How does the IFS suggest Reeves balances the books?

We journalists are not supposed to call the Institute for Fiscal Studies “respected”, because that introduces a value judgement into the fiercely contested world of think tanks, many of whom are competing for the chancellor’s attention before a Budget.

- JOHN RENTOUL

But the IFS tends not to be accused of bias, and its assessments are treated with almost as much reverence as the official - but also independent - Office for Budget Responsibility (OBR).

So the IFS's pre-Budget assessment is indeed treated with respect, and the institute has almost become part of the unwritten constitution that surrounds fiscal events. Most of the media therefore accepts its report, issued today, as definitive. It estimates that Rachel Reeves needs to raise taxes or cut spending by £22bn a year to get back to the position in last year's Budget, when she met her fiscal rules with £10bn a year to spare.

It could be worse, couldn't it?

It is true that £22bn a year is at the lower end of the estimates of how badly the public finances have deteriorated over the past 12 months. But the IFS also says that simply getting back to where the public finances were a year ago is not good enough. It says that Reeves was asking for trouble by cutting it so fine, and that if she leaves such a small margin for error again, she risks having to come back next year or the year after with yet more tax rises or spending cuts.