The move from shadow treasurer Jim Chalmers marks a shift inside Labor, with MPs now ready to accept stages one and two of the policy, while continuing to debate the third stage of the plan - which by itself is estimated to cost up to $95 billion.

The party could still be left out of negotiations if the Coalition secures the vote of Centre Alliance and One Nation, with talks between the crossbench and Finance Minister Mathias Cormann continuing, in an effort to pass the tax package as soon as possible when Parliament returns in July.

Workers, retailers and the Reserve Bank are depending on the first stage of the package, an offset worth $1080 due to be delivered with tax returns, to offer relief from torpid wage growth and stimulate the economy out of one of its worst results since the global financial crisis.

In his letter to Mr Frydenberg, Dr Chalmers said "Labor stands ready to urgently pass the first tranche of tax cuts to address the weakness in the economy" and requested the total cost to the budget in each year of the tax package.

"We require this additional information to properly consider the latter stages before making final decisions," he said.

According to a Deloitte Access Economics report to be released on Monday, real retail turnover growth is expected to fall to 1.5 per cent this year - its worst result since 2011 - before lifting back up to 2.9 per cent in 2020 if the tax cuts are passed.

Deloitte partner David Rumbens said retailers are taking a "double hit" from tepid wage growth and declining house prices but the immediate injection of a tax offset should produce some stimulus.

"Usually tax cuts result in a marginally higher take home pay packet, supporting a gradual and ongoing increase in consumption," he said.

"The difference this time around is that the tax policy changes will be putting cold hard cash in the hands of consumers once they have lodged their returns."

He said predicted further interest rate cuts would also help lift spending, "as monetary and fiscal stimulus work together for the first time in over a decade".

Futures markets are pricing in the chance of another RBA rate cut in July to a new record low of 1 per cent at more than 70 per cent.

Dr Chalmers has said Labor would avoid the "top end of town" rhetoric that characterised its failed election campaign, but is still seeking information from Mr Frydenberg on the total cost to the budget of tax relief for those earning over $180,000.

The third stage would impose one flat tax rate of 30 cents in the dollar on all earnings between $45,000 and $200,000 if it is implemented in 2024 - delivering larger tax cuts to higher income earners because they pay more tax.

New analysis from the left-leaning Australia Institute found those earning more than $180,000 would get a $33 billion benefit out of the $95 billion total cost over five years from the start date in 2024-25.

In the first year the tax cut comes into effect about $11 billion would go to men and about $6 billion would go to women, the think tank found.

"As the tax cuts progress through the three stages, women get a smaller and smaller share," said Australia Institute senior economist Matt Grudnoff. "This is because the tax cuts increasingly flow to high income earners and men are much more likely to earn higher incomes than women."

Stage two, due to come in from 2022, would see the stage one tax cut of $1080 doubled for most workers and the 32.5 per cent tax bracket increased from $90,000 to $120,000.

Middle income earners get 61 per cent of the benefit of stage two, while high-income taxpayers will get 26 per cent.

The Australia Institute found 47 per cent of the first stage the tax cuts would go to females and 53 per cent to males.