Opposition Leader Tony Abbott has reiterated his pledge to scrap the mining tax, saying the upcoming federal election will be a referendum on it.
He was giving his response to the media in Sydney following the government's new agreement on the controversial tax.
The headline rate of 40 per cent has been reduced to 30 per cent, despite the federal government's previous refusals to back down on the rate.
Mr Abbott said, "Labor supports a great big new tax on mining - the coalition doesn't. It's as simple as that."
Labor needed a tax because it had turned a $20 billion budget surplus into a $57 billion deficit, Mr Abbott said.
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"The opposition will oppose the new minerals tax," he said. "We will oppose it in opposition and we will rescind it in government."
Mr Abbott also described it as the mining industry getting the best deal from a bad government, saying miners were effectively negotiating with a gun at their heads and the new deal will still hit the industry hard.
Tax changes
Earlier, Prime Minister Julia Gillard announced the compromise, saying it "moves Australia forward" and "moves our mining industry forward".
She said the country "has been stuck on this question for too long".
The tax has been given a new name - the Minerals Resource Rent Tax (MRRT). It was previously known as the Resource Super Profit Tax.
The changes to the tax rate will be limited to iron ore and coal projects, and will only apply to 320 companies.
The government says the reduced rate will make the industry "internationally competitive".
The MRRT will apply to iron ore and coal. However, the current Petroleum Resource Rent Tax will be extended to cover all onshore and offshore oil and gas projects.
There will be no rebate for new exploration costs.
To finance the changes, the company tax rate will now only drop to 29 per cent, instead of the promised 28 per cent.
A policy transition group will be established. The group will be lead by BHP's Don Argus.
The federal government estimates the reforms will reduce revenue by $1.5 billion in the forward estimates.
The announcement follows days of talks between the government and the three big mining companies Rio Tinto, BHP Biliton and Xstrata.
