The details of the $100-million pay-off between the Greens and the Labor government in exchange for the former's support of the mining tax are no longer secret.

Due to pressure from different groups for the government to be transparent in its dealings, Prime Minister Julia Gillard made more information available a day after the agreement was made public.

The Greens support was in exchange for the government to identify $100 million in savings to make up for the demands of independent MPs that small miners be excluded from the tax.

The savings will come from delaying an earlier promise by the Labor government to phase out the interest withholding tax for foreign banks until 2015-16. The move is expected to yield $130 million savings. The first cut was initially scheduled for 2014-15.

While the Greens may have been pleased with the move, it disappointed the Australian Bankers' Association (ABA).

"If the government was sincere about competition then it would accelerate this tax measure rather than defer it," ABA Chief Executive Officer Steven Munchenberg said in a statement.

The interest withhold tax rate for foreign banks that borrow from their head office was scheduled to go down to 2.5 per cent in 2014-15 from the current 5 per cent and be cut to zero per cent in 2015-16.

"Fiscal circumstances have changed due to global economic events.... We remain committed to implementing this measure from 2014-15," Assistant Treasurer Bill Shorten said in a statement.

"There are big competitive gains to be made from removing interest withholding tax which would benefit Australian consumers," Mr Munchenberg added.

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