mining tax to find another $26 billion in revenue in the next four years.
By "plugging the loopholes" in the Mining Resources Revenue Tax (MRRT) and establishing the 40 per cent tax rate recommended by former treasury secretary Ken Henry, the government could be investing in a happier Australia, Australian Greens leader Christine Milne said.
"Ken Henry put forward a well-designed mining super profits tax," Senator Milne said in a statement coinciding with her address to the Greens national conference in Sydney on Saturday.
"Now, instead of confidently investing in a happier, healthier, smarter Australia, (Treasurer) Wayne Swan is scrambling to meet a political surplus target by slugging single parents, cutting support for research, education and training and refusing to lift Newstart to a liveable level."
The government had lost a huge opportunity but it was not too late to change the tax, Senator Milne added.
However, Prime Minister Julia Gillard said she would not be taking advice from anyone about a tax that was already in place.
Ms Gillard said she was confident the government had implemented the mining tax that was right for the nation and she would not be changing it.
"I worked on it directly with (Resources Minister) Martin Ferguson and with Wayne Swan. We agreed on it with some of the nation's biggest mining companies," she told reporters in Sydney on Saturday.
"We have enacted the MRRT we think is appropriate and consequently we won't be taking advice from the Greens political party or anybody else on this question."