One Nation leader Pauline Hanson says Finance Minister Mathias Cormann hasn't tried to change her opposition to the coalition's promised tax cuts.

That comment comes as Labor remains unsure about the tax package, ramping up pressure on the government to clarify how much of the $158 billion plan will go to people earning more than $180,000.

The coalition will need Labor or at least four crossbenchers to support the three-stage tax plan to get it through the Senate when parliament resumes next month.

Labor supports the first stage of the plan, which will mean extra cash for low and middle income-earners.

But it believes the later stage, aimed at flattening the tax rates by mid-2024, shouldn't be legislated years in advance and may benefit too many who are already wealthy.

The coalition has ruled out splitting up the plan, arguing the later stage will bring much-needed structural reform.

Senator Hanson, who directs the two One Nation votes, revealed last week she won't be backing the plan as she believes major infrastructure spending would be a better way to stimulate the economy.

Her opinion remains unchanged after party officials met with treasury bureaucrats on Friday.

She stressed that she hasn't had any senior government figures try to change her mind.

"I haven't been approached by Mathias Cormann. There has been no negotiations that have gone on. I haven't spoken to the prime minister."

Deputy Prime Minister Michael McCormack says that doesn't mean Senator Cormann isn't committed to the plan.

"I'm sure they know each other's numbers," he told reporters in Canberra.

"I know Mathias Cormann is absolutely committed to making sure that we get our full suite of tax measures through the House of Representatives, through the Senate."

The Nationals leader said Labor should respect the mandate for its tax cuts handed to the government by its election victory on May 18.

"Just for once, stop being obstructionist," he said.

Labor leader Anthony Albanese says the opposition has a right to know more about what they are supporting.

"They expect the parliament to go along and just give a rubber stamp," he told reporters in Darwin.

"We're after some facts."

Centre Alliance, which also directs two votes, is also weighing up whether to back the plan.

New analysis of the tax cuts by the Australia Institute also shows they would entrench inequality between what men and women earn.

The progressive public policy think tank says the first part of the tax plan - which is supposed to help taxpayers for the financial year about to end - would almost equally benefit men and women.

But the later stages, which offer the biggest benefits to top earners, would give men $2 worth of tax cuts to every $1 women get.

Asked about the different outcomes, Mr McCormack insisted the government has been boosting participation of women in the workforce.

"Participation of women in the workforce has been one of the real features, one of the crowning achievements of the Liberal National government since we were elected in 2013."