The apportionment will embrace the “harsh light of budgetary reality” but “better days are ahead”, Sir Keir Starmer will declare in a talk ahead of Wednesday’s announcement.

The prime minister is expected to alert of “unprecedented” economic challenges but will declare the government will “run towards them” as Labour prepares for its first apportionment in almost 15 years.

The government is expected to announce a series of expected levy hikes, including a rise in the National Insurance (NICs) rate paid by employers which some claim breaks Labour’s manifesto pledge not to boost taxes for “working people”.

The Conservatives have accused Sir Keir of running a government of “broken promises”.

At a talk in the West Midlands on Monday, Sir Keir will debate that the country faces an “unprecedented” test of frail community finances alongside “crumbling community services”.

He will commitment to face what he calls “the tough decisions”.

investing has been growing about the levy rises the chancellor will announce on Wednesday, with Rachel Reeves claiming there is a £22bn “hole” in the community finances left by the Tories.

Sir Keir will declare: “We choose a different path: truthful, responsible, long-term decisions in the interests of working people.”

The Labour event has faced criticism over an expected selection to extend a freeze on income levy thresholds beyond 2028, as well as confusion by what it means by the term “working people”.

The event had promised in its manifesto that it would not boost taxes on working people – explicitly ruling out a rise in VAT, national insurance and income levy.

But ministers have since arrive under pressure to spell out what that actually means.

Speaking to BBC Radio 4’s Today programme, elder minister Pat McFadden said it wasn’t correct to look at “income levels and job descriptions”.

“When we talked about working people we referred to promises that we made in the manifesto around the taxes on wages that people pay – they won’t leave up when the chancellor gets to her feet.”

He added that voters should expect “the most truthful apportionment on Wednesday that you’ve had in many years”.

“We’re going to complete the budgetary falsehood of things being announced which had no money set aside for them.”

• pursue live: Keir Starmer to alert of ‘harsh budgetary reality’ ahead of apportionment
• Analysis: Why this levy-raising apportionment will affect you for years
• When is the apportionment and what might be in it?
• Profile: Who is Rachel Reeves, the UK’s first female chancellor?

Leading economists have warned that it will be workers who eventually pay for the National Insurance rise.

Paul Johnson, the head of the influential Institute for budgetary Studies ponder-tank, told the BBC’s Today programme that when employer National Insurance contributions leave up, often they are “passed through to working people”.

He also suggested that in truth, employees may well be be more affected than self-employed people or tiny business owners by the potential transformation.

“Unless their taxes are raised in the same way that employer national insurance is going to be raised, that’s a very large levy rise that will effectively only impact workers,” he said.

The former financial institution of England governor Lord King of Lothbury also said the debate about not putting taxes up for working people was a “terrible illusion”.

“Ultimately, they fall on the amount that people can spend and you only can raise significant amounts of money by raising taxes on most people, however you worry to define that, but it’s most people will have to pay higher taxes,” he told Sky information.

Critics have argued that employees will also face a greater burden as the chancellor is expected to extend the freeze on income levy thresholds, which is currently due to complete in April 2028 and sees people pulled into paying higher rates through a phenomenon known as “budgetary drag”.

Last week, Reeves signalled that businesses would face an boost in National Insurance, when she said Labour’s election pledge not to boost contributions on “working people” related to the staff element, as opposed to the sum paid by employers.

The government is also reportedly looking at increasing levy on property sales, such as shares and property, as well as changing its own self-imposed rules on how its debts are measured in order to free up money for spending on infrastructure projects.

Speaking to the Sunday with Laura Kuenssberg programme, shadow science secretary Andrew Griffith said Labour had “essentially lied to the British people in terms of their plans”.

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