On Thursday, Helge Berger, the IMF’s deputy director for Europe, said the Fund would want to review the details of Reeves’ changes before making a decision.

He said Britain would need a “significant fiscal effort” to stop debt growth overall, but that some borrowing for investment might be appropriate.

Government sources said last week that Reeves would need to raise around £40bn, mostly through higher taxes but also some spending cuts, to balance day-to-day spending with revenues and allow spending on priorities such as health to increase.

If Reeves’ new rule requires the debt to fall by the next election in 2029, it would represent a stricter requirement than current rules based on five-year periods that allow deadlines to be pushed back each year.

Before the election, Reeves had already said he would change one leg of the fiscal rules that allow for a 3 percent budget deficit, including investment spending. He said he would instead aim for a balanced budget that excludes public investments.

The previous government’s plans called for public sector net investment to fall from 2.4 percent to 1.7 percent of GDP over the next five years.

“If we continue on this path we will be adopting a path of decline and that is not a path I want for Britain,” Reeves said.

The Institute for Fiscal Studies think tank estimates that halting this decline would cost around £24bn a year by 2028/29.