Nearly three weeks after unveiling the plan to raise nearly $88bn through changes to negative gearing, CGT and trusts, ­Anthony Albanese finally introduced the first tranche of tax ­legislation to parliament and ­declared his new system would cement Labor as the party of aspiration and reform.

But both the Greens and independent senator David Pocock said the high level of ministerial discretion in the Treasurer’s new tax bill was a concern and that it left Dr Chalmers with the ability to fundamentally alter the laws after they are voted on by parliament.

The Australian on Tuesday ­reported that the new legislation contained nine ministerial ­discretions allowing Dr Chalmers to change the rules at any point in the future. The move has ­received wide-ranging criticism from top silks, tax partners and ­accounting experts.

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Greens Treasury spokesman Nick McKim, whose party chaired a parliamentary inquiry into CGT reform, told The Australian on Wednesday that including such powers could determine whether the Greens voted against the bill.

“We aren’t talking about minor tweaks and adjustments here,” Senator McKim said.

“The Treasurer would have the power to fundamentally alter these tax changes after it ­became law.”

“It is a concern to the Greens and it is something we want to explore in the upcoming inquiry.”

Dr Chalmers repeatedly said that the response to the high level of discretionary powers was “a beat-up” and pointed to previous politicians’ use of such powers.

“This is another beat-up, unfortunately,” Dr Chalmers told the Nine Network on Tuesday.

The Albanese government has already moved to minimise scrutiny of its tax bill by allowing just two days of public hearings into its overhaul of the CGT and negative gearing changes, before forcing legislation through the Senate by early July.

With crossbenchers, business leaders and young investors across the country questioning the budget, the Prime Minister in parliament again called critics of his government’s tax plan “allies” of the Liberals, Nationals and One Nation.

“The three right-wing parties and their allies — we saw some of the commentary of the ­allies this morning – want people to earn less, and they oppose ­income-tax cuts,” Mr Albanese said on Wednesday.

“This legislation makes our tax system work better for these 13 million Australians by returning more of the money that they earn.”

Senator Pocock, who sits on the Senate’s powerful committee for the scrutiny of delegated legislation, said he would also push back against the high level of ministerial discretion.

“The Albanese government has gone to extraordinary lengths ­trying to avoid parliamentary scrutiny of these significant reforms to our tax system,” Senator Pocock said.

“I am particularly concerned at the record level of ministerial discretion the Treasurer has sought to award himself in this legislation.

Senator Pocock said that although he had campaigned for and supported changes to the CGT as it related to residential property, he believed there had not been any “meaningful engagement with the community about changes to taxation on other asset classes”.

“This bill as drafted gives the Treasurer the power to issue instruments in the future, without legislation, that would make fundamental changes, such as which asset classes are covered,” he said. 

The Treasurer will be able use legislative instruments to make highly consequential changes to new negative gearing and CGT laws. Among the choices the Treasurer will have are decisions on which assets keep CGT discounts and whether a home counts as a “new build” into the future.

Motions against the Treasurer’s legislative intruments can be made by those who oppose them but such changes don’t carry the same public scrutiny as a change to a bill. Motions against must also be made within a limited number of days.

Dr Chalmers has said other major tax reform throughout history has involved a lot of change.

“If you compare that with other episodes of substantial tax reform it’s not unusual for there to be multiple rounds of legislation or for legislative instruments to be used,” the Treasurer said.

Eight of the discretionary measures relating to taxes on investment cover the definition of a new dwelling, the application of the apportionment method, the additional CGT asset classes for 50 per cent discount, income support payment exemptions from the minimum CGT and a host of other quarantining and other housing definitions.

Legal, tax and accounting professionals blasted Dr Chalmers this week for including the record number of ministerial discretions on what are the most consequential tax changes in decades, criticising the government for including the powers because the rushed changes were not yet properly thought through.

K&L Gates tax partner Stuart Broadfoot said he thought the reason the government “left it to ministers to decide” was because “they’re not ready, and the legislation’s not ready, and they’re trying to ram it through”.

After Labor last year won a large majority by securing 94 of the 150 House of Representatives seats, Mr Broadfoot added: “I assume they have the political space to do it now, and they’re worried that if they wait, then they won’t have the space.”

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