Liz Truss's new chancellor Kwasi Kwarteng will deliver an emergency mini-Budget next Friday, The Mirror understands.
Labelled a "fiscal event" by the government, the chancellor is expected to unveil further details of the energy price cap that was announced last week by Ms Truss amid the cost of living crisis.
He is also expected to focus on tax cuts - including reversing April's increase in national insurance - after the new prime minister made taxation a centerpiece of her campaign for the Tory leadership.
There will be no official announcement on the date of the mini-Budget until after Queen Elizabeth II's state funeral on Monday, but sources confirmed it will take place on Friday 23 September.
Last week, Ms Truss announced a £2,500 cap on energy bills for the average household in response to rocketing energy prices, but faced criticism for failing to outline a cost for the intervention.
Mr Kwarteng is expected to set out how the government will fund the package next week, but has already ruled out a windfall tax on the excess profits of oil and gas giants.
On Wednesday No 10 said support for businesses facing devastating energy bills will be made clear next week after being left in the dark since a vague promise to help them last week.
Mr Kwarteng is also expected to deliver on Ms Truss's tax-cutting pledges, including reversing April's national insurance hike - despite warnings it will disproportionately benefit richer households.
The chancellor is set to scrap a planned rise in corporation tax from 19 per cent to 25 per cent in April 2023 in a move that will cost the Treasury billions of pounds.
It comes as Mr Kwarteng came under fire on Thursday after it emerged he is considering scrapping the cap on bankers' bonuses - despite the cost of living crisis.
At the moment bosses are not allowed to award more than twice an employee's salary.
Banking chiefs complain that the cap - introduced as a result of the 2008 financial crash - is driving up salaries, making the UK less attractive than the US or Asia.
But the move has sparked outrage, with the government accused of "boosting bumper bonuses for those as the top" as millions struggle with the harshest wage squeeze in modern history.
Insiders have confirmed to The Mirror that the move - which Boris Johnson shied away from when he was in charge because of backlash fears - is being considered.
The TUC federation of trade unions said Mr Kwarteng should focus on raising everyone's wages rather than "boosting bumper bonuses for those at the top".
Liz Truss's Chancellor has promised a growth-focused shake-up of the economy and told City bosses last week: "We need to be decisive and do things differently."
