Fears are mounting that Rachel Reeves will impose one of the biggest tax hikes in history at the Budget.

The respected IFS think-tank has warned that Rachel Reeves needs to find around £25billion of increases on October 30 if she wants to avoid austerity and meet Labour's manifesto commitments. 

However, other analysts have suggested the total could be even higher at £30billion. And Treasury sources have been briefing that the 'black hole' in the books could require £40billion of tax rises and spending cuts. 

But there have been signs of growing anxiety within government over the will be found cash from already-struggling Brits.

With the Treasury now in the 'tunnel' of wrangling with the OBR watchdog, there have been jibes about 'disarray'. 

Rumours have been circulating that manifesto measures such as imposing VAT on private school fees and cracking down on non-doms will not bring in as much as hoped.

And having ruled out changes to headline income tax, VAT and national insurance rates, the Chancellor could be left relying on an array of smaller raids - the effects of which can be very hard to predict.

Here are some of the potential options with estimates for how much they might boost the government's coffers. 

Employer National Insurance - £25bn?

This increasingly looks like being the big ticket revenue-raiser for Ms Reeves.

Currently, employers pay NICs at 13.8 per cent on workers' wages above £9,100 a year. 

But firms do not pay any NICs on money they pay into pensions on behalf of their staff. 

The IFS has previously suggested the rule 'should be reformed', calculating that if employers were charged national insurance on pension contributions at 13.8 per cent it could raise £17billion a year.

Some experts have questioned whether the Chancellor will opt for a reduced rate on employer contributions, rather than the full 13.8 per cent.

There have been warnings the step would hammer pension pots and undermine efforts to shore up poorer workers' savings with auto-enrollment.

Meanwhile, the headline rate of employer NICs could also be targeted. Increasing that by 1p brings in around £8.6billion a year, according to the Treasury's 'ready reckoner'.

Tax thresholds - £7billion

Tax thresholds have been frozen since 2021, and are due to stay so until 2028.

Jeremy Hunt also decided to reduce the top rate mark from £150,000 to £125,000.

The OBR has estimated that the policy will bring 3.8million more people into the tax system through 'fiscal drag' - where incomes rise to account for inflation but tax thresholds stay the same in cash terms. 

Some 2.7million more are expected to pay the higher 40p rate, and 600,000 extra the 45p top rate.

The OBR projected that the government's tax revenues will be boosted by an enormous £41billion a year as a result.

However, there are claims that Ms Reeves is set to extend the freeze again. That would give her an additional £7billion in the final year of the fiscal forecast - when the books have to be balanced.  

VAT on private school fees and non-dom crackdown - £2billion?

The Labour manifesto committed to scrapping non-dom status, adding VAT to private school fees and increasing stamp duty on buyers from abroad. 

The party estimated the VAT move would bring in £1.5billion by 2028, while the other tweaks were projected to bring in billions more together with a vague squeeze on 'tax avoidance'.

However, questions have been raised about the revenue predictions, with warnings that wealthy people will simply leave the country. 

Inheritance tax - £1bn

The Treasury's 'ready reckoner' indicates that increasing the headline IHT rate from 40 per cent to 45 per cent could bring in an extra £1billion.

There is also the possibility of changing the transferrable allowances brought in by George Osborne, although there have been few signs of that happening. 

Pension pots - £2billion 

Think-tanks have floated cutting the amount people can draw out of pensions tax-free from £286,275 to £100,000.

Such a change would raise around £2billion a year. 

However, it would affect about one in five retirees - and crucially cause fury among public sector workers, who typically have the best pensions.

Fuel duty - £1bn 

Ms Reeves is widely expected to clobber more than 30million drivers to help plug the gap, potentially by allowing the 5p fuel duty cut to expire next March.

The reduction was introduced in 2022 by then-Chancellor Rishi Sunak to ease the cost-of-living burden on families amid soaring oil prices.

Prices at the petrol pumps have since fallen, and Ms Reeves could look at restoring the link between duty and inflation for future years.

Reversing the 5p cut and allowing the Escalator to rise with inflation would add about £100 to the annual fuel bill of the average driver.

However, it would bring in relatively little for the Exchequer because the OBR was already assuming that the 5p cut will be axed and duty rises in line with RPI.    

Capital gains tax - £3.5billion?

Tories fear that Ms Reeves will try to conceal revenue-raising from CGT by tinkering with reliefs, as well targeting as the headline rate.

The IFS has suggested that attacking business asset disposal relief (BAD) – a preferential CGT rate for business owners - could bring in £1.5billion. 

So-called 'uplift at death' could also be in the crosshairs. It means that assets such as businesses owned when someone dies are valued for tax purposes from the date when they were acquired, rather than at the date of death.

The asset is, however, inherited at current value. Getting rid of that benefit could bring in £1.6billion.

How much cash could be brought in from pushing up the headline CGT rate is highly uncertain. There are reports that Ms Reeves could opt to up the level on shares but not on other elements such as sales of second homes. 

HMRC estimates that a one percentage point increase in the higher rate of capital gains tax would raise just £100million.

But a 10 percentage point increase or more - as has been mooted in some quarters - could actually cut revenue because so many investors would take action such as delaying sales or quitting the UK.

Pension reliefs - £2.7bn

Reliefs on pension contributions for higher rate taxpayers have long been mooted as a target for Chancellors seeking money.

However, most have avoided the option as it causes major problems for the public sector, could impact pension savings, and would be highly unpopular.

Introducing 30 per cent tax on contributions could bring in £2.7billion according to some estimates. 

Other - £3bn?

Alcohol and tobacco duty, tax-free savings and tweaks to tax thresholds are among the other potential areas where Ms Reeves could look to bring in money.