Treasurer Joe Hockey says the deal he did with the Palmer United Party to repeal the mining tax was the best deal that he could do, as workers prepare to see their super shrink.

Incremental increases to the amount employers are required to contribute to the superannuation accounts of their employees will be put on hold for the next seven years after today's deal.

The minerals resource rent tax was supposed to fund the cost to government of increasing the rate to 12 per cent by 2019/20 through annual increases of 0.25 per cent.

Instead, the rate will be frozen when it reaches 10 per cent.

"This is not our preferred option, but it's the only option that has been on the table," Mr Hockey told a press conference.

"If people think that this is going to have a long-term impact on their superannuation, blame Labor. They wouldn't let us keep our election commitments," he said.

Finance Minister Mathias Cormann said they "went for the best possible deal that (they) could achieve in the national interest" which would allow $50b in savings over the next decade.

Finance Minister Mathias Cormann. (AAP) (AAP)

So far the compulsory contribution has risen from 9 per cent to to 9.5 per cent.

Under the deal with PUP, that rate will be frozen until 2021 when it increases to 10 per cent.

After that it will increase by 0.5 per cent annually until it reaches 12 per cent.

For the average worker, the change will mean lost contributions of about $3500 over seven years.

The Minerals Resource Rent Tax Repeal and Other Measures Bill 2014 was passed in the Senate today after the government signed a deal with the Palmer United Party and Senator Ricky Muir.

The bill passed comfortably with 36 votes to 33.

The amendments ensure the low-income superannuation guarantee, income support bonus and the school kids bonus are retained until after the next election.

The school kids bonus will be means tested so that only families earning up to $100,000 will qualify and it will remain until December 31, 2016.

Senator Cormann said the amendments would have a neutral impact on the budget.

PUP senator Glen Lazarus told the Senate the Palmer United Party had “always supported the removal of the mining tax”.

“This is a win for hard-working Australians across the country,” he said.

Opposition senator Penny Wong has slammed the “dirty deal” as another “broken promise” from the government.

She said Prime Minister Tony Abbott promised there would be no deals made with independents and minor parties.

Ms Wong said amendments made to the legislation had only been “dropped” in parliament minutes ahead of Senator Cormann's announcement.

Greens leader Christine Milne said the legislation was being “rammed” through the Senate with no ability for debate on the amendments.

PUP also secured government support to set up two parliamentary committees as part of the negotiations.

The first will explore the possibility of establishing a new Australia Fund to deal with natural disasters, while the other will look at ways of boosting national trade and investment.