Rachel Reeves is said to be considering a tax raid on pensioners amid reports she will reject Labour left calls for a "wealth tax" on Britain's richest.
The Chancellor is set to throw out backbench demands for a blanket levy because those who would be impacted would simply leave the country.
However, a senior Government source has said Reeves would not publicly rule one out, because raising capital gains tax or a tax raid on pensioners could arguably be described as a wealth tax.
Both remain under consideration, the source told The Times.
PA
|Rachel Reeves is expected to cast down calls to impose a two per cent tax on assets worth more than £10million
Ex-Labour chief Lord Kinnock has urged his party to impose a two per cent tax on assets worth more than £10million - a call backed by its more vocal backbenchers.
The senior source added: "The problem is that if the Treasury start shooting down Kinnock's proposal, they end up being boxed in.
"It's not going to happen, but they can't say that publicly."
In a further blow to the Labour left, ministers have branded the idea a "non-starter" and have warned that wealth taxes "just don't work".
One said: "Just look at what's happened in other countries that have introduced them.
TAX RAID FEARS - READ MORE:
PA | Ministers have branded the idea of a wealth tax a 'non-starter'
"They just don't raise money, certainly not the kind of money that we're looking for."
Another cabinet minister said a wealth tax was "off the table", adding: "Wealthy people are mobile, they can move their assets to other more favourable jurisdictions."
Kinnock had claimed that such a tax would raise £11billion towards Reeves's so-called "black hole".
Dan Neidle, a tax lawyer and Labour member, described wealth taxes as "fantasy politics and lazy sloganeering" - and said that they have only raised a "pittance" where they have been implemented.
Around the world, only four countries impose them: Colombia, Norway, Spain and Switzerland.
Eight more have introduced them in the past before scrapping them: Austria, Denmark, Germany, Finland, France, Iceland, Luxembourg and Sweden.
PA | Lord Kinnock (left) had claimed that a wealth tax would raise £11billion towards Labour's so-called 'black hole'
"For a Government that says it prioritises growth, a wealth tax would be a counterintuitive move," Neidle blasted. "People with a brain know it's not going to happen. Anything you do which creates a hostile climate for investment has an impact."
The Chancellor is also poised to extend "stealth taxes" for at least two more years in her Autumn Budget.
Current income tax and National Insurance rates are frozen until 2028 - as a result, more people pay higher rates of tax as their income rises.
Reeves is set to extend the freeze until 2030, which could raise up to £7billion - though critics say it would contradict Labour's manifesto pledge to not hike taxes on "working people".
GB News has approached the Treasury for comment.