When will Rachel Reeves realise that by clobbering the wealthy, she hurts working people?

It is a classic PR trick to brief off-the-record that something dire may be about to happen – price rises, redundancies, closures – before an eventual announcement that is not as bad as trailed. Cue sighs of relief.

Something along those lines may be occurring in the Treasury as it plots Rachel Reeves’s next move. Either that, or there is no firm plan and officials are flying kites in the hope one will land well. For weeks now, we have been treated to a steady stream of speculation about the chancellor’s intentions.

We know she is facing a much bigger-than-anticipated hole in the public finances. Labour pledged not to raise taxes on “working people” so income tax, employees’ national insurance and VAT are off limits. That leaves the Treasury few options.

The latest big idea floated is a new national and local property levy to replace stamp duty and council tax – not without merit, since both are outdated. But then came reports that capital gains tax on homes worth more than £1.5m was instead in her crosshairs; currently, primary residences are exempt. What is said to be under discussion is making higher-rate income taxpayers pay 24 per cent on any profit made from the sale of their home if it is worth more than £1.5m, with basic-rate taxpayers facing an 18 per cent bill.

To left-wingers, this may sound like an overdue “mansion tax”. While it may appeal to left-wingers, the levy would rebound. And “mansion” is a misnomer; while it evokes the image of a grand pile, it takes no account of property values in London where many apartments and terraced houses falling into that price bracket are far from mansions.

The point of scrapping stamp duty would be to increase property sales and movement in the housing market. A “mansion tax” would instead freeze it by persuading people to stay put, discouraging downsizing and worsening a housing crisis.

Elderly people would also be hit hard, as a capital gains charge would restrict their ability to sell property to pay for care fees. It is unclear how capital gains would operate alongside inheritance tax. Would some families be facing two separate, hefty bills?

The government has forced itself into a corner; not only did it rule out targeting workers in order to steal Conservative territory, but it won’t cut the soaring welfare bill. With no sign of economic growth, there are few options left except to increase borrowing, which would worsen the deficit. A windfall levy on big firms would send a terrible signal to business that Labour was so desperate to woo in the run-up to the election and would be a nail in the coffin for inward investment.

In reality, Reeves is left with inheritance tax, capital gains and property. Increasingly, it’s simply the better-off who Labour wishes to make worse-off, on the assumption that they can afford it; but many wealthy non-doms have already left. A property levy, coming after VAT on private schools and ending the inheritance tax loophole for farmers, shows a clear direction of travel that could prompt a further exodus of the people who invest and spend, create jobs and donate to charities.

Treasury officials may argue they have remained true to the pledge of leaving working people alone, but many of these homes to be taxed were bought with already-taxed earnings and are lived in by workers.

It is to be hoped that Reeves and her team are engaging in a PR exercise, floating an idea to be quietly dropped. If not, the chancellor risks an expensive political storm.