“The chancellor has confirmed that the costs of the energy price cap will be funded by borrowing, leaving the eye-watering windfall profits of the energy giants untaxed.”

That’s what Labour’s Rachel Reeves told the House of Commons on Friday.

On the same day, the Labour Party’s official Twitter account tweeted: “Under the Tories: households forced to foot the bill. With Labour: a windfall tax on excess oil and gas profits to freeze your energy bills this winter.”

And the shadow chancellor made a similar claim on Radio 4 on Monday, telling listeners that the government is “leaving those excess profits being made by the energy giants on the table”.

She went on to say that “current and future taxpayers are going to have to pay for this, rather than asking those that are making huge profits on the backs of those high prices to make a contribution”.

Hearing and reading these claims, you’d be forgiven for thinking oil and gas companies are not currently subject to a windfall tax. But – and this is the second time in a month we’ve had to FactCheck Labour on this – you’d be wrong.

In fact, Boris Johnson’s government introduced a windfall tax on energy producers in May this year. (A windfall tax is an extra tax on the “excess profits” companies make – in this case, profits over-and-above what they’d have made if the Ukraine war hadn’t pushed up gas prices.)

And the government’s current windfall tax taxes energy producers’ profits at a higher rate, 25 per cent, than Labour had proposed at the time: 10 per cent.

(Though, as we previously reported, Labour’s plan was first announced in January, when we did not yet know how significant the rise in gas prices would be.)

Where the government and Labour disagree is on whether to expand the existing windfall tax to help pay for the government’s energy support.

The opposition wants to back-date the levy to January, and to remove the tax break on companies’ investment spending.

These extensions would bring in an extra £8bn over six months, according to the party’s own estimates.

The independent Institute for Fiscal Studies says that the government’s energy bills plan – which will see the average household bill reach £2,500 rather than over £5,000, as would have happened this winter – could cost £100bn a year.

So even if Labour’s proposals were enacted, they would only cover a fraction of the total bill.

The Labour Party was contacted for comment.