The coalition signed off on formally opposing plans to double the tax rate of super balances above $3 million following a shadow cabinet meeting on Thursday.
The tax rate would increase to 30 per cent in a bid to limit the number of people using their super balances for tax deductions, rather than their retirements.
Deputy Liberal leader Ted O'Brien said the plan to increase the tax rate was unfair.
"Unfortunately, what we have here in Labor's super tax is a series of measures cobbled together, all of which go against what we believe as a party," he told Sky News.
"This is grossly unfair on every single count, and that is why the coalition will be opposing it at every single step."
With the median super balance for 60 to 64 year olds sitting at roughly $200,000 for men and $150,000 for women, the vast majority of Australians are unlikely to feel the impact of Labor's proposal.
It is estimated to affect 0.5 per cent of Australian savers, or roughly 80,000 people according to the Australia Institute.
Prime Minister Anthony Albanese said the proposal had been before federal parliament for some time.
"What we need to do is to make sure that our superannuation system is fair," he told reporters in Melbourne.
"That is what we are setting out to do."
With the coalition ruling itself out of any deal on passing the super tax changes, the government would need to rely on the Greens to pass the laws.
Treasurer Jim Chalmers said the government remains firm on the proposed changes.
"Our intention and our preference would be to legislate what we announced," he told ABC radio on Thursday.
"We've done years of consultation now.
"In this case, with the Greens in the Senate to try and legislate the plan that we announced all of those years ago."
The Greens support the legislation in principle but want the threshold lowered to $2 million and indexed in line with inflation.
Greens senator Sarah Hanson-Young said the ball was in the government's court.
"We want a reform to the system that makes it stronger and fairer," she told Sky News on Thursday.
Critics say the policy's introduction of a tax on unrealised capital gains goes against the fundamentals of the tax system and would have unintended consequences, such as driving investment off-shore and threatening Australia's financial stability.
Unrealised gains are 'paper profits' - increases in the value of assets such as properties or shares that haven't been cashed in.
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