Rachel Reeves is facing pressure from Reform UK and the Conservatives to cut spending rather than hike taxes to fill her Budget black hole.
Nigel Farage will set out how he would block European Union citizens in the UK from claiming benefits and slash foreign aid spending, as part of a package to save ÂŁ25 billion this year.
Meanwhile, Tory leader Kemi Badenoch will accuse Ms Reeves of plotting a âstealth tax bombshellâ to fund increased welfare payments because of her failure to cut the benefits bill.
Both the Tory and Reform leaders will set out their plans in speeches in London ahead of Ms Reevesâ November 26 Budget.
Reformâs plans would cut foreign aid to ÂŁ1 billion, which it claimed would save about ÂŁ10 billion.
Ending universal credit payments to foreign nationals would save ÂŁ6 billion this year, the party said.
Other proposals include raising the immigration health surcharge from ÂŁ1,035 a year to ÂŁ2,718, which it claimed would raise ÂŁ5 billion.
The entitlement for EU citizens with settled status to claim benefits is enshrined in the Brexit deal, but Reform said that if Mr Farage was prime minister he would renegotiate that.
Deporting all foreign criminals would save ÂŁ580 million, while previously announced plans from Reform to restrict the personal independence payment would save ÂŁ3.5 billion, the party said.
Reformâs head of policy, Zia Yusuf, told The Times: âLabour has a choice. They can either go ahead and raise taxes on British citizens or they can enact our proposals which put British people first and ask foreign nationals to bear the brunt of the black hole, not British citizens.
âMost British people would consider it outrageous to expect British people to pay higher taxes or see their services cut whilst their money is being spent this way.â
Reform would give EU citizens who are claiming universal credit three months notice as part of a transitional period before ending their payments.
If the EU refused to accept the terms, a Reform UK government would take unilateral action, regardless of the threat of âtrade retaliationâ, The Times reported.
A Labour Party spokesman said: âNigel Farageâs fantasy numbers donât add up, and heâd leave British taxpayers footing a hefty bill.
âFarage is happy to slap British shoppers with higher prices at the checkouts by risking a trade war with Europe.â
Mrs Badenoch will say the U-turn on welfare reforms following a Labour revolt and the expected scrapping of the two-child benefit cap will leave Ms Reeves needing to find ÂŁ8.5 billion.
The Chancellor is thought to be considering extending the freeze on taxation thresholds to help plug the gap in her spending plans and bolster the âheadroomâ she has to avoid breaking her Budget rules.
Freezing the personal tax thresholds means that, as wages rise, more people get dragged into paying tax or shifted into higher bands.
Keeping national insurance and income tax thresholds frozen for two further years until April 2030 would raise around ÂŁ8.3 billion a year by 2029â30, according to the Institute for Fiscal Studies.
Mrs Badenoch will claim Sir Keir Starmer and Ms Reeves are considering âfreezing income tax thresholds so that more and more people are dragged into higher rates through a stealth tax bombshellâ.
Mrs Badenoch will say: âTheyâre hiking taxes on people in work, to give handouts to people on benefits, the last group of people who might still vote Labour.
âItâs not fair, itâs not right, and we will oppose them every single step of the way.â
A Labour spokesman said: âItâs astonishing that the Tories have the barefaced cheek to lecture anyone.
âAfter crashing the economy which sent mortgages rocketing, and leaving a ÂŁ22 billion black hole in the public finances, Kemi Badenoch is still yet to apologise.â
