Chancellor Rachel Reeves took the unusual step this morning of making a speech in Downing Street about November’s Budget, some three weeks before the financial statement is due to be delivered in the House of Commons.

The move follows rising speculation that potential tax rises could be announced in the Budget but the Chancellor refused to give any detail on what will be in her plans, saying only that all will be revealed on 26 November.

She said: “I will make the choices necessary to deliver strong foundations for our economy.”

She stressed that she won’t be making short-term measures, saying that the choices will be, “for this year, and years to come.”

According to the Chancellor: “It will be a Budget led by this government’s values, of fairness and opportunity and focused squarely on the priorities of the British people.”

The Treasury said priorities are to cut hospital waiting lists, cut the national debt and cut the cost of living.

Ms Reeves said: “You will all have heard a lot of speculation about the choices I will make. I understand that – these are important choices that will shape our economy for years to come.

“But it is important that people understand the circumstances we are facing, the principles guiding my choices – and why I believe they will be the right choices for the country.”

Think tank The Resolution Foundation had earlier warned that: “The upcoming Budget is a make-or-break moment for the Government.”

It predicted the Chancellor will need to raise taxes by £21bn-£26bn to cope with lower forecasts for GDP growth.

It said the best option would be, “to raise Income Tax by a 2p rise across all three rates, offset by a 2p cut in employee National Insurance. This would raise £6bn while protecting most workers.

It added: “Other measures are almost certainly going to include some form of extension to the freeze in personal tax thresholds, potentially raising £7.5bn if done for two years.”

Maike Currie, VP of personal finance at PensionBee, said: “By giving us the why well in advance of the what, the Chancellor is paving the way for the difficult choices needed to balance the country’s books - choices that are likely to involve inevitable and painful tax rises.

“If she does opt to raise income tax, rumoured to be up to 2%, she will be the first Chancellor to do so in half a century, breaking Labour’s manifesto commitment not to increase income tax. Such a move will hit everyone - the working population, pensioners and landlords.

“Today’s early morning curveball from the Chancellor, just over 20 days before she opens her red briefcase on November 26, reinforces why this Autumn Budget is both an economic necessity and a political gamble.”